[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

clang/include/clang/Frontend/PrecompiledPreamble.h

@@ -289,7 +289,6 @@ enum class BuildPreambleError {
   PreambleIsEmpty = 1,
   CouldntCreateTempFile,
   CouldntCreateTargetInfo,
-  CouldntCreateVFSOverlay,
   BeginSourceFileFailed,
   CouldntEmitPCH
 };

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));

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();

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;
 }

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:

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);

clang/test/VFS/Inputs/MissingVFS/a.h

@@ -0,0 +1 @@
+// void funcA(void);

clang/test/VFS/Inputs/MissingVFS/module.modulemap

@@ -0,0 +1,3 @@
+module A {
+  header "a.h"
+}

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'
+        }
+      ]
+    }
+  ]
+}

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();
+}