[vfs] Don't bail out after a missing -ivfsoverlay file

This make -ivfsoverlay behave more like other fatal errors (e.g. missing
-include file) by skipping the missing file instead of bailing out of
the whole compilation. This makes it possible for libclang to still
provide some functionallity as well as to correctly produce the fatal
error diagnostic (previously we lost the diagnostic in libclang since
there was no TU to tie it to).

rdar://33385423

llvm-svn: 328337

10 files changed, 48 insertions, 22 deletions

diff --git a/clang/include/clang/Frontend/PrecompiledPreamble.h b/clang/include/clang/Frontend/PrecompiledPreamble.h
index f1898f573ff..aa8fb82f340 100644
--- a/clang/include/clang/Frontend/PrecompiledPreamble.h
+++ b/clang/include/clang/Frontend/PrecompiledPreamble.h
@@ -289,7 +289,6 @@ enum class BuildPreambleError {
   PreambleIsEmpty = 1,
   CouldntCreateTempFile,
   CouldntCreateTargetInfo,
-  CouldntCreateVFSOverlay,
   BeginSourceFileFailed,
   CouldntEmitPCH
 };
diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index cd3664bd3fc..1247e8219ff 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -1354,7 +1354,6 @@ ASTUnit::getMainBufferWithPrecompiledPreamble(
       case BuildPreambleError::CouldntCreateTargetInfo:
       case BuildPreambleError::BeginSourceFileFailed:
       case BuildPreambleError::CouldntEmitPCH:
-      case BuildPreambleError::CouldntCreateVFSOverlay:
         // These erros are more likely to repeat, retry after some period.
         PreambleRebuildCounter = DefaultPreambleRebuildInterval;
         return nullptr;
@@ -1456,8 +1455,6 @@ ASTUnit::create(std::shared_ptr<CompilerInvocation> CI,
   ConfigureDiags(Diags, *AST, CaptureDiagnostics);
   IntrusiveRefCntPtr<vfs::FileSystem> VFS =
       createVFSFromCompilerInvocation(*CI, *Diags);
-  if (!VFS)
-    return nullptr;
   AST->Diagnostics = Diags;
   AST->FileSystemOpts = CI->getFileSystemOpts();
   AST->Invocation = std::move(CI);
@@ -1735,14 +1732,14 @@ ASTUnit *ASTUnit::LoadFromCommandLine(
   // Create the AST unit.
   std::unique_ptr<ASTUnit> AST;
   AST.reset(new ASTUnit(false));
+  AST->NumStoredDiagnosticsFromDriver = StoredDiagnostics.size();
+  AST->StoredDiagnostics.swap(StoredDiagnostics);
   ConfigureDiags(Diags, *AST, CaptureDiagnostics);
   AST->Diagnostics = Diags;
   AST->FileSystemOpts = CI->getFileSystemOpts();
   if (!VFS)
     VFS = vfs::getRealFileSystem();
   VFS = createVFSFromCompilerInvocation(*CI, *Diags, VFS);
-  if (!VFS)
-    return nullptr;
   AST->FileMgr = new FileManager(AST->FileSystemOpts, VFS);
   AST->PCMCache = new MemoryBufferCache;
   AST->OnlyLocalDecls = OnlyLocalDecls;
@@ -1752,8 +1749,6 @@ ASTUnit *ASTUnit::LoadFromCommandLine(
   AST->IncludeBriefCommentsInCodeCompletion
     = IncludeBriefCommentsInCodeCompletion;
   AST->UserFilesAreVolatile = UserFilesAreVolatile;
-  AST->NumStoredDiagnosticsFromDriver = StoredDiagnostics.size();
-  AST->StoredDiagnostics.swap(StoredDiagnostics);
   AST->Invocation = CI;
   if (ForSerialization)
     AST->WriterData.reset(new ASTWriterData(*AST->PCMCache));
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index bb8b8572fa7..a03e5df63aa 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -302,11 +302,9 @@ CompilerInstance::createDiagnostics(DiagnosticOptions *Opts,
 
 FileManager *CompilerInstance::createFileManager() {
   if (!hasVirtualFileSystem()) {
-    if (IntrusiveRefCntPtr<vfs::FileSystem> VFS =
-            createVFSFromCompilerInvocation(getInvocation(), getDiagnostics()))
-      setVirtualFileSystem(VFS);
-    else
-      return nullptr;
+    IntrusiveRefCntPtr<vfs::FileSystem> VFS =
+        createVFSFromCompilerInvocation(getInvocation(), getDiagnostics());
+    setVirtualFileSystem(VFS);
   }
   FileMgr = new FileManager(getFileSystemOpts(), VirtualFileSystem);
   return FileMgr.get();
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index c9d251f5b7f..acbe650b861 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -3073,16 +3073,15 @@ createVFSFromCompilerInvocation(const CompilerInvocation &CI,
         BaseFS->getBufferForFile(File);
     if (!Buffer) {
       Diags.Report(diag::err_missing_vfs_overlay_file) << File;
-      return IntrusiveRefCntPtr<vfs::FileSystem>();
+      continue;
     }
 
