When type-checking a component, the declaring NgModule scope is used
to create a directive matcher that contains flattened directive metadata,
i.e. the metadata of a directive and its base classes. This computation
is done for all components, whereas the type-check scope is constant per
NgModule. Additionally, the flattening of metadata is constant per
directive instance so doesn't necessarily have to be recomputed for
each component.
This commit introduces a `TypeCheckScopes` class that is responsible
for flattening directives and computing the scope per NgModule. It
caches the computed results as appropriate to avoid repeated computation.
PR Close#38539
For the compilation of a component, the compiler has to prepare some
information about the directives and pipes that are used in the template.
This information includes an expression for directives/pipes, for usage
within the compilation output. For large NgModule compilation scopes
this has shown to introduce a performance hotspot, as the generation of
expressions is quite expensive. This commit reduces the performance
overhead by only generating expressions for the directives/pipes that
are actually used within the template, significantly cutting down on
the compiler's resolve phase.
PR Close#38539
The type-to-value conversion could previously crash if a symbol was
resolved that does not have any declarations, e.g. because it's imported
from a missing module. This would typically result in a semantic
TypeScript diagnostic and halt further compilation, therefore not
reaching the type-to-value conversion logic. In Bazel however, it turns
out that Angular semantic diagnostics are requested even if there are
semantic TypeScript errors in the program, so it would then reach the
type-to-value conversation and crash.
This commit fixes the unsafe access and adds a test that ignores the
TypeScript semantic error, effectively replicating the situation as
experienced under Bazel.
Fixes#38670
PR Close#38684
Previously, localized strings had very limited or incorrect source-mapping
information available.
Now the i18n AST nodes and related output AST nodes include source-span
information about message-parts and placeholders - including closing tag
placeholders.
This information is then used when generating the final localized string
ASTs to ensure that the correct source-mapping is rendered.
See #38588 (comment)
PR Close#38645
Previously this interface was mostly stored in compiler-cli, but it
contains some properties that would be useful for compiling the
"declare component" prelink code.
This commit moves some of the interface over to the compiler
package so that it can be referenced there without creating a
circular dependency between the compiler and compiler-cli.
PR Close#38594
The `R3TargetBinder` accepts an interface for directive metadata which
declares types for `input` and `output` objects. These types convey the
mapping between the property names for an input or output and the
corresponding property name on the component class. Due to
`R3TargetBinder`'s requirements, this mapping was specified with property
names as keys and field names as values.
However, because of duck typing, this interface was accidentally satisifed
by the opposite mapping, of field names to property names, that was produced
in other parts of the compiler. This form more naturally represents the data
model for inputs.
Rather than accept the field -> property mapping and invert it, this commit
introduces a new abstraction for such mappings which is bidirectional,
eliminating the ambiguous plain object type. This mapping uses new,
unambiguous terminology ("class property name" and "binding property name")
and can be used to satisfy both the needs of the binder as well as those of
the template type-checker (field -> property).
A new test ensures that the input/output metadata produced by the compiler
during analysis is directly compatible with the binder via this unambiguous
new interface.
PR Close#38685
If a type has been renamed when it was exported, we need to
reference the external public alias name rather than the internal
original name for the type. Otherwise we will try to import the
type by its internal name, which is not publicly accessible.
Fixes#38238
PR Close#38666
A recent change to `@angular/localize` brought in the `AbsoluteFsPath` type
from the `@angular/compiler-cli`. But this brought along with it a reference
to NodeJS typings - specifically the `FileSystem` interface refers to the
`Buffer` type from NodeJS.
This affects compilation of `@angular/localize` code that will be run in
the browser - for example projects that reference `loadTranslations()`.
The compilation breaks if the NodeJS typings are not included in the build.
Clearly it is not desirable to have these typings included when the project
is not targeting NodeJS.
This commit replaces references to the NodeJS `Buffer` type with `Uint8Array`,
which is available across all platforms and is actually the super-class of
`Buffer`.
Fixes#38692
PR Close#38700
Previously, the compiler was not able to display template parsing errors as
true `ts.Diagnostic`s that point inside the template. Instead, it would
throw an actual `Error`, and "crash" with a stack trace containing the
template errors.
Not only is this a poor user experience, but it causes the Language Service
to also crash as the user is editing a template (in actuality the LS has to
work around this bug).
With this commit, such parsing errors are converted to true template
diagnostics with appropriate span information to be displayed contextually
along with all other diagnostics. This majorly improves the user experience
and unblocks the Language Service from having to deal with the compiler
"crashing" to report errors.
PR Close#38576
The template type-checking engine includes utilities for creating
`ts.Diagnostic`s for component templates. Previously only the template type-
checker itself created such diagnostics. However, the template parser also
produces errors which should be represented as template diagnostics.
This commit prepares for that conversion by extracting the machinery for
producing template diagnostics into its own sub-package, so that other parts
of the compiler can depend on it without depending on the entire template
type-checker.
PR Close#38576
Previously, the `sourceSpan` and `startSourceSpan` were the same
object, which meant that you had the following situation:
```
element = <div>some content</div>
sourceSpan = <div>
startSourceSpan = <div>
endSourceSpan = </div>
```
This made `sourceSpan` redundant and meant that if you
wanted a span for the whole element including its content
and closing tag, it had to be computed.
Now `sourceSpan` is separated from `startSourceSpan`
resulting in:
```
element = <div>some content</div>
sourceSpan = <div>some content</div>
startSourceSpan = <div>
endSourceSpan = </div>
```
PR Close#38581
Previously the lexer was responsible for deciding whether an "inline"
template should also have its line-endings normalized.
Now this decision is made higher up in the call stack to allow more
flexibility in the parser/lexer.
PR Close#38581
The HTML parser gets an element's namespace either from the tag name
(e.g. `<svg:rect>`) or from its parent element `<svg><rect></svg>`) which
breaks down when an element is inside of an SVG `foreignElement`,
because foreign elements allow nodes from a different namespace to be
inserted into an SVG.
These changes add another flag to the tag definitions which tells child
nodes whether to try to inherit their namespaces from their parents.
It also adds a definition for `foreignObject` with the new flag,
allowing elements placed inside it to infer their namespaces instead.
Fixes#37218.
PR Close#38477
With Typescript 4, `ts.updateIdentifier` is no longer available.
Calling `ts.updateIdentifier` used to return the same node when
`typeArguments` was `undefined` because `node.typeArguments`
was also `undefined`.
