When computing i18n messages for templates there are two passes.
This is because messages must be computed before any whitespace
is removed. Then on a second pass, the messages must be recreated
but reusing the message ids from the first pass.
Previously ICUs were losing their legacy ids that had been computed
via the first pass. This commit fixes that by keeping track of the
message from the first pass (`previousMessage`) for ICU placeholder
nodes.
// FW-1637
PR Close#33318
This commit refactors the aliasing system to support multiple different
AliasingHost implementations, which control specific aliasing behavior
in ngtsc (see the README.md).
A new host is introduced, the `PrivateExportAliasingHost`. This solves a
longstanding problem in ngtsc regarding support for "monorepo" style private
libraries. These are libraries which are compiled separately from the main
application, and depended upon through TypeScript path mappings. Such
libraries are frequently not in the Angular Package Format and do not have
entrypoints, but rather make use of deep import style module specifiers.
This can cause issues with ngtsc's ability to import a directive given the
module specifier of its NgModule.
For example, if the application uses a directive `Foo` from such a library
`foo`, the user might write:
```typescript
import {FooModule} from 'foo/module';
```
In this case, foo/module.d.ts is path-mapped into the program. Ordinarily
the compiler would see this as an absolute module specifier, and assume that
the `Foo` directive can be imported from the same specifier. For such non-
APF libraries, this assumption fails. Really `Foo` should be imported from
the file which declares it, but there are two problems with this:
1. The compiler would have to reverse the path mapping in order to determine
a path-mapped path to the file (maybe foo/dir.d.ts).
2. There is no guarantee that the file containing the directive is path-
mapped in the program at all.
The compiler would effectively have to "guess" 'foo/dir' as a module
specifier, which may or may not be accurate depending on how the library and
path mapping are set up.
It's strongly desirable that the compiler not break its current invariant
that the module specifier given by the user for the NgModule is always the
module specifier from which directives/pipes are imported. Thus, for any
given NgModule from a particular module specifier, it must always be
possible to import any directives/pipes from the same specifier, no matter
how it's packaged.
To make this possible, when compiling a file containing an NgModule, ngtsc
will automatically add re-exports for any directives/pipes not yet exported
by the user, with a name of the form: ɵngExportɵModuleNameɵDirectiveName
This has several effects:
1. It guarantees anyone depending on the NgModule will be able to import its
directives/pipes from the same specifier.
2. It maintains a stable name for the exported symbol that is safe to depend
on from code on NPM. Effectively, this private exported name will be a
part of the package's .d.ts API, and cannot be changed in a non-breaking
fashion.
Fixes#29361
FW-1610 #resolve
PR Close#33177
Often the types of an `@Input`'s field don't fully reflect the types of
assignable values. This can happen when an input has a getter/setter pair
where the getter always returns a narrow type, and the setter coerces a
wider value down to the narrow type.
For example, you could imagine an input of the form:
```typescript
@Input() get value(): string {
return this._value;
}
set value(v: {toString(): string}) {
this._value = v.toString();
}
```
Here, the getter always returns a `string`, but the setter accepts any value
that can be `toString()`'d, and coerces it to a string.
Unfortunately TypeScript does not actually support this syntax, and so
Angular users are forced to type their setters as narrowly as the getters,
even though at runtime the coercion works just fine.
To support these kinds of patterns (e.g. as used by Material), this commit
adds a compiler feature called "input coercion". When a binding is made to
the 'value' input of a directive like MatInput, the compiler will look for a
static function with the name ngCoerceInput_value. If such a function is
found, the type-checking expression for the input will be wrapped in a call
to the function, allowing for the expression of a type conversion between
the binding expression and the value being written to the input's field.
