1 files changed, 18 insertions, 2 deletions
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 931766d..8411d00 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -3315,6 +3315,9 @@ static void GenerateHeaderSearchArgs(const HeaderSearchOptions &Opts,
   if (Opts.UseLibcxx)
     GenerateArg(Consumer, OPT_stdlib_EQ, "libc++");
 
+  if (!Opts.ModuleCachePath.empty())
+    GenerateArg(Consumer, OPT_fmodules_cache_path, Opts.ModuleCachePath);
+
   for (const auto &File : Opts.PrebuiltModuleFiles)
     GenerateArg(Consumer, OPT_fmodule_file, File.first + "=" + File.second);
 
@@ -3417,7 +3420,8 @@ static void GenerateHeaderSearchArgs(const HeaderSearchOptions &Opts,
 }
 
 static bool ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args,
-                                  DiagnosticsEngine &Diags) {
+                                  DiagnosticsEngine &Diags,
+                                  const std::string &WorkingDir) {
   unsigned NumErrorsBefore = Diags.getNumErrors();
 
   HeaderSearchOptions *HeaderSearchOpts = &Opts;
@@ -3430,6 +3434,17 @@ static bool ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args,
   if (const Arg *A = Args.getLastArg(OPT_stdlib_EQ))
     Opts.UseLibcxx = (strcmp(A->getValue(), "libc++") == 0);
 
+  // Canonicalize -fmodules-cache-path before storing it.
+  SmallString<128> P(Args.getLastArgValue(OPT_fmodules_cache_path));
+  if (!(P.empty() || llvm::sys::path::is_absolute(P))) {
+    if (WorkingDir.empty())
+      llvm::sys::fs::make_absolute(P);
+    else
+      llvm::sys::fs::make_absolute(WorkingDir, P);
+  }
+  llvm::sys::path::remove_dots(P);
+  Opts.ModuleCachePath = std::string(P);
+
   // Only the -fmodule-file=<name>=<file> form.
   for (const auto *A : Args.filtered(OPT_fmodule_file)) {
     StringRef Val = A->getValue();
@@ -5006,7 +5021,8 @@ bool CompilerInvocation::CreateFromArgsImpl(
   InputKind DashX = Res.getFrontendOpts().DashX;
   ParseTargetArgs(Res.getTargetOpts(), Args, Diags);
   llvm::Triple T(Res.getTargetOpts().Triple);
-  ParseHeaderSearchArgs(Res.getHeaderSearchOpts(), Args, Diags);
+  ParseHeaderSearchArgs(Res.getHeaderSearchOpts(), Args, Diags,
+                        Res.getFileSystemOpts().WorkingDir);
   if (Res.getFrontendOpts().GenReducedBMI ||
       Res.getFrontendOpts().ProgramAction ==
           frontend::GenerateReducedModuleInterface ||