     IntrusiveRefCntPtr<vfs::FileSystem> FS = vfs::getVFSFromYAML(
         std::move(Buffer.get()), /*DiagHandler*/ nullptr, File);
-    if (!FS.get()) {
+    if (FS)
+      Overlay->pushOverlay(FS);
+    else
       Diags.Report(diag::err_invalid_vfs_overlay) << File;
-      return IntrusiveRefCntPtr<vfs::FileSystem>();
-    }
-    Overlay->pushOverlay(FS);
   }
   return Overlay;
 }
diff --git a/clang/lib/Frontend/PrecompiledPreamble.cpp b/clang/lib/Frontend/PrecompiledPreamble.cpp
index d761f6ee458..ddd7bda546f 100644
--- a/clang/lib/Frontend/PrecompiledPreamble.cpp
+++ b/clang/lib/Frontend/PrecompiledPreamble.cpp
@@ -303,8 +303,6 @@ llvm::ErrorOr<PrecompiledPreamble> PrecompiledPreamble::Build(
 
   VFS =
       createVFSFromCompilerInvocation(Clang->getInvocation(), Diagnostics, VFS);
-  if (!VFS)
-    return BuildPreambleError::CouldntCreateVFSOverlay;
 
   // Create a file manager object to provide access to and cache the filesystem.
   Clang->setFileManager(new FileManager(Clang->getFileSystemOpts(), VFS));
@@ -756,8 +754,6 @@ std::string BuildPreambleErrorCategory::message(int condition) const {
     return "Could not create temporary file for PCH";
   case BuildPreambleError::CouldntCreateTargetInfo:
     return "CreateTargetInfo() return null";
-  case BuildPreambleError::CouldntCreateVFSOverlay:
-    return "Could not create VFS Overlay";
   case BuildPreambleError::BeginSourceFileFailed:
     return "BeginSourceFile() return an error";
   case BuildPreambleError::CouldntEmitPCH:
diff --git a/clang/test/Index/missing_vfs.c b/clang/test/Index/missing_vfs.c
new file mode 100644
index 00000000000..61aedd41cfa
--- /dev/null
+++ b/clang/test/Index/missing_vfs.c
@@ -0,0 +1,6 @@
+// RUN: c-index-test -test-load-source local %s -ivfsoverlay %t/does-not-exist.yaml &> %t.out
+// RUN: FileCheck -check-prefix=STDERR %s < %t.out
+// STDERR: fatal error: virtual filesystem overlay file '{{.*}}' not found
+// RUN: FileCheck %s < %t.out
+// CHECK: missing_vfs.c:[[@LINE+1]]:6: FunctionDecl=foo:[[@LINE+1]]:6
+void foo(void);
diff --git a/clang/test/VFS/Inputs/MissingVFS/a.h b/clang/test/VFS/Inputs/MissingVFS/a.h
new file mode 100644
index 00000000000..892d837b10b
--- /dev/null
+++ b/clang/test/VFS/Inputs/MissingVFS/a.h
@@ -0,0 +1 @@
+// void funcA(void);
diff --git a/clang/test/VFS/Inputs/MissingVFS/module.modulemap b/clang/test/VFS/Inputs/MissingVFS/module.modulemap
new file mode 100644
index 00000000000..bbd9d674c94
--- /dev/null
+++ b/clang/test/VFS/Inputs/MissingVFS/module.modulemap
@@ -0,0 +1,3 @@
+module A {
+  header "a.h"
+}
diff --git a/clang/test/VFS/Inputs/MissingVFS/vfsoverlay.yaml b/clang/test/VFS/Inputs/MissingVFS/vfsoverlay.yaml
new file mode 100644
index 00000000000..49517a15908
--- /dev/null
+++ b/clang/test/VFS/Inputs/MissingVFS/vfsoverlay.yaml
@@ -0,0 +1,13 @@
+{
+  'version': 0,
+  'ignore-non-existent-contents': false,
+  'roots': [
+    { 'name': 'INPUT_DIR', 'type': 'directory',
+      'contents': [
+        { 'name': 'a.h', 'type': 'file',
+          'external-contents': 'OUT_DIR/a.h'
+        }
+      ]
+    }
+  ]
+}
diff --git a/clang/test/VFS/module_missing_vfs.m b/clang/test/VFS/module_missing_vfs.m
new file mode 100644
index 00000000000..4c4ee4dd896
--- /dev/null
+++ b/clang/test/VFS/module_missing_vfs.m
@@ -0,0 +1,16 @@
+// REQUIRES: shell
+// RUN: rm -rf %t && mkdir -p %t
+// RUN: echo "void funcA(void);" >> %t/a.h
+
+// RUN: not %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/mcp -I %S/Inputs/MissingVFS %s -fsyntax-only -ivfsoverlay %t/vfs.yaml 2>&1 | FileCheck %s -check-prefix=ERROR
+// ERROR: virtual filesystem overlay file '{{.*}}' not found
+// RUN: find %t/mcp -name "A-*.pcm" | count 1
+
+// RUN: sed -e "s:INPUT_DIR:%S/Inputs:g" -e "s:OUT_DIR:%t:g" %S/Inputs/MissingVFS/vfsoverlay.yaml > %t/vfs.yaml
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/mcp -I %S/Inputs/MissingVFS %s -fsyntax-only -ivfsoverlay %t/vfs.yaml
+// RUN: find %t/mcp -name "A-*.pcm" | count 1
+
+@import A;
+void test(void) {
+  funcA();
+}