To solve the case above, for example, MatInput might write:
```typescript
class MatInput {
// rest of the directive...
static ngCoerceInput_value(value: {toString(): string}): string {
return null!;
}
}
```
FW-1475 #resolve
PR Close#33243
As a hack to get the Ivy compiler ngtsc off the ground, the existing
'allowEmptyCodegenFiles' option was used to control generation of ngfactory
and ngsummary shims during compilation. This option was selected since it's
enabled in google3 but never enabled in external projects.
As ngtsc is now mature and the role shims play in compilation is now better
understood across the ecosystem, this commit introduces two new compiler
options to control shim generation:
* generateNgFactoryShims controls the generation of .ngfactory shims.
* generateNgSummaryShims controls the generation of .ngsummary shims.
The 'allowEmptyCodegenFiles' option is still honored if either of the above
flags are not set explicitly.
PR Close#33256
Currently if a `ModuleWithProviders` is missng its generic type, we throw a cryptic error like:
```
error TS-991010: Value at position 3 in the NgModule.imports of TodosModule is not a reference: [object Object]
```
These changes add a better error to make it easier to debug.
PR Close#33187
Until now, the template type checker has not checked any of the event
bindings that could be present on an element, for example
```
<my-cmp
(changed)="handleChange($event)"
(click)="handleClick($event)"></my-cmp>
```
has two event bindings: the `change` event corresponding with an
`@Output()` on the `my-cmp` component and the `click` DOM event.
This commit adds functionality to the template type checker in order to
type check both kind of event bindings. This means that the correctness
of the bindings expressions, as well as the type of the `$event`
variable will now be taken into account during template type checking.
Resolves FW-1598
PR Close#33125
Prior to this commit, metadata defined on ICU container element was not inherited by the ICU if the whole message is a single ICU (for example: `<ng-container i18n="meaning|description@@id">{count, select, ...}</ng-container>). This commit updates the logic to use parent container i18n meta information for the cases when a message consists of a single ICU.
Fixes#33171
PR Close#33191
Injectable defs are not considered public API, so the property
that contains them should be prefixed with Angular's marker
for "private" ('ɵ') to discourage apps from relying on def
APIs directly.
This commit adds the prefix and shortens the name from
ngInjectableDef to "prov" (for "provider", since injector defs
are known as "inj"). This is because property names cannot
be minified by Uglify without turning on property mangling
(which most apps have turned off) and are thus size-sensitive.
PR Close#33151
Injector defs are not considered public API, so the property
that contains them should be prefixed with Angular's marker
for "private" ('ɵ') to discourage apps from relying on def
APIs directly.
This commit adds the prefix and shortens the name from
ngInjectorDef to inj. This is because property names
cannot be minified by Uglify without turning on property
mangling (which most apps have turned off) and are thus
size-sensitive.
PR Close#33151
The `legacyMessageIdFormat` is taken from the `i18nInFormat` property but we were only considering
`xmb`, `xlf` and `xlf2` values.
The CLI also supports `xliff` and `xliff2` values for the
`i18nInFormat`.
This commit adds support for those aliases.
PR Close#33160
Module defs are not considered public API, so the property
that contains them should be prefixed with Angular's marker
for "private" ('ɵ') to discourage apps from relying on def
APIs directly.
This commit adds the prefix and shortens the name from
ngModuleDef to mod. This is because property names
cannot be minified by Uglify without turning on property
mangling (which most apps have turned off) and are thus
size-sensitive.
PR Close#33142
Pipe defs are not considered public API, so the property
that contains them should be prefixed with Angular's marker
for "private" ('ɵ') to discourage apps from relying on def
APIs directly.
This commit adds the prefix and shortens the name from
ngPipeDef to pipe. This is because property names
cannot be minified by Uglify without turning on property
mangling (which most apps have turned off) and are thus
size-sensitive.
PR Close#33142
Factory defs are not considered public API, so the property
that contains them should be prefixed with Angular's marker
for "private" ('ɵ') to discourage apps from relying on def
APIs directly.
This commit adds the prefix and shortens the name from
ngFactoryDef to fac. This is because property names
cannot be minified by Uglify without turning on property
mangling (which most apps have turned off) and are thus
size-sensitive.
