[clang][deps] Remove '-fmodules-cache-path=' arguments

With explicit modules build, the '-fmodules-cache-path=' argument is unused.

This patch removes the argument to avoid warnings or errors (with '-Werror') stemming from that.

Depends on D118915.

Reviewed By: dexonsmith

Differential Revision: https://reviews.llvm.org/D120474

clang/lib/Tooling/DependencyScanning/DependencyScanningTool.cpp

@@ -31,7 +31,13 @@ FullDependencies::getCommandLineWithoutModulePaths() const {
       getAdditionalArgsWithoutModulePaths();
   Args.insert(Args.end(), AdditionalArgs.begin(), AdditionalArgs.end());
 
-  // TODO: Filter out implicit modules leftovers (e.g. "-fmodules-cache-path=").
+  // This argument is unused in explicit compiles.
+  llvm::erase_if(Args, [](const std::string &Arg) {
+    return Arg.find("-fmodules-cache-path=") == 0;
+  });
+
+  // TODO: Filter out the remaining implicit modules leftovers
+  // (e.g. "-fmodules-prune-interval=" or "-fmodules-prune-after=").
 
   return Args;
 }

clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp

@@ -51,6 +51,7 @@ CompilerInvocation ModuleDepCollector::makeInvocationForModuleBuildWithoutPaths(
 
   CI.getLangOpts()->ImplicitModules = false;
   CI.getHeaderSearchOpts().ImplicitModuleMaps = false;
+  CI.getHeaderSearchOpts().ModuleCachePath.clear();
 
   // Report the prebuilt modules this module uses.
   for (const auto &PrebuiltModule : Deps.PrebuiltModuleDeps)

clang/test/ClangScanDeps/modules-inferred-explicit-build.m

@@ -12,7 +12,7 @@
 // RUN: %python %S/../../utils/module-deps-to-rsp.py %t.db --tu-index=0 > %t.tu.rsp
 // RUN: %clang @%t.inferred.cc1.rsp -pedantic -Werror
 // RUN: %clang @%t.system.cc1.rsp -pedantic -Werror
-// RUN: %clang @%t.tu.rsp -pedantic -Werror -Wno-unused-command-line-argument
+// RUN: %clang @%t.tu.rsp -pedantic -Werror
 
 #include <Inferred/Inferred.h>
 #include <System/System.h>

clang/tools/clang-scan-deps/ClangScanDeps.cpp

@@ -374,11 +374,11 @@ private:
     const ModuleDeps &MD = MDIt->second;
 
     StringRef Filename = llvm::sys::path::filename(MD.ImplicitModulePCMPath);
+    StringRef ModuleCachePath = llvm::sys::path::parent_path(
+        llvm::sys::path::parent_path(MD.ImplicitModulePCMPath));
 
-    SmallString<256> ExplicitPCMPath(
-        !ModuleFilesDir.empty()
-            ? ModuleFilesDir
-            : MD.BuildInvocation.getHeaderSearchOpts().ModuleCachePath);
+    SmallString<256> ExplicitPCMPath(!ModuleFilesDir.empty() ? ModuleFilesDir
+                                                             : ModuleCachePath);
     llvm::sys::path::append(ExplicitPCMPath, MD.ID.ContextHash, Filename);
     return std::string(ExplicitPCMPath);
   }