Relevant TS code:
```js
function updateIdentifier(node, typeArguments) {
return node.typeArguments !== typeArguments
? updateNode(createIdentifier(ts.idText(node), typeArguments), node)
: node;
}
```
PR Close#38076
Prior to this change, the unary + and - operators would be parsed as `x - 0`
and `0 - x` respectively. The runtime semantics of these expressions are
equivalent, however they may introduce inaccurate template type checking
errors as the literal type is lost, for example:
```ts
@Component({
template: `<button [disabled]="isAdjacent(-1)"></button>`
})
export class Example {
isAdjacent(direction: -1 | 1): boolean { return false; }
}
```
would incorrectly report a type-check error:
> error TS2345: Argument of type 'number' is not assignable to parameter
of type '-1 | 1'.
Additionally, the translated expression for the unary + operator would be
considered as arithmetic expression with an incompatible left-hand side:
> error TS2362: The left-hand side of an arithmetic operation must be of
type 'any', 'number', 'bigint' or an enum type.
To resolve this issues, the implicit transformation should be avoided.
This commit adds a new unary AST node to represent these expressions,
allowing for more accurate type-checking.
Fixes#20845Fixes#36178
PR Close#37918
We had a couple of places where we were assuming that if a particular
symbol has a value, then it will exist at runtime. This is true in most cases,
but it breaks down for `const` enums.
Fixes#38513.
PR Close#38542
This commit adds a `getTemplateOfComponent` method to the
`TemplateTypeChecker` API, which retrieves the actual nodes parsed and used
by the compiler for template type-checking. This is advantageous for the
language service, which may need to query other APIs in
`TemplateTypeChecker` that require the same nodes used to bind the template
while generating the TCB.
Fixes#38352
PR Close#38355
Similarly to the change we landed in the `@angular/core` reflection
capabilities, we need to make sure that ngcc can detect pass-through
delegate constructors for classes using downleveled ES2015 output.
More details can be found in the preceding commit, and in the issue
outlining the problem: #38453.
Fixes#38453.
PR Close#38463
This commit updates the code to move generated i18n statements into the `consts` field of
ComponentDef to avoid invoking `$localize` function before component initialization (to better
support runtime translations) and also avoid problems with lazy-loading when i18n defs may not
be present in a chunk where it's referenced.
Prior to this change the i18n statements were generated at the top leve:
```
var I18N_0;
if (typeof ngI18nClosureMode !== "undefined" && ngI18nClosureMode) {
var MSG_X = goog.getMsg(“…”);
I18N_0 = MSG_X;
} else {
I18N_0 = $localize('...');
}
defineComponent({
// ...
template: function App_Template(rf, ctx) {
i0.ɵɵi18n(2, I18N_0);
}
});
```
This commit updates the logic to generate the following code instead:
```
defineComponent({
// ...
consts: function() {
var I18N_0;
if (typeof ngI18nClosureMode !== "undefined" && ngI18nClosureMode) {
var MSG_X = goog.getMsg(“…”);
I18N_0 = MSG_X;
} else {
I18N_0 = $localize('...');
}
return [
I18N_0
];
},
template: function App_Template(rf, ctx) {
i0.ɵɵi18n(2, 0);
}
});
```
Also note that i18n template instructions now refer to the `consts` array using an index
(similar to other template instructions).
PR Close#38404
For a template that contains for example `<span *ngIf="first"></span>`
there's no need to render the `NgIf` guard expression, as the child
scope does not have any type-checking statements, so any narrowing
effect of the guard is not applicable.
This seems like a minor improvement, however it reduces the number of
flow-node antecedents that TypeScript needs to keep into account for
such cases, resulting in an overall reduction of type-checking time.
PR Close#38418
The template type-checker would always generate a directive declaration
even if its type was never used. For example, directives without any
input nor output bindings nor exportAs references don't need the
directive to be declared, as its type would never be used.
This commit makes the `TcbOp`s that are responsible for declaring a
directive as optional, such that they are only executed when requested
from another operation.
PR Close#38418
The template type-checker would generate a statement with a call
expression for all DOM elements in a template of the form:
```
const _t1 = document.createElement("div");
```
Profiling has shown that this is a particularly expensive call to
perform type inference on, as TypeScript needs to perform signature
selection of `Document.createElement` and resolve the exact type from
the `HTMLElementTagNameMap`. However, it can be observed that the
statement by itself does not contribute anything to the type-checking
result if `_t1` is not actually used anywhere, which is only rarely the
case---it requires that the element is referenced by its name from
somewhere else in the template. Consequently, the type-checker can skip
generating this statement altogether for most DOM elements.
The effect of this optimization is significant in several phases:
1. Less type-check code to generate
2. Less type-check code to emit and parse again
3. No expensive type inference to perform for the call expression
The effect on phase 3 is the most significant here, as type-checking is
not currently incremental in the sense that only phases 1 and 2 can
be reused from a prior compilation. The actual type-checking of all
templates in phase 3 needs to be repeated on each incremental
compilation, so any performance gains we achieve here are very
beneficial.
PR Close#38418
The compiler does not currently report errors when there's an `@Input()`
for a `private`, `protected`, or `readonly` directive/component class member.
This change adds an option to enable reporting errors when a template
attempts to bind to one of these restricted input fields.
PR Close#38249
Prior to this change, the template type checker would always use a
type-constructor to instantiate a directive. This type-constructor call
serves two purposes:
1. Infer any generic types for the directive instance from the inputs
that are passed in.
2. Type check the inputs that are passed into the directive's inputs.
The first purpose is only relevant when the directive actually has any
generic types and using a type-constructor for these cases inhibits
a type-check performance penalty, as a type-constructor's signature is
quite complex and needs to be generated for each directive.
This commit refactors the generated type-check blocks to only generate
a type-constructor call for directives that have generic types. Type
checking of inputs is achieved by generating individual statements for
all inputs, using assignments into the directive's fields.
Even if a type-constructor is used for type-inference of generic types
will the input checking also be achieved using the individual assignment
statements. This is done to support the rework of the language service,
which will start to extract symbol information from the type-check
blocks.
As a future optimization, it may be possible to reduce the number of
inputs passed into a type-constructor to only those inputs that
contribute the the type-inference of the generics. As this is not a
necessity at the moment this is left as follow-up work.
Closes#38185
PR Close#38249
"Quote expressions" are expressions that start with an identifier followed by a
comma, allowing arbitrary syntax to follow. These kinds of expressions would
throw a an error in the template type checker, which would make them hard to
track down. As quote expressions are not generally used at all, the error would
typically occur for URLs that would inadvertently occur in a binding:
```html
<a [href]="https://example.com"></a>
```
This commit lets such bindings be inferred as the `any` type.