Note that the other "defs" (ngPipeDef, etc) will be
prefixed and shortened in follow-up PRs, in an attempt to
limit how large and conflict-y this change is.
PR Close#33116
Prior to this change, a static attribute that corresponds with a
directive's input would not be type-checked against the type of the
input. This is unfortunate, as a static value always has type `string`,
whereas the directive's input type might be something different. This
typically occurs when a developer forgets to enclose the attribute name
in brackets to make it a property binding.
This commit lets static attributes be considered as bindings with string
values, so that they will be properly type-checked.
PR Close#33066
Prior to this change, the template type checker would always allow a
value of type `undefined` to be passed into a directive's inputs, even
if the input's type did not allow for it. This was due to how the type
constructor for a directive was generated, where a `Partial` mapped
type was used to allow for inputs to be unset. This essentially
introduces the `undefined` type as acceptable type for all inputs.
This commit removes the `Partial` type from the type constructor, which
means that we can no longer omit any properties that were unset.
Instead, any properties that are not set will still be included in the
type constructor call, having their value assigned to `any`.
Before:
```typescript
class NgForOf<T> {
static ngTypeCtor<T>(init: Partial<Pick<NgForOf<T>,
'ngForOf'|'ngForTrackBy'|'ngForTemplate'>>): NgForOf<T>;
}
NgForOf.ngTypeCtor(init: {ngForOf: ['foo', 'bar']});
```
After:
```typescript
class NgForOf<T> {
static ngTypeCtor<T>(init: Pick<NgForOf<T>,
'ngForOf'|'ngForTrackBy'|'ngForTemplate'>): NgForOf<T>;
}
NgForOf.ngTypeCtor(init: {
ngForOf: ['foo', 'bar'],
ngForTrackBy: null as any,
ngForTemplate: null as any,
});
```
This change only affects generated type check code, the generated
runtime code is not affected.
Fixes#32690
Resolves FW-1606
PR Close#33066
Currently, method `getVarDeclarations()` does not try to resolve the type of
exported variable from *ngIf directive. It always returns `any` type.
By resolving the real type of exported variable, it is now possible to use this
type information in language service and provide completions, go to definition
and quick info functionality in expressions that use exported variable.
Also language service will provide more accurate diagnostic errors during
development.
PR Close#33016
Directive defs are not considered public API, so the property
that contains them should be prefixed with Angular's marker
for "private" ('ɵ') to discourage apps from relying on def
APIs directly.
This commit adds the prefix and shortens the name from
ngDirectiveDef to dir. This is because property names
cannot be minified by Uglify without turning on property
mangling (which most apps have turned off) and are thus
size-sensitive.
Note that the other "defs" (ngFactoryDef, etc) will be
prefixed and shortened in follow-up PRs, in an attempt to
limit how large and conflict-y this change is.
PR Close#33110
For elements in a template that look like custom elements, i.e.
containing a dash in their name, the template type checker will now
issue an error with instructions on how the resolve the issue.
Additionally, a property binding to a non-existent property will also
produce a more descriptive error message.
Resolves FW-1597
PR Close#33064
Component defs are not considered public API, so the property
that contains them should be prefixed with Angular's marker
for "private" ('ɵ') to discourage apps from relying on def
APIs directly.
This commit adds the prefix and shortens the name from
`ngComponentDef` to `cmp`. This is because property names
cannot be minified by Uglify without turning on property
mangling (which most apps have turned off) and are thus
size-sensitive.
Note that the other "defs" (ngDirectiveDef, etc) will be
prefixed and shortened in follow-up PRs, in an attempt to
limit how large and conflict-y this change is.
PR Close#33088
For v9 we want the migration to the new i18n to be as
simple as possible.
Previously the developer had to positively choose to use
legacy messsage id support in the case that their translation
files had not been migrated to the new format by setting the
`legacyMessageIdFormat` option in tsconfig.json to the format
of their translation files.
