[CrashReproducer] Setup 'use-external-names' in YAML files.

Hide the real paths when rebuilding from VFS by setting up the crash
reproducer to use 'use-external-names' = false. This way we avoid
module redifinition errors and consistently use the same paths against
all modules.

With this change on Darwin we are able to simulate a crash for a simple
application using "Foundation/Foundation.h" (which relies on a bunch of
different frameworks and headers) and successfully rebuild all the
modules by relying solely at the VFS overlay.

llvm-svn: 266234

2 files changed, 13 insertions, 4 deletions

diff --git a/clang/lib/Basic/VirtualFileSystem.cpp b/clang/lib/Basic/VirtualFileSystem.cpp
index dd41ed2651e..be7a637a73e 100644
--- a/clang/lib/Basic/VirtualFileSystem.cpp
+++ b/clang/lib/Basic/VirtualFileSystem.cpp
@@ -1504,8 +1504,9 @@ class JSONWriter {
 
 public:
   JSONWriter(llvm::raw_ostream &OS) : OS(OS) {}
-  void write(ArrayRef<YAMLVFSEntry> Entries, Optional<bool> IsCaseSensitive,
-             Optional<bool> IsOverlayRelative, StringRef OverlayDir);
+  void write(ArrayRef<YAMLVFSEntry> Entries, Optional<bool> UseExternalNames,
+             Optional<bool> IsCaseSensitive, Optional<bool> IsOverlayRelative,
+             StringRef OverlayDir);
 };
 }
 
@@ -1558,6 +1559,7 @@ void JSONWriter::writeEntry(StringRef VPath, StringRef RPath) {
 }
 
 void JSONWriter::write(ArrayRef<YAMLVFSEntry> Entries,
+                       Optional<bool> UseExternalNames,
                        Optional<bool> IsCaseSensitive,
                        Optional<bool> IsOverlayRelative,
                        StringRef OverlayDir) {
@@ -1568,6 +1570,9 @@ void JSONWriter::write(ArrayRef<YAMLVFSEntry> Entries,
   if (IsCaseSensitive.hasValue())
     OS << "  'case-sensitive': '"
        << (IsCaseSensitive.getValue() ? "true" : "false") << "',\n";
+  if (UseExternalNames.hasValue())
+    OS << "  'use-external-names': '"
+       << (UseExternalNames.getValue() ? "true" : "false") << "',\n";
   bool UseOverlayRelative = false;
   if (IsOverlayRelative.hasValue()) {
     UseOverlayRelative = IsOverlayRelative.getValue();
@@ -1629,8 +1634,8 @@ void YAMLVFSWriter::write(llvm::raw_ostream &OS) {
     return LHS.VPath < RHS.VPath;
   });
 
-  JSONWriter(OS).write(Mappings, IsCaseSensitive, IsOverlayRelative,
-                       OverlayDir);
+  JSONWriter(OS).write(Mappings, UseExternalNames, IsCaseSensitive,
+                       IsOverlayRelative, OverlayDir);
 }
 
 VFSFromYamlDirIterImpl::VFSFromYamlDirIterImpl(
diff --git a/clang/lib/Frontend/ModuleDependencyCollector.cpp b/clang/lib/Frontend/ModuleDependencyCollector.cpp
index 3e6c0d24750..02d3c515ef0 100644
--- a/clang/lib/Frontend/ModuleDependencyCollector.cpp
+++ b/clang/lib/Frontend/ModuleDependencyCollector.cpp
@@ -112,6 +112,10 @@ void ModuleDependencyCollector::writeFileMap() {
   // the sensitivity at the path where the headers all collected to.
   VFSWriter.setCaseSensitivity(isCaseSensitivePath(VFSDir));
 
+  // Do not rely on real path names when executing the crash reproducer scripts
+  // since we only want to actually use the files we have on the VFS cache.
+  VFSWriter.setUseExternalNames(false);
+
   std::error_code EC;
   SmallString<256> YAMLPath = VFSDir;
   llvm::sys::path::append(YAMLPath, "vfs.yaml");