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@sriraamas sriraamas commented Jul 29, 2016

Please check if the PR fulfills these requirements

What kind of change does this PR introduce? (check one with "x")

[x ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Other... Please describe:

What is the current behavior? (You can also link to an open issue here)

What is the new behavior?

Does this PR introduce a breaking change? (check one with "x")

[ ] Yes
[x ] No

If this PR contains a breaking change, please describe the impact and migration path for existing applications: ...

Other information:

@lewistg lewistg merged this pull request into lucidsoftware:closure-bundle Jul 29, 2016
DavidANeil pushed a commit that referenced this pull request May 22, 2020
…ular#36211)

This optimization builds on a lot of prior work to finally make type-
checking of templates incremental.

Incrementality requires two main components:
- the ability to reuse work from a prior compilation.
- the ability to know when changes in the current program invalidate that
  prior work.

Prior to this commit, on every type-checking pass the compiler would
generate new .ngtypecheck files for each original input file in the program.

1. (Build #1 main program): empty .ngtypecheck files generated for each
   original input file.

2. (Build #1 type-check program): .ngtypecheck contents overridden for those
   which have corresponding components that need type-checked.

3. (Build #2 main program): throw away old .ngtypecheck files and generate
   new empty ones.

4. (Build #2 type-check program): same as step 2.

With this commit, the `IncrementalDriver` now tracks template type-checking
_metadata_ for each input file. The metadata contains information about
source mappings for generated type-checking code, as well as some
diagnostics which were discovered at type-check analysis time. The actual
type-checking code is stored in the TypeScript AST for type-checking files,
which is now re-used between programs as follows:

1. (Build #1 main program): empty .ngtypecheck files generated for each
   original input file.

2. (Build #1 type-check program): .ngtypecheck contents overridden for those
   which have corresponding components that need type-checked, and the
   metadata registered in the `IncrementalDriver`.

3. (Build #2 main program): The `TypeCheckShimGenerator` now reuses _all_
   .ngtypecheck `ts.SourceFile` shims from build #1's type-check program in
   the construction of build #2's main program. Some of the contents of
   these files might be stale (if a component's template changed, for
   example), but wholesale reuse here prevents unnecessary changes in the
   contents of the program at this point and makes TypeScript's job a lot
   easier.

4. (Build #2 type-check program): For those input files which have not
   "logically changed" (meaning components within are semantically the same
   as they were before), the compiler will re-use the type-check file
   metadata from build #1, and _not_ generate a new .ngtypecheck shim.
   For components which have logically changed or where the previous
   .ngtypecheck contents cannot otherwise be reused, code generation happens
   as before.

PR Close angular#36211
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2 participants