Now this setting has been changed to `enableI18nLegacyMessageFormat`
as is a boolean that defaults to `true`. The format is then read from
the `i18nInFormat` option, which was previously used to trigger translations
in the pre-ivy angular compiler.
PR Close#33053
Currently Ivy stores the element attributes into an array above the component def and passes it into the relevant instructions, however the problem is that upon minification the array will get a unique name which won't compress very well. These changes move the attributes array into the component def and pass in the index into the instructions instead.
Before:
```
const _c0 = ['foo', 'bar'];
SomeComp.ngComponentDef = defineComponent({
template: function() {
element(0, 'div', _c0);
}
});
```
After:
```
SomeComp.ngComponentDef = defineComponent({
consts: [['foo', 'bar']],
template: function() {
element(0, 'div', 0);
}
});
```
A couple of cases that this PR doesn't handle:
* Template references are still in a separate array.
* i18n attributes are still in a separate array.
PR Close#32798
The `$localize` library uses a new message digest function for
computing message ids. This means that translations in legacy
translation files will no longer match the message ids in the code
and so will not be translated.
This commit adds the ability to specify the format of your legacy
translation files, so that the appropriate message id can be rendered
in the `$localize` tagged strings. This results in larger code size
and requires that all translations are in the legacy format.
Going forward the developer should migrate their translation files
to use the new message id format.
PR Close#32937
In an attempt to be compatible with previous translation files
the Angular compiler was generating instructions that always
included the message id. This was because it was not possible
to accurately re-generate the id from the calls to `$localize()` alone.
In line with https://hackmd.io/EQF4_-atSXK4XWg8eAha2g this
commit changes the compiler so that it only renders ids if they are
"custom" ones provided by the template author.
NOTE:
When translating messages generated by the Angular compiler
from i18n tags in templates, the `$localize.translate()` function
will compute message ids, if no custom id is provided, using a
common digest function that only relies upon the information
available in the `$localize()` calls.
This computed message id will not be the same as the message
ids stored in legacy translation files. Such files will need to be
migrated to use the new common digest function.
This only affects developers who have been trialling `$localize`, have
been calling `loadTranslations()`, and are not exclusively using custom
ids in their templates.
PR Close#32867
Metadata blocks are delimited by colons. Previously the code naively just
looked for the next colon in the string as the end marker.
This commit supports escaping colons within the metadata content.
The Angular compiler has been updated to add escaping as required.
PR Close#32867
With #31953 we moved the factories for components, directives and pipes into a new field called `ngFactoryDef`, however I decided not to do it for injectables, because they needed some extra logic. These changes set up the `ngFactoryDef` for injectables as well.
For reference, the extra logic mentioned above is that for injectables we have two code paths:
1. For injectables that don't configure how they should be instantiated, we create a `factory` that proxies to `ngFactoryDef`:
```
// Source
@Injectable()
class Service {}
// Output
class Service {
static ngInjectableDef = defineInjectable({
factory: () => Service.ngFactoryFn(),
});
static ngFactoryFn: (t) => new (t || Service)();
}
```
2. For injectables that do configure how they're created, we keep the `ngFactoryDef` and generate the factory based on the metadata:
```
// Source
@Injectable({
useValue: DEFAULT_IMPL,
})
class Service {}
// Output
export class Service {
static ngInjectableDef = defineInjectable({
factory: () => DEFAULT_IMPL,
});
static ngFactoryFn: (t) => new (t || Service)();
}
```
PR Close#32433
Prior to this commit, the `ngProjectAs` attribute was only included with a special flag and in a parsed format. As a result, projected node was missing `ngProjectAs` attribute as well as other attributes added after `ngProjectAs` one. This is problematic since app code might rely on the presence of `ngProjectAs` attribute (for example in CSS). This commit fixes the problem by including `ngProjectAs` into attributes array as a regular attribute and also makes sure that the parsed version of the `ngProjectAs` attribute with a special marker is added after regular attributes (thus we set them correctly at runtime). This change also aligns View Engine and Ivy behavior.
