[VFS] Add 'ignore-non-existent-contents' field to YAML files

Add 'ignore-non-existent-contents' to tell the VFS whether an invalid path
obtained via 'external-contents' should cause iteration on the VFS to stop.

If 'true', the VFS should ignore the entry and continue with the next. Allows
YAML files to be shared across multiple compiler invocations regardless of
prior existent paths in 'external-contents'. This global value is overridable
on a per-file basis.

This adds the parsing and write test part, but use by VFS comes next.

Differential Revision: https://reviews.llvm.org/D23422

rdar://problem/27531549

llvm-svn: 278456

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/Frontend/ModuleDependencyCollector.cpp b/clang/lib/Frontend/ModuleDependencyCollector.cpp
index 11d36e55486..cc655f6eb00 100644
--- a/clang/lib/Frontend/ModuleDependencyCollector.cpp
+++ b/clang/lib/Frontend/ModuleDependencyCollector.cpp
@@ -134,6 +134,10 @@ void ModuleDependencyCollector::writeFileMap() {
   // allows crash reproducer scripts to work across machines.
   VFSWriter.setOverlayDir(VFSDir);
 
+  // Do not ignore non existent contents otherwise we might skip something
+  // that should have been collected here.
+  VFSWriter.setIgnoreNonExistentContents(false);
+
   // Explicitly set case sensitivity for the YAML writer. For that, find out
   // the sensitivity at the path where the headers all collected to.
   VFSWriter.setCaseSensitivity(isCaseSensitivePath(VFSDir));