Fixes#36568
Resolves FW-2051
PR Close#37917
In TypeScript 3.8 support was added for type-only imports, which only brings in
the symbol as a type, not their value. The Angular compiler did not yet take
the type-only keyword into account when representing symbols in type positions
as value expressions. The class metadata that the compiler emits would include
the value expression for its parameter types, generating actual imports as
necessary. For type-only imports this should not be done, as it introduces an
actual import of the module that was originally just a type-only import.
This commit lets the compiler deal with type-only imports specially, preventing
a value expression from being created.
Fixes#37900
PR Close#37912
When using the safe navigation operator in a binding expression, a temporary
variable may be used for storing the result of a side-effectful call.
For example, the following template uses a pipe and a safe property access:
```html
<app-person-view [enabled]="enabled" [firstName]="(person$ | async)?.name"></app-person-view>
```
The result of the pipe evaluation is stored in a temporary to be able to check
whether it is present. The temporary variable needs to be declared in a separate
statement and this would also cause the full expression itself to be pulled out
into a separate statement. This would compile into the following
pseudo-code instructions:
```js
var temp = null;
var firstName = (temp = pipe('async', ctx.person$)) == null ? null : temp.name;
property('enabled', ctx.enabled)('firstName', firstName);
```
Notice that the pipe evaluation happens before evaluating the `enabled` binding,
such that the runtime's internal binding index would correspond with `enabled`,
not `firstName`. This introduces a problem when the pipe uses `WrappedValue` to
force a change to be detected, as the runtime would then mark the binding slot
corresponding with `enabled` as dirty, instead of `firstName`. This results
in the `enabled` binding to be updated, triggering setters and affecting how
`OnChanges` is called.
In the pseudo-code above, the intermediate `firstName` variable is not strictly
necessary---it only improved readability a bit---and emitting it inline with
the binding itself avoids the out-of-order execution of the pipe:
```js
var temp = null;
property('enabled', ctx.enabled)
('firstName', (temp = pipe('async', ctx.person$)) == null ? null : temp.name);
```
This commit introduces a new `BindingForm` that results in the above code to be
generated and adds compiler and acceptance tests to verify the proper behavior.
Fixes#37194
PR Close#37911
When we were outputting class members for `setClassMetadata` calls,
we were using the string representation of the member name. This can
lead to us generating invalid code when the name contains dashes and
is quoted (e.g. `@Output() 'has-dashes' = new EventEmitter()`), because
the quotes will be stripped for the string representation.
These changes fix the issue by using the original name AST node that was
used for the declaration and which knows whether it's supposed to be
quoted or not.
Fixes#38311.
PR Close#38387
For attribute bindings that target a directive's input, the template
type checker is able to verify that the type of the input expression is
compatible with the directive's declaration for said input. This
checking adheres to the `strictNullChecks` flag as configured in the
TypeScript compilation, such that errors are reported for expressions
that include `undefined` or `null` in their type if the input's
declaration does not include those types.
There was a bug with this level of type-checking for directives that
also declare coercion members, where binding an expression that includes
the `undefined` type to a directive's input that does not include the
`undefined` type would not be reported as error.
This commit fixes the bug by changing the type-constructor in type-check
code to use an intersection type of regular inputs and coerced inputs,
instead of a union type. The union type would inadvertently allow
`undefined` types to be assigned into the regular inputs, as that would
still satisfy the characteristics of a union type.
As a result of this change, you may start to see build failures if
`strictTemplates` is enabled and `strictInputTypes` is not disabled.
These errors are legitimate and some action is required to achieve a
successful build:
1. Update the templates for which an error is reported and introduce the
non-null assertion operator at the end of the expression. This
removes the `undefined` type from the expression's type, making it
appear as a valid assignment.
2. Disable `strictNullInputTypes` in the compiler options. This will
implicitly add the non-null assertion operators similar to option 1,
but all templates in the compilation are affected.
3. Update the directive's input declaration to include the `undefined`
type, if the directive is not implemented in an external library.
PR Close#38273
Roll forward of #38147.
This allows Closure compiler to tree shake unused constructor calls to `NgModuleFactory`, which is otherwise considered
side-effectful. The Angular compiler generates factory objects which are exported but typically not used, as they are
only needed for compatibility with View Engine. This results in top-level constructor calls, such as:
```typescript
export const FooNgFactory = new NgModuleFactory(Foo);
```
`NgModuleFactory` has a side-effecting constructor, so this statement cannot be tree shaken, even if `FooNgFactory` is
never imported. The `NgModuleFactory` continues to reference its associated `NgModule` and prevents the module and all
its unused dependencies from being tree shaken, making Closure builds significantly larger than necessary.
The fix here is to wrap `NgModuleFactory` constructor with `noSideEffects(() => /* ... */)`, which tricks the Closure
compiler into assuming that the invoked function has no side effects. This allows it to tree-shake unused
`NgModuleFactory()` constructors when they aren't imported. Since the factory can be removed, the module can also be
removed (if nothing else references it), thus tree shaking unused dependencies as expected.
The one notable edge case is for lazy loaded modules. Internally, lazy loading is done as a side effect when the lazy
script is evaluated. For Angular, this side effect is registering the `NgModule`. In Ivy this is done by the
`NgModuleFactory` constructor, so lazy loaded modules **cannot** have their top-level `NgModuleFactory` constructor
call tree shaken. We handle this case by looking for the `id` field on `@NgModule` annotations. All lazy loaded modules
include an `id`. When this `id` is found, the `NgModuleFactory` is generated **without** with `noSideEffects()` call,
so Closure will not tree shake it and the module will lazy-load correctly.
PR Close#38320
This introduces a new `ModuleInfo` interface to represent some of the statically analyzed data from an `NgModule`. This
gets passed into transforms to give them more context around a given `NgModule` in the compilation.
PR Close#38320
The `TscPlugin` interface using a type of `ts.CompilerHost&Partial<UnifiedModulesHost>` for the `host` parameter
of the `wrapHost` method. However, prior to this change, the interface implementing `NgTscPlugin` class used a
type of `ts.CompilerHost&UnifiedModulesHost` for the parameter. This change corrects the inconsistency and
allows `UnifiedModulesHost` members to be optional when using the `NgtscPlugin`.
PR Close#38004
Currently the `getInheritedFactory` function is implemented to allow
closure to remove the call if the base factory is unused. However, this
method does not work with terser. By adding the PURE annotation,
terser will also be able to remove the call when unused.
PR Close#38291
This reverts commit 7f8c2225f2.
This commit caused test failures internally, which were traced back to the
optimizer removing NgModuleFactory constructor calls when those calls caused
side-effectful registration of NgModules by their ids.
PR Close#38303
This commit disables one TypeChecker test (added as a part of
https://github.com/angular/angular/pull/38105) which make assertions about the filename while
running on Windows.