PR Close#32784
Now that the `$localize` translations are `MessageId` based the
compiler must render `MessageId`s in its generated `$localize` code.
This is because the `MessageId` used by the compiler is computed
from information that does not get passed through to the `$localize`
tagged string.
For example, the generated code for the following template
```html
<div id="static" i18n-title="m|d" title="introduction"></div>
```
will contain these localization statements
```ts
if (ngI18nClosureMode) {
/**
* @desc d
* @meaning m
*/
const MSG_EXTERNAL_8809028065680254561$$APP_SPEC_TS_1 = goog.getMsg("introduction");
I18N_1 = MSG_EXTERNAL_8809028065680254561$$APP_SPEC_TS_1;
}
else {
I18N_1 = $localize \`:m|d@@8809028065680254561:introduction\`;
}
```
Since `$localize` is not able to accurately regenerate the source-message
(and so the `MessageId`) from the generated code, it must rely upon the
`MessageId` being provided explicitly in the generated code.
The compiler now prepends all localized messages with a "metadata block"
containing the id (and the meaning and description if defined).
Note that this metadata block will also allow translation file extraction
from the compiled code - rather than relying on the legacy ViewEngine
extraction code. (This will be implemented post-v9).
Although these metadata blocks add to the initial code size, compile-time
inlining will completely remove these strings and so will not impact on
production bundle size.
PR Close#32594
This patch is a final major refactor in styling Angular.
This PR includes three main fixes:
All temporary state taht is persisted between template style/class application
and style/class application in host bindings is now removed.
Removes the styling() and stylingApply() instructions.
Introduces a "direct apply" mode that is used apply prop-based
style/class in the event that there are no map-based bindings as
well as property collisions.
PR Close#32259
PR Close#32591
If an <ng-template> contains a structural directive (for example *ngIf), Ngtsc generates extra template function with 1 template instruction call. When <ng-template> tag also contains i18n attribute on it, we generate i18nStart and i18nEnd instructions around it, which is unnecessary and breaking runtime. This commit adds a logic to make sure we do not generate i18n instructions in case only `template` is present.
PR Close#32623
This patch is a final major refactor in styling Angular.
This PR includes three main fixes:
All temporary state taht is persisted between template style/class application
and style/class application in host bindings is now removed.
Removes the styling() and stylingApply() instructions.
Introduces a "direct apply" mode that is used apply prop-based
style/class in the event that there are no map-based bindings as
well as property collisions.
PR Close#32259
PR Close#32596
This patch is a final major refactor in styling Angular.
This PR includes three main fixes:
All temporary state taht is persisted between template style/class application
and style/class application in host bindings is now removed.
Removes the styling() and stylingApply() instructions.
Introduces a "direct apply" mode that is used apply prop-based
style/class in the event that there are no map-based bindings as
well as property collisions.
PR Close#32259
Replaces the `select` instruction with a new one called `advance`. Instead of the jumping to a specific index, the new instruction goes forward X amount of elements. The advantage of doing this is that it should generate code the compresses better.
PR Close#32516
The `goog.getMsg()` function requires placeholder names to be camelCased.
This is not the case for `$localize`. Here placeholder names need
match what is serialized to translation files.
Specifically such placeholder names keep their casing but have all characters
that are not in `a-z`, `A-Z`, `0-9` and `_` converted to `_`.
PR Close#32509
Prior to this change, the template source mapping details were always
built during the analysis phase, under the assumption that pre-analysed
templates would always correspond with external templates. This has
turned out to be a false assumption, as inline templates are also
pre-analyzed to be able to preload any stylesheets included in the
template.
This commit fixes the bug by capturing the template source mapping
details at the moment the template is parsed, which is either during the
preanalysis phase when preloading is available, or during the analysis
phase when preloading is not supported.
