Previously these tests were checking multiple specific expression
types. The new helper function is more general and will also support
`PropertyAccessExpression` nodes for `InlineDeclaration` types.
PR Close#38959
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
To improve cross platform support, all file access (and path manipulation)
is now done through a well known interface (`FileSystem`).
For testing a number of `MockFileSystem` implementations are provided.
These provide an in-memory file-system which emulates operating systems
like OS/X, Unix and Windows.
The current file system is always available via the static method,
`FileSystem.getFileSystem()`. This is also used by a number of static
methods on `AbsoluteFsPath` and `PathSegment`, to avoid having to pass
`FileSystem` objects around all the time. The result of this is that one
must be careful to ensure that the file-system has been initialized before
using any of these static methods. To prevent this happening accidentally
the current file system always starts out as an instance of `InvalidFileSystem`,
which will throw an error if any of its methods are called.
You can set the current file-system by calling `FileSystem.setFileSystem()`.
During testing you can call the helper function `initMockFileSystem(os)`
which takes a string name of the OS to emulate, and will also monkey-patch
aspects of the TypeScript library to ensure that TS is also using the
current file-system.
Finally there is the `NgtscCompilerHost` to be used for any TypeScript
compilation, which uses a given file-system.
All tests that interact with the file-system should be tested against each
of the mock file-systems. A series of helpers have been provided to support
such tests:
* `runInEachFileSystem()` - wrap your tests in this helper to run all the
wrapped tests in each of the mock file-systems.
* `addTestFilesToFileSystem()` - use this to add files and their contents
to the mock file system for testing.
* `loadTestFilesFromDisk()` - use this to load a mirror image of files on
disk into the in-memory mock file-system.
* `loadFakeCore()` - use this to load a fake version of `@angular/core`
into the mock file-system.
All ngcc and ngtsc source and tests now use this virtual file-system setup.
PR Close#30921