Such assertions are currently suffering from a case sensitivity issue.
PR Close#38294
This allows Closure compiler to tree shake unused constructor calls to `NgModuleFactory`, which is otherwise considered
side-effectful. The Angular compiler generates factory objects which are exported but typically not used, as they are
only needed for compatibility with View Engine. This results in top-level constructor calls, such as:
```typescript
export const FooNgFactory = new NgModuleFactory(Foo);
```
`NgModuleFactory` has a side-effecting constructor, so this statement cannot be tree shaken, even if `FooNgFactory` is
never imported. The `NgModuleFactory` continues to reference its associated `NgModule` and prevents the module and all
its unused dependencies from being tree shaken. This effectively prevents all components from being tree shaken, making
Closure builds significantly larger than they should be.
The fix here is to wrap `NgModuleFactory` constructor with `noSideEffects(() => /* ... */)`, which tricks the Closure
compiler into assuming that the invoked function has no side effects. This allows it to tree-shake unused
`NgModuleFactory()` constructors when they aren't imported. Since the factory can be removed, the module can also be
removed (if nothing else references it), thus tree shaking unused components as expected.
PR Close#38147
Large strings constants are now wrapped in a function which is called whenever used. This works around a unique
limitation of Closure, where it will **always** inline string literals at **every** usage, regardless of how large the
string literal is or how many times it is used.The workaround is to use a function rather than a string literal.
Closure has differently inlining semantics for functions, where it will check the length of the function and the number
of times it is used before choosing to inline it. By using a function, `ngtsc` makes Closure more conservative about
inlining large strings, and avoids blowing up the bundle size.This optimization is only used if the constant is a large
string. A wrapping function is not included for other use cases, since it would just increase the bundle size and add
unnecessary runtime performance overhead.
PR Close#38253
This commit adds a method `getDiagnosticsForComponent` to the
`TemplateTypeChecker`, which does the minimum amount of work to retrieve
diagnostics for a single component.
With the normal `ReusedProgramStrategy` this offers virtually no improvement
over the standard `getDiagnosticsForFile` operation, but if the
`TypeCheckingProgramStrategy` supports separate shims for each component,
this operation can yield a faster turnaround for components that are
declared in files with many other components.
PR Close#38105
Previously, a stable template id was implemented for each component in a
file. This commit adds this id to each `TemplateDiagnostic` generated from
the template type-checker, so it can potentially be used for filtration.
PR Close#38105
This commit adds an `overrideComponentTemplate` operation to the template
type-checker. This operation changes the template used during template
type-checking operations.
Overriding a template causes any previous work for it to be discarded, and
the template type-checking engine will regenerate the TCB for that template
on the next request.
This operation can be used by a consumer such as the language service to
get rapid feedback or diagnostics as the user is editing a template file,
without the need for a full incremental build iteration.
Closes#38058
PR Close#38105
Previously, the `TemplateTypeChecker` abstraction allowed fetching
diagnostics for a single file, but under the hood would generate type
checking code for the entire program to satisfy the request.
With this commit, an `OptimizeFor` hint is passed to `getDiagnosticsForFile`
which indicates whether the user intends to request diagnostics for the
whole program or is truly interested in just the single file. If the latter,
the `TemplateTypeChecker` can perform only the work needed to produce
diagnostics for just that file, thus returning answers more efficiently.
PR Close#38105
The template type-checking engine relies on the abstraction interface
`TypeCheckingProgramStrategy` to create updated `ts.Program`s for
template type-checking. The basic API is that the type-checking engine
requests changes to certain files in the program, and the strategy provides
an updated `ts.Program`.
Typically, such changes are made to 'ngtypecheck' shim files, but certain
conditions can cause template type-checking to require "inline" operations,
which change user .ts files instead. The strategy used by 'ngc' (the
`ReusedProgramStrategy`) supports these kinds of updates, but other clients
such as the language service might not always support modifying user files.
To accommodate this, the `TypeCheckingProgramStrategy` interface was
modified to include a `supportsInlineOperations` flag. If an implementation
specifies `false` for inline support, the template type-checking system will
return diagnostics on components which would otherwise require inline
operations.
Closes#38059
PR Close#38105
This commit significantly refactors the 'typecheck' package to introduce a
new abstraction, the `TemplateTypeChecker`. To achieve this:
* a 'typecheck:api' package is introduced, containing common interfaces that
consumers of the template type-checking infrastructure can depend on
without incurring a dependency on the template type-checking machinery as
a whole.
* interfaces for `TemplateTypeChecker` and `TypeCheckContext` are introduced
which contain the abstract operations supported by the implementation
classes `TemplateTypeCheckerImpl` and `TypeCheckContextImpl` respectively.
* the `TemplateTypeChecker` interface supports diagnostics on a whole
program basis to start with, but the implementation is purposefully
designed to support incremental diagnostics at a per-file or per-component
level.
* `TemplateTypeChecker` supports direct access to the type check block of a
component.
* the testing utility is refactored to be a lot more useful, and new tests
are added for the new abstraction.
PR Close#38105
Previously in the template type-checking engine, it was assumed that every
input file would have an associated type-checking shim. The type check block
code for all components in the input file would be generated into this shim.
This is fine for whole-program type checking operations, but to support the
language service's requirements for low latency, it would be ideal to be
able to check a single component in isolation, especially if the component
is declared along with many others in a single file.
This commit removes the assumption that the file/shim mapping is 1:1, and
introduces the concept of component-to-shim mapping. Any
`TypeCheckingProgramStrategy` must provide such a mapping.
To achieve this:
* type checking record information is now split into file-level data as
well as per-shim data.
* components are now assigned a stable `TemplateId` which is unique to the
file in which they're declared.
PR Close#38105
When the `NgIf` directive is used in a template, its context variables
can be used to capture the bound value. This is sometimes used in
complex expressions, where the resulting value is captured in a
context variable. There's two syntax forms available:
1. Binding to `NgIfContext.ngIf` using the `as` syntax:
```html
<span *ngIf="enabled && user as u">{{u.name}}</span>
```
2. Binding to `NgIfContext.$implicit` using the `let` syntax:
```html
<span *ngIf="enabled && user; let u">{{u.name}}</span>
```
Because of the semantics of `ngIf`, it is known that the captured
context variable is truthy, however the template type checker
would not consider them as such and still report errors when
`strict` is enabled.
This commit updates `NgIf`'s context guard to make the types of the
context variables truthy, avoiding the issue.
