[clang][deps] Remove more codegen options

[jansvoboda11]

Summary

Codegen options are typically unused by modules. Reset some of them to increase sharing between TUs with different flags.

[Bigcheese]

lgtm. Although I wonder if long term we should add something to the option tablegen file for this case?

[jansvoboda11]

In D135720#3850954, @Bigcheese wrote:

lgtm. Although I wonder if long term we should add something to the option tablegen file for this case?

I think a good option would be to have a function that uses the information we already have in TableGen and sets the fields to their default values while respecting any derived values.

clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp

ModuleDepCollector::makeInvocationForModuleBuildWithoutOutputs(
   CI.resetNonModularOptions();
   CI.clearImplicitModuleBuildOptions();
 
   // Remove options incompatible with explicit module build or are likely to
   // differ between identical modules discovered from different translation
   // units.
   CI.getFrontendOpts().Inputs.clear();
   CI.getFrontendOpts().OutputFile.clear();
+
+  // TODO: Figure out better way to set options to their default value.
   CI.getCodeGenOpts().MainFileName.clear();
   CI.getCodeGenOpts().DwarfDebugFlags.clear();
+  if (!CI.getLangOpts()->ModulesCodegen) {
+    CI.getCodeGenOpts().DebugCompilationDir.clear();
+    CI.getCodeGenOpts().CoverageCompilationDir.clear();
+  }
+
   // Map output paths that affect behaviour to "-" so their existence is in the
   // context hash. The final path will be computed in addOutputPaths.
   if (!CI.getDiagnosticOpts().DiagnosticSerializationFile.empty())
     CI.getDiagnosticOpts().DiagnosticSerializationFile = "-";
   if (!CI.getDependencyOutputOpts().OutputFile.empty())
     CI.getDependencyOutputOpts().OutputFile = "-";
   CI.getDependencyOutputOpts().Targets.clear();
 

clang/test/ClangScanDeps/Inputs/removed-args/cdb.json.template

 [
   {
     "directory": "DIR",
-    "command": "clang -fsyntax-only DIR/tu.c -fmodules -fimplicit-module-maps -fmodules-validate-once-per-build-session -fbuild-session-file=DIR/build-session -fmodules-prune-interval=123 -fmodules-prune-after=123 -fmodules-cache-path=DIR/cache -include DIR/header.h -grecord-command-line -o DIR/tu.o -serialize-diagnostics DIR/tu.diag -MT tu -MD -MF DIR/tu.d",
+    "command": "clang -fsyntax-only DIR/tu.c -fmodules -fimplicit-module-maps -fmodules-validate-once-per-build-session -fbuild-session-file=DIR/build-session -fmodules-prune-interval=123 -fmodules-prune-after=123 -fmodules-cache-path=DIR/cache -include DIR/header.h -grecord-command-line -fdebug-compilation-dir=DIR/debug -fcoverage-compilation-dir=DIR/coverage -o DIR/tu.o -serialize-diagnostics DIR/tu.diag -MT tu -MD -MF DIR/tu.d",
     "file": "DIR/tu.c"
   }
 ]

clang/test/ClangScanDeps/removed-args.c

 //
 // CHECK:      {
 // CHECK-NEXT:   "modules": [
 // CHECK-NEXT:     {
 // CHECK-NEXT:       "clang-module-deps": [],
 // CHECK-NEXT:       "clang-modulemap-file": "[[PREFIX]]/module.modulemap",
 // CHECK-NEXT:       "command-line": [
 // CHECK-NEXT:         "-cc1"
+// CHECK-NOT:          "-fdebug-compilation-dir="
+// CHECK-NOT:          "-fcoverage-compilation-dir="
 // CHECK-NOT:          "-dwarf-debug-flags"
 // CHECK-NOT:          "-main-file-name"
 // CHECK-NOT:          "-include"
 // CHECK-NOT:          "-fmodules-cache-path=
 // CHECK-NOT:          "-fmodules-validate-once-per-build-session"
 // CHECK-NOT:          "-fbuild-session-timestamp=
 // CHECK-NOT:          "-fmodules-prune-interval=
 // CHECK-NOT:          "-fmodules-prune-after=
 // CHECK:            ],
 // CHECK-NEXT:       "context-hash": "[[HASH_MOD_HEADER:.*]]",
 // CHECK-NEXT:       "file-deps": [
 // CHECK-NEXT:         "[[PREFIX]]/mod_header.h",
 // CHECK-NEXT:         "[[PREFIX]]/module.modulemap"
 // CHECK-NEXT:       ],
 // CHECK-NEXT:       "name": "ModHeader"
 // CHECK-NEXT:     },
 // CHECK-NEXT:     {
 // CHECK-NEXT:       "clang-module-deps": [],
 // CHECK-NEXT:       "clang-modulemap-file": "[[PREFIX]]/module.modulemap",
 // CHECK-NEXT:       "command-line": [
 // CHECK-NEXT:         "-cc1"
+// CHECK-NOT:          "-fdebug-compilation-dir=
+// CHECK-NOT:          "-fcoverage-compilation-dir=
 // CHECK-NOT:          "-dwarf-debug-flags"
 // CHECK-NOT:          "-main-file-name"
 // CHECK-NOT:          "-include"
 // CHECK-NOT:          "-fmodules-cache-path=
 // CHECK-NOT:          "-fmodules-validate-once-per-build-session"
 // CHECK-NOT:          "-fbuild-session-timestamp=
 // CHECK-NOT:          "-fmodules-prune-interval=
 // CHECK-NOT:          "-fmodules-prune-after=