Tests have been added to exercise the template error mapping in
asynchronous compilations where preloading is enabled, similar to how
the CLI performs compilations.
Fixes#32538
PR Close#32544
Prior to this commit, complex expressions (that require additional statements to be generated) were handled incorrectly in case they were used in attributes annotated with i18n flags. The problem was caused by the fact that extra statements were not appended to the temporary vars block, so they were missing in generated code. This commit updated the logic to use the `convertPropertyBinding`, which contains the necessary code to append extra statements. The `convertExpressionBinding` function was removed as it duplicates the `convertPropertyBinding` one (for the most part) and is no longer used.
PR Close#32309
Previously the template compiler would generate the same jsdoc comment
block for `$localize` as for `goog.getMsg()`. But it turns out that
the closure compiler will complain if the `@desc` and `@meaning`
tags are used for non-`getMsg()` calls.
For now we do not generate the comments for `$localize` calls. They are
not being used at the moment.
In the future it would be good to be able to extract the descriptions and
meanings from the `$localize` calls rather than relying upon the `getMsg()`
calls, which we do now. So we need to find a workaround for this constraint.
PR Close#32473
This commit changes the Angular compiler (ivy-only) to generate `$localize`
tagged strings for component templates that use `i18n` attributes.
BREAKING CHANGE
Since `$localize` is a global function, it must be included in any applications
that use i18n. This is achieved by importing the `@angular/localize` package
into an appropriate bundle, where it will be executed before the renderer
needs to call `$localize`. For CLI based projects, this is best done in
the `polyfills.ts` file.
```ts
import '@angular/localize';
```
For non-CLI applications this could be added as a script to the index.html
file or another suitable script file.
PR Close#31609
Reworks the compiler to output the factories for directives, components and pipes under a new static field called `ngFactoryFn`, instead of the usual `factory` property in their respective defs. This should eventually allow us to inject any kind of decorated class (e.g. a pipe).
**Note:** these changes are the first part of the refactor and they don't include injectables. I decided to leave injectables for a follow-up PR, because there's some more cases we need to handle when it comes to their factories. Furthermore, directives, components and pipes make up most of the compiler output tests that need to be refactored and it'll make follow-up PRs easier to review if the tests are cleaned up now.
This is part of the larger refactor for FW-1468.
PR Close#31953
In ngc is was valid to set the "flatModuleOutFile" option to "null". This is sometimes
necessary if a tsconfig extends from another one but the "fatModuleOutFile" option
needs to be unset (note that "undefined" does not exist as value in JSON)
Now if ngtsc is used to compile the project, ngtsc will fail with an error because it
tries to do string manipulation on the "flatModuleOutFile". This happens because
ngtsc only skips flat module indices if the option is set to "undefined".
Since this is not compatible with what was supported in ngc and such exceptions
should be avoided, the flat module check is now aligned with ngc.
```
TypeError: Cannot read property 'replace' of null
at Object.normalizeSeparators (/home/circleci/project/node_modules/@angular/compiler-cli/src/ngtsc/util/src/path.js:35:21)
at new NgtscProgram (/home/circleci/project/node_modules/@angular/compiler-cli/src/ngtsc/program.js:126:52)
```
Additionally setting the `flatModuleOutFile` option to an empty string
currently results in unexpected behavior. No errors is thrown, but the
flat module index file will be `.ts` (no file name; just extension).
This is now also fixed by treating an empty string similarly to
`null`.
PR Close#32235
Previously, ngtsc attempted to use the .d.ts schema for HTML elements to
check bindings to DOM properties. However, the TypeScript lib.dom.d.ts
schema does not perfectly align with the Angular DomElementSchemaRegistry,
and these inconsistencies would cause issues in apps. There is also the
concern of supporting both CUSTOM_ELEMENTS_SCHEMA and NO_ERRORS_SCHEMA which
would have been very difficult to do in the existing system.