Based on https://github.com/angular/angular/pull/35125
PR Close#36627
The current implementation of the TypeScriptReflectionHost does not account for members that
are string literals, i.e. `class A { 'string-literal-prop': string; }`
PR Close#38226
Prior to this commit, duplicated styles defined in multiple components in the same file were not
shared between components, thus causing extra payload size. This commit updates compiler logic to
use `ConstantPool` for the styles (while generating the `styles` array on component def), which
enables styles sharing when needed (when duplicates styles are present).
Resolves#38204.
PR Close#38213
This commit splits the transformation into 2 separate steps: Ivy compilation and actual transformation
of corresponding TS nodes. This is needed to have all `o.Expression`s generated before any TS transforms
happen. This allows `ConstantPool` to properly identify expressions that can be shared across multiple
components declared in the same file.
Resolves#38203.
PR Close#38213
This commit updates synthetic host property and listener instruction names to better align with other instructions.
The `ɵɵupdateSyntheticHostBinding` instruction was renamed to `ɵɵsyntheticHostProperty` (to match the `ɵɵhostProperty`
instruction name) and `ɵɵcomponentHostSyntheticListener` was renamed to `ɵɵsyntheticHostListener` since this
instruction is generated for both Components and Directives (so 'component' is removed from the name).
This PR is a followup after PR #35568.
PR Close#37145
Fixes the following issues related to how we validate properties during JIT:
- The invalid property warning was printing `null` as the node name
for `ng-content`. The problem is that when generating a template from
`ng-content` we weren't capturing the node name.
- We weren't running property validation on `ng-container` at all.
This used to be supported on ViewEngine and seems like an oversight.
In the process of making these changes, I found and cleaned up a
few places where we were passing in `LView` unnecessarily.
PR Close#37773
In CLI v10 there was a move to use the new solution-style tsconfig
which became available in TS 3.9.
The result of this is that the standard tsconfig.json no longer contains
important information such as "paths" mappings, which ngcc might need to
correctly compute dependencies.
ngcc (and ngc and tsc) infer the path to tsconfig.json if not given an
explicit tsconfig file-path. But now that means it infers the solution
tsconfig rather than one that contains the useful information it used to
get.
This commit logs a warning in this case to inform the developer
that they might not have meant to load this tsconfig and offer
alternative options.
Fixes#36386
PR Close#38003
The `fs.relative()` method assumed that the file-system is a single tree,
which is not the case in Windows, where you can have multiple drives,
e.g. `C:`, `D:` etc.
This commit changes `fs.relative()` so that it no longer forces the result
to be a `PathSegment` and then flows that refactoring through the rest of
the compiler-cli (and ngcc). The main difference is that now, in some cases,
we needed to check whether the result is "rooted", i.e an `AbsoluteFsPath`,
rather than a `PathSegment`, before using it.
Fixes#36777
PR Close#37959
Builds on top of #34655 to support more cases that could be using a pipe inside host bindings (e.g. ternary expressions or function calls).
Fixes#37610.
PR Close#37883
The `ng_module` rule supports the generation of flat module bundles. In
View Engine, information about this flat module bundle is exposed
as a Bazel provider. This is helpful as other rules like `ng_package`
could rely on this information to determine entry-points for the APF.
With Ivy this currently does not work because the flat module
information is not exposed in the provider. The reason for this is
unclear. We should also provide this information in Ivy so that rules
like `ng_package` can also determine the correct entry-points when a
package is built specifically with `--config=ivy`.
PR Close#36971
The ngtsc testing packages for file_system and logging were missing from the bazel deps rules, which means that they were not included in the releases
PR Close#37977
Currently when the `plural` or `select` keywords in an ICU contain trailing spaces (e.g. `{count, select , ...}`), these spaces are also included into the key names in ICU vars (e.g. "VAR_SELECT "). These trailing spaces are not desirable, since they will later be converted into `_` symbols while normalizing placeholder names, thus causing mismatches at runtime (i.e. placeholder will not be replaced with the correct value). This commit updates the code to trim these spaces while generating an object with placeholders, to make sure the runtime logic can replace these placeholders with the right values.
PR Close#37866
Incremental compilation allows for the output state of one compilation to be
reused as input to the next compilation. This involves retaining references
to instances from prior compilations, which must be done carefully to avoid
memory leaks.
This commit fixes such a leak with a complicated retention chain:
* `TrackedIncrementalBuildStrategy` unnecessarily hangs on to the previous
`IncrementalDriver` (state of the previous compilation) once the current
compilation completes.
In general this is unnecessary, but should be safe as long as the chain
only goes back one level - if the `IncrementalDriver` doesn't retain any
previous `TrackedIncrementalBuildStrategy` instances. However, this does
happen:
* `NgCompiler` indirectly causes retention of previous `NgCompiler`
instances (and thus previous `TrackedIncrementalBuildStrategy` instances)
through accidental capture of the `this` context in a closure created in
its constructor. This closure is wrapped in a `ts.ModuleResolutionCache`
used to create a `ModuleResolver` class, which is passed to the program's
`TraitCompiler` on construction.
* The `IncrementalDriver` retains a reference to the `TraitCompiler` of the
previous compilation, completing the reference chain.
The final retention chain thus looks like:
* `TrackedIncrementalBuildStrategy` of current program
* `.previous`: `IncrementalDriver` of previous program
* `.lastGood.traitCompiler`: `TraitCompiler`
* `.handlers[..].moduleResolver.moduleResolutionCache`: cache
* (via `getCanonicalFileName` closure): `NgCompiler`
* `.incrementalStrategy`: `TrackedIncrementalBuildStrategy` of previous
program.
The closure link is the "real" leak here. `NgCompiler` is creating a closure
for `getCanonicalFileName`, delegating to its
`this.adapter.getCanonicalFileName`, for the purposes of creating a
`ts.ModuleResolutionCache`. The fact that the closure references
`NgCompiler` thus eventually causes previous `NgCompiler` iterations to be
retained. This is also potentially problematic due to the shared nature of
`ts.ModuleResolutionCache`, which is potentially retained across multiple
compilations intentionally.
This commit fixes the first two links in the retention chain: the build
strategy is patched to not retain a `previous` pointer, and the `NgCompiler`
is patched to not create a closure in the first place, but instead pass a
bound function. This ensures that the `NgCompiler` does not retain previous
instances of itself in the first place, even if the build strategy does
end up retaining the previous incremental state unnecessarily.
The third link (`IncrementalDriver` unnecessarily retaining the whole
`TraitCompiler`) is not addressed in this commit as it's a more
architectural problem that will require some refactoring. However, the leak
potential of this retention is eliminated thanks to fixing the first two
issues.
PR Close#37835
When ngcc creates an entry-point program, the `allowJs` option is enabled
in order to operate on the JavaScript source files of the entry-point.
