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Source files that contain directives or components that need an inline type constructor or inline template type-check block would always be considered as affected in incremental rebuilds. The inline operations cause the source file to be updated in the TypeScript program that is created for template type-checking, which becomes the reuse program in a subsequent incremental rebuild. In an incremental rebuild, the source files from the new user program are compared to those from the reuse program. The updated source files are not the same as the original source file from the user program, so the incremental engine would mark the file which needed inline operations as affected. This prevents incremental reuse for these files, causing sub-optimal rebuild performance. This commit attaches the original source file for source files that have been updated with inline operations, such that the incremental engine is able to compare source files using the original source file. Fixes #42543 PR Close #42759
The Program Driver interface
ProgramDriver is a small but important interface which allows the template type-checking machinery to request changes to the current ts.Program, and to receive a new ts.Program with those changes applied. This is used to add template type-checking code to the current ts.Program, eventually allowing for diagnostics to be produced within that code. This operation is abstracted behind this interface because different clients create ts.Programs differently. The Language Service, for example, creates ts.Programs from the current editor state on request, while the TS compiler API creates them explicitly.
When running using the TS APIs, it's important that each new ts.Program be created incrementally from the previous ts.Program. Under a normal compilation, this means that programs alternate between template type checking programs and user programs:
ts.Program#1is created from user input (the user's source files).ts.Program#2is created incrementally on top of #1 for template type-checking, and adds private TCB code.ts.Program#3is created incrementally on top of #2 when the user makes changes to files on disk (incremental build).ts.Program#4is created incrementally on top of #3 to adjust template type-checking code according to the user's changes.
The TsCreateProgramDriver performs this operation for template type-checking ts.Programs built by the command-line compiler or by the CLI. The latest template type-checking program is then exposed via the NgCompiler's getCurrentProgram() operation, and new user programs are expected to be created incrementally on top of the previous template type-checking program.
Programs and the compiler as a service
Not all clients of the compiler follow the incremental tick-tock scenario above. When the compiler is used as a service, new ts.Programs may be generated in response to various queries, either directly to NgCompiler or via the TemplateTypeChecker. Internally, the compiler will use the current ProgramDriver to create these additional ts.Programs as needed.
Incremental builds (new user code changes) may also require changing the ts.Program, using the compiler's incremental ticket process. If the TsCreateProgramDriver is used, the client is responsible for ensuring that any new incremental ts.Programs are created on top of the current program from the previous compilation, which can be obtained via NgCompiler's getCurrentProgram().