With this commit, the DomElementSchemaRegistry is employed in ngtsc to check
bindings to the DOM. Previous work on producing template diagnostics is used
to support generation of this different kind of error with the same high
quality of error message.
PR Close#32171
Historically, the Angular Compiler has produced both native TypeScript
diagnostics (called ts.Diagnostics) and its own internal Diagnostic format
(called an api.Diagnostic). This was done because TypeScript ts.Diagnostics
cannot be produced for files not in the ts.Program, and template type-
checking diagnostics are naturally produced for external .html template
files.
This design isn't optimal for several reasons:
1) Downstream tooling (such as the CLI) must support multiple formats of
diagnostics, adding to the maintenance burden.
2) ts.Diagnostics have gotten a lot better in recent releases, with support
for suggested changes, highlighting of the code in question, etc. None of
these changes have been of any benefit for api.Diagnostics, which have
continued to be reported in a very primitive fashion.
3) A future plugin model will not support anything but ts.Diagnostics, so
generating api.Diagnostics is a blocker for ngtsc-as-a-plugin.
4) The split complicates both the typings and the testing of ngtsc.
To fix this issue, this commit changes template type-checking to produce
ts.Diagnostics instead. Instead of reporting a special kind of diagnostic
for external template files, errors in a template are always reported in
a ts.Diagnostic that highlights the portion of the template which contains
the error. When this template text is distinct from the source .ts file
(for example, when the template is parsed from an external resource file),
additional contextual information links the error back to the originating
component.
A template error can thus be reported in 3 separate ways, depending on how
the template was configured:
1) For inline template strings which can be directly mapped to offsets in
the TS code, ts.Diagnostics point to real ranges in the source.
This is the case if an inline template is used with a string literal or a
"no-substitution" string. For example:
```typescript
@Component({..., template: `
<p>Bar: {{baz}}</p>
`})
export class TestCmp {
bar: string;
}
```
The above template contains an error (no 'baz' property of `TestCmp`). The
error produced by TS will look like:
```
<p>Bar: {{baz}}</p>
~~~
test.ts:2:11 - error TS2339: Property 'baz' does not exist on type 'TestCmp'. Did you mean 'bar'?
```
2) For template strings which cannot be directly mapped to offsets in the
TS code, a logical offset into the template string will be included in
the error message. For example:
```typescript
const SOME_TEMPLATE = '<p>Bar: {{baz}}</p>';
@Component({..., template: SOME_TEMPLATE})
export class TestCmp {
bar: string;
}
```
Because the template is a reference to another variable and is not an
inline string constant, the compiler will not be able to use "absolute"
positions when parsing the template. As a result, errors will report logical
offsets into the template string:
```
<p>Bar: {{baz}}</p>
~~~
test.ts (TestCmp template):2:15 - error TS2339: Property 'baz' does not exist on type 'TestCmp'.
test.ts:3:28
@Component({..., template: TEMPLATE})
~~~~~~~~
Error occurs in the template of component TestCmp.
```
This error message uses logical offsets into the template string, and also
gives a reference to the `TEMPLATE` expression from which the template was
parsed. This helps in locating the component which contains the error.
3) For external templates (templateUrl), the error message is delivered
within the HTML template file (testcmp.html) instead, and additional
information contextualizes the error on the templateUrl expression from
which the template file was determined:
```
<p>Bar: {{baz}}</p>
~~~
testcmp.html:2:15 - error TS2339: Property 'baz' does not exist on type 'TestCmp'.
test.ts:10:31
@Component({..., templateUrl: './testcmp.html'})
~~~~~~~~~~~~~~~~
Error occurs in the template of component TestCmp.
```
PR Close#31952
Pete Bacon Darwin
Alex Rickabaugh
Matias Niemelä
crisbeto
JoostK
Igor Minar
Andrew Kushnir
Kara Erickson
Andrius
Paul Gschwendtner