A side-effect of this approach is that external modules that don't ship
declaration files will also have their JavaScript source files loaded
into the program, as the `allowJs` flag allows for them to be imported.
This may pose an issue in certain edge cases, where ngcc would inadvertently
operate on these external modules. This can introduce all sorts of undesirable
behavior and incompatibilities, e.g. the reflection host that is selected for
the entry-point's format could be incompatible with that of the external
module's JavaScript bundles.
To avoid these kinds of issues, module resolution that would resolve to
a JavaScript file located outside of the package will instead be rejected,
as if the file would not exist. This would have been the behavior when
`allowJs` is set to false, which is the case in typical Angular compilations.
Fixes#37508
PR Close#37596
Changes `isWithinPackage` to take an `AbsoluteFsPath` instead of `ts.SourceFile`,
to allow for an upcoming change to use it when no `ts.SourceFile` is available,
but just a path.
PR Close#37596
Previously an error thrown in the `analyzeFn` would cause
the ngcc process to exit immediately without removing the
lockfile, and potentially before the unlocker process had been
successfully spawned resulting in the lockfile being orphaned
and left behind.
Now we catch these errors and remove the lockfile as needed.
PR Close#37739
This commit disables all diagnostic tests for DynamicValue diagnostics which
make assertions about the diagnostic filename while running tests on Windows.
Such assertions are currently suffering from a case sensitivity issue.
PR Close#37763
Several partial_evaluator tests in the diagnostics_spec check assert
correctness of diagnostic filenames. Previously these assertions compared
a resolved (`absoluteFrom`) filename with the TypeScript `ts.SourceFile`'s
`fileName` string, which caused the tests to fail on Windows because the
drive letter case differed.
This commit changes the assertions to use `absoluteFromSourceFile` instead
of the `fileName` string, resulting in an apples-to-apples comparison of
canonicalized paths.
PR Close#37758
This commit introduces a dedicated `DynamicValue` kind to indicate that a value
cannot be evaluated statically as the function body is not just a single return
statement. This allows more accurate reporting of why a function call failed
to be evaluated, i.e. we now include a reference to the function declaration
and have a tailor-made diagnostic message.
PR Close#37587
During AOT compilation, the value of some expressions need to be known at
compile time. The compiler has the ability to statically evaluate expressions
the best it can, but there can be occurrences when an expression cannot be
evaluated statically. For instance, the evaluation could depend on a dynamic
value or syntax is used that the compiler does not understand. Alternatively,
it is possible that an expression could be statically evaluated but the
resulting value would be of an incorrect type.
In these situations, it would be helpful if the compiler could explain why it
is unable to evaluate an expression. To this extend, the static interpreter
in Ivy keeps track of a trail of `DynamicValue`s which follow the path of nodes
that were considered all the way to the node that causes an expression to be
considered dynamic. Up until this commit, this rich trail of information was
not surfaced to a developer so the compiler was of little help to explain
why static evaluation failed, resulting in situations that are hard to debug
and resolve.
This commit adds much more insight to the diagnostic that is produced for static
evaluation errors. For dynamic values, the trail of `DynamicValue` instances
is presented to the user in a meaningful way. If a value is available but not
of the correct type, the type of the resolved value is shown.
Resolves FW-2155
PR Close#37587
Previously, an anonymous type was used for creating a diagnostic with related
information. The anonymous type would then be translated into the necessary
`ts.DiagnosticRelatedInformation` shape within `makeDiagnostic`. This commit
switches the `makeDiagnostic` signature over to taking `ts.DiagnosticRelatedInformation`
directly and introduces `makeRelatedInformation` to easily create such objects.
This is done to aid in making upcoming work more readable.
PR Close#37587
Commit 4213e8d5 introduced shim reference tagging into the compiler, and
changed how the `TypeCheckProgramHost` worked under the hood during the
creation of a template type-checking program. This work enabled a more
incremental flow for template type-checking, but unintentionally introduced
several regressions in performance, caused by poor incrementality during
`ts.Program` creation.
1. The `TypeCheckProgramHost` was made to rely on the `ts.CompilerHost` to
retrieve instances of `ts.SourceFile`s from the original program. If the
host does not return the original instance of such files, but instead
creates new instances, this has two negative effects: it incurs
additional parsing time, and it interferes with TypeScript's ability to
reuse information about such files.
2. During the incremental creation of a `ts.Program`, TypeScript compares
the `referencedFiles` of `ts.SourceFile` instances from the old program
with those in the new program. If these arrays differ, TypeScript cannot
fully reuse the old program. The implementation of reference tagging
introduced in 4213e8d5 restores the original `referencedFiles` array
after a `ts.Program` is created, which means that future incremental
operations involving that program will always fail this comparison,
effectively limiting the incrementality TypeScript can achieve.
Problem 1 exacerbates problem 2: if a new `ts.SourceFile` is created by the
host after shim generation has been disabled, it will have an untagged
`referencedFiles` array even if the original file's `referencedFiles` was
not restored, triggering problem 2 when creating the template type-checking
program.
To fix these issues, `referencedFiles` arrays are now restored on the old
`ts.Program` prior to the creation of a new incremental program. This allows
TypeScript to get the most out of reusing the old program's data.
Additionally, the `TypeCheckProgramHost` now uses the original `ts.Program`
to retrieve original instances of `ts.SourceFile`s where possible,
preventing issues when a host would otherwise return fresh instances.
Together, these fixes ensure that program reuse is as incremental as
possible, and tests have been added to verify this for certain scenarios.
An optimization was further added to prevent the creation of a type-checking
`ts.Program` in the first place if no type-checking is necessary.
PR Close#37641
Previously the `ProgramBasedEntryPointFinder` was parsing all the
entry-points referenced by the program for dependencies even if all the
entry-points had been processed already.
Now this entry-point finder will re-use the `EntryPointManifest` to load
the entry-point dependencies when possible which avoids having to parse
them all again, on every invocation of ngcc.
Previously the `EntryPointManifest` was only used in the
`DirectoryWalkerEntryPointFinder`, which also contained the logic for
computing the contents of the manifest. This logic has been factored out
into an `EntryPointCollector` class. Both the `ProgramBasedEntryPointFinder`
and `DirectoryWalkerEntryPointFinder` now use the `EntryPointManifest` and
the `EntryPointCollector`.
The result of this change is that there is a small cost on the first run of
ngcc to compute and store the manifest - the processing takes 102% of the
processing time before this PR. But on subsequent runs there is a
significant benefit on subsequent runs - the processing takes around 50%
of the processing time before this PR.
PR Close#37665
Source-maps can be linked to from a source-file by a comment at
the end of the file.
Previously the `SourceFileLoader` would read
the first comment that matched `//# sourceMappingURL=` but
this is not valid since some bundlers may include embedded
source-files that contain such a comment.
