feat(@ngtools/webpack): show warning when a TS compilations contains …

[alan-agius4]

…unused files

When a tsconfig without includes or files all files under the rootDir will be included in the compilation. This results in redundant files to inserted as part of the ts compilation which in some cases might reduce the compilation drastically.

Related to: TOOL-949

[alan-agius4]

Note: tests to be added

Also without implementing this #15030 for VE the warning will be shown all the time for newly generated apps.

This is because by default we do include redundant files in the compilations. There are;

• app.server.module.ts
• server.ts
• main.server.ts
• environment.prod.ts

NB: All existing projects will have this warning.

[clydin]

We may want to ignore anything involved in file replacements.

[alan-agius4]

Only the last one, is in fileReplacement but, why should we ignore it? It is in the compilation because of the non strict includes that we currently have as otherwise they won’t be part of the compilation.

[alan-agius4]

As discussed we should only enable this for Ivy.

[filipesilva]

I like how this ended up not requiring a lot of changes.

Most of my change requests are actually questions.

[filipesilva]

Somewhat reluctant on adding to the list here. I agree that it's a convenient place to hook into, but it adds somewhat unrelated things to the mental model for this call.

Would this approach work as well if added to getCompiledFile instead (assuming adding imports is not needed either)?

[alan-agius4]

Agreed

[alan-agius4]

Just checked and getCompiledFile will not be called for all files, such as type only files.

So if we want to remove this from here, what we can do is to expose the _usedSourceFiles publicly and from the loader in https://github.com/angular/angular-cli/blob/master/packages/ngtools/webpack/src/loader.ts#L77 we do:
Ex:

        [...new Set(dependencies)].forEach(dep => {
          plugin.updateChangedFileExtensions(path.extname(dep));
          this.addDependency(dep);
          plugin.usedSourceFiles.add(forwardSlashPath(fileName));
        });

[clydin]

What about adding an additional Webpack compilation hook inside the Angular plugin that compares the set of TS source files with webpack modules? Not sure of the appropriate hook off the top of my head though.

[alan-agius4]

That’s sound like a good idea I think the hook was called finishedModules or something like that.

[alan-agius4]

@clydin I tried the above, but the problem is that type only files will not be part of the webpack modules.

[alan-agius4]

Managed to get the information needed through buildInfo.

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