Now we only look for this comment in the last non-empty line
in the file.
PR Close#32912
Previously localized strings were not mapped to their original
source location, so it was not possible to back-trace them
in tools like the i18n message extractor.
PR Close#32912
Webpack and other build tools sometimes inline the contents of the
source files in their generated source-maps, and at the same time
change the paths to be prefixed with a protocol, such as `webpack://`.
This can confuse tools that need to read these paths, so now it is
possible to provide a mapping to where these files originated.
PR Close#32912
This method will allow us to find the original location given a
generated location, which is useful in fine grained work with
source-mapping. E.g. in `$localize` tooling.
PR Close#32912
The file-writing error in the this commit can also be the result
of the ngcc process dying in the middle of writing files.
This commit improves the error message to offer a resolution
in case this is the reason for the error.
Fixes#36393
PR Close#37672
The `SourceFile` and associated code is general and reusable in
other projects (such as `@angular/localize`). Moving it to `ngtsc`
makes it more easily shared.
PR Close#37114
The `Logger` interface and its related classes are general purpose
and could be used by other tooling. Moving it into ngtsc is a more
suitable place from which to share it - similar to the FileSystem stuff.
PR Close#37114
This dependency host tokenizes files to identify all the imported
paths. This commit calculates the last place in the source code
where there can be an import path; it then exits the tokenization
when we get to this point in the file.
Testing with a reasonably large project showed that the tokenizer
spends about 2/3 as much time scanning files. For example in a
"noop" hot run of ngcc using the program-based entry-point
finder the percentage of time spent in the `scan()` function of
the TS tokenizer goes down from 9.9% to 6.6%.
PR Close#37639
We recently added a transformer to NGC that is responsible for downleveling Angular
decorators and constructor parameter types. The primary goal was to mitigate a
TypeScript limitation/issue that surfaces in Angular projects due to the heavy
reliance on type metadata being captured for DI. Additionally this is a pre-requisite
of making `tsickle` optional in the Angular bazel toolchain.
See: 401ef71ae5 for more context on this.
Another (less important) goal was to make sure that the CLI can re-use
this transformer for its JIT mode compilation. The CLI (as outlined in
the commit mentioned above), already has a transformer for downleveling
constructor parameters. We want to avoid this duplication and exported
the transform through the tooling-private compiler entry-point.
Early experiments in using this transformer over the current one, highlighted
that in JIT, class decorators cannot be downleveled. Angular relies on those
to be invoked immediately for JIT (so that factories etc. are generated upon loading)
The transformer we exposed, always downlevels such class decorators
though, so that would break CLI's JIT mode. We can address the CLI's
needs by adding another flag to skip class decorators. This will allow
us to continue with the goal of de-duplication.
PR Close#37545
Commit 24b2f1da2b introduced an `NgCompiler` which operates on a
`ts.Program` independently of the `NgtscProgram`. The NgCompiler got its
`IncrementalDriver` (for incremental reuse of Angular compilation results)
by looking at a monkey-patched property on the `ts.Program`.
This monkey-patching operation causes problems with the Angular indexer
(specifically, it seems to cause the indexer to retain too much of prior
programs, resulting in OOM issues). To work around this, `IncrementalDriver`
reuse is now handled by a dedicated `IncrementalBuildStrategy`. One
implementation of this interface is used by the `NgtscProgram` to perform
the old-style reuse, relying on the previous instance of `NgtscProgram`
instead of monkey-patching. Only for `NgTscPlugin` is the monkey-patching
strategy used, as the plugin sits behind an interface which only provides
access to the `ts.Program`, not a prior instance of the plugin.
PR Close#37339
Currently the partial evaluator isn't able to resolve a variable declaration that uses destructuring in the form of `const {value} = {value: 0}; const foo = value;`. These changes add some logic to allow for us to resolve the variable's value.
Fixes#36917.
PR Close#37497
Previously, ngcc would only be able to match an ngcc configuration to
packages that were located inside the project's top-level
`node_modules/`. However, if there are multiple versions of a package in
a project (e.g. as a transitive dependency of other packages), multiple
copies of a package (at different versions) may exist in nested
`node_modules/` directories. For example, one at
`<project-root>/node_modules/some-package/` and one at
`<project-root>/node_modules/other-package/node_modules/some-package/`.
In such cases, ngcc was only able to detect the config for the first
copy but not for the second.
This commit fixes this by returning a new instance of
`ProcessedNgccPackageConfig` for each different package path (even if
they refer to the same package name). In these
`ProcessedNgccPackageConfig`, the `entryPoints` paths have been
processed to take the package path into account.
PR Close#37040
This commit adds a `packageName` property to the `EntryPoint` interface.
In a subsequent commit this will be used to retrieve the correct ngcc
configuration for each package, regardless of its path.
PR Close#37040
In order to retrieve the ngcc configuration (if any) for an entry-point,
ngcc has to detect the containing package's version.
Previously, ngcc would try to read the version from the entry-point's
`package.json` file, which was different than the package's top-level
`package.json` for secondary entry-points. For example, it would try to
read it from `node_modules/@angular/common/http/package.json` for
entry-point `@angular/common/http`. However, the `package.json` files
for secondary entry-points are not guaranteed to include a `version`
property.
This commit fixes this by first trying to read the version from the
_package's_ `package.json` (falling back to the entry-point's
`package.json`). For example, it will first try to read it from
`@angular/common/package.json` for entry-point `@angular/common/http`.
PR Close#37040
This commit refactors the way info is retrieved from entry-point
`package.json` files to make it easier to extract more info (such as the
package's name) in the future. It also avoids reading and parsing the
`package.json` file multiple times (as was happening before).
PR Close#37040
Rename the `package` property to `packagePath` on the `EntryPoint`
interface. This makes it more clear that the `packagePath` property
holds the absolute path to the containing package (similar to how `path`
holds the path to the entry-point). This will also align with the
`packageName` property that will be added in a subsequent commit.
This commit also re-orders the `EntryPoint` properties to group related
properties together and to match the order of properties on instances
with that on the interface.
PR Close#37040
Previously, when an entry-point was ignored via an ngcc config, ngcc
would scan sub-directories for sub-entry-points, but would not use the
correct `packagePath`. For example, if `@angular/common` was ignored, it
would look at `@angular/common/http` but incorrectly use
`.../@angular/common/http` as the `packagePath` (instead of
`.../@angular/common`). As a result, it would not retrieve the correct
ngcc config for the actual package.
This commit fixes it by ensuring the correct `packagePath` is used, even
if the primary entry-point corresponding to that path is ignored. In
order to do this, a new return value for `getEntryPointInfo()` is added:
`IGNORED_ENTRY_POINT`. This is used to differentiate between directories
that correspond to no or an incompatible entry-point and those that
correspond to an entry-point that could otherwise be valid but is
explicitly ignored. Consumers of `getEntryPointInfo()` can then use this
info to discard ignored entry-points, but still use the correct
`packagePath` when scanning their sub-directories for secondary
entry-points.
PR Close#37040
Currently Angular internally already handles `InjectionToken` as
predicates for queries. This commit exposes this as public API as
developers already relied on this functionality but currently use
workarounds to satisfy the type constraints (e.g. `as any`).
We intend to make this public as it's low-effort to support, and
it's a significant key part for the use of light-weight tokens as
described in the upcoming guide: https://github.com/angular/angular/pull/36144.
In concrete, applications might use injection tokens over classes
for both optional DI and queries, because otherwise such references
cause classes to be always retained. This was also an issue in View
Engine, but now with Ivy, this pattern became worse, as factories are
directly attached to retained classes (ultimately ending up in the
production bundle, while being unused).
More details in the light-weight token guide and in: https://github.com/angular/angular-cli/issues/16866.
Closes#21152. Related to #36144.
PR Close#37506
Adds @nocollapse to static properties added by ngcc
iff annotateForClosureCompiler is true.
The Closure Compiler will collapse static properties
into the global namespace. Adding this annotation keeps
the properties attached to their respective object, which
allows them to be referenced via a class's constructor.
The annotation is already added by ngtsc and ngc under the
same option, this commit extends the functionality to ngcc.
Closes#36618.
PR Close#36652
It is quite common for the TS compiler to have to add synthetic
types to function signatures, where the developer has not
explicitly provided them. This results in `import(...)` expressions
appearing in typings files. For example in `@ngrx/data` there is a
class with a getter that has an implicit type:
```ts
export declare class EntityCollectionServiceBase<...> {
...
get store() {
return this.dispatcher.store;
}
...
}
```
In the d.ts file for this we get:
```ts
get store(): Store<import("@ngrx/data").EntityCache>;
```
Given that this file is within the `@ngrx/data` package already,
this caused ngcc to believe that there was a circular dependency,
causing it to fail to process the package - and in fact crash!
This commit resolves this problem by ignoring `import()` expressions
when scanning typings programs for dependencies. This ability was
only introduced very recently in a 10.0.0 RC release, and so it has
limited benefit given that up till now ngcc has been able to process
libraries effectively without it. Moreover, in the rare case that a
package does have such a dependency, it should get picked up
by the sync ngcc+CLI integration point.
PR Close#37503
In v7 of Angular we removed `tsickle` from the default `ngc` pipeline.
This had the negative potential of breaking ES2015 output and SSR due
to a limitation in TypeScript.
TypeScript by default preserves type information for decorated constructor
parameters when `emitDecoratorMetadata` is enabled. For example,
consider this snippet below:
```
@Directive()
export class MyDirective {
constructor(button: MyButton) {}
}
export class MyButton {}
```
TypeScript would generate metadata for the `MyDirective` class it has
a decorator applied. This metadata would be needed in JIT mode, or
for libraries that provide `MyDirective` through NPM. The metadata would
look as followed:
```
let MyDirective = class MyDir {}
MyDirective = __decorate([
Directive(),
__metadata("design:paramtypes", [MyButton]),
], MyDirective);
let MyButton = class MyButton {}
```
Notice that TypeScript generated calls to `__decorate` and
`__metadata`. These calls are needed so that the Angular compiler
is able to determine whether `MyDirective` is actually an directive,
and what types are needed for dependency injection.
The limitation surfaces in this concrete example because `MyButton`
is declared after the `__metadata(..)` call, while `__metadata`
actually directly references `MyButton`. This is illegal though because
`MyButton` has not been declared at this point. This is due to the
so-called temporal dead zone in JavaScript. Errors like followed will
be reported at runtime when such file/code evaluates:
```
Uncaught ReferenceError: Cannot access 'MyButton' before initialization
```
As noted, this is a TypeScript limitation because ideally TypeScript
shouldn't evaluate `__metadata`/reference `MyButton` immediately.
Instead, it should defer the reference until `MyButton` is actually
declared. This limitation will not be fixed by the TypeScript team
though because it's a limitation as per current design and they will
only revisit this once the tc39 decorator proposal is finalized
(currently stage-2 at time of writing).
Given this wontfix on the TypeScript side, and our heavy reliance on
this metadata in libraries (and for JIT mode), we intend to fix this
from within the Angular compiler by downleveling decorators to static
properties that don't need to evaluate directly. For example:
```
MyDirective.ctorParameters = () => [MyButton];
```
With this snippet above, `MyButton` is not referenced directly. Only
lazily when the Angular runtime needs it. This mitigates the temporal
dead zone issue caused by a limitation in TypeScript's decorator
metadata output. See: https://github.com/microsoft/TypeScript/issues/27519.
In the past (as noted; before version 7), the Angular compiler by
default used tsickle that already performed this transformation. We
moved the transformation to the CLI for JIT and `ng-packager`, but now
we realize that we can move this all to a single place in the compiler
so that standalone ngc consumers can benefit too, and that we can
disable tsickle in our Bazel `ngc-wrapped` pipeline (that currently
still relies on tsickle to perform this decorator processing).
This transformation also has another positive side-effect of making
Angular application/library code more compatible with server-side
rendering. In principle, TypeScript would also preserve type information
for decorated class members (similar to how it did that for constructor
parameters) at runtime. This becomes an issue when your application
relies on native DOM globals for decorated class member types. e.g.
```
@Input() panelElement: HTMLElement;
```
Your application code would then reference `HTMLElement` directly
whenever the source file is loaded in NodeJS for SSR. `HTMLElement`
does not exist on the server though, so that will become an invalid
reference. One could work around this by providing global mocks for
these DOM symbols, but that doesn't match up with other places where
dependency injection is used for mocking DOM/browser specific symbols.
More context in this issue: #30586. The TL;DR here is that the Angular
compiler does not care about types for these class members, so it won't
ever reference `HTMLElement` at runtime.
Fixes#30106. Fixes#30586. Fixes#30141.
Resolves FW-2196. Resolves FW-2199.
PR Close#37382
Andrew Scott
JoostK
Pete Bacon Darwin
Alex Rickabaugh
crisbeto
Alan Agius
Joey Perrott
Paul Gschwendtner
Andrew Kushnir
Ahn
Andrew Scott
Doug Parker
Charles Lyding
Andrea Canciani
Olivier Combe
Keen Yee Liau
George Kalpakas
David Neil