Fix crash on missing header in -rewrite-includes.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158459 91177308-0d34-0410-b5e6-96231b3b80d8

Author: dwblaikie

lib/Rewrite/InclusionRewriter.cpp

@@ -250,7 +250,8 @@ bool InclusionRewriter::Process(FileID FileId,
 {
   bool Invalid;
   const MemoryBuffer &FromFile = *SM.getBuffer(FileId, &Invalid);
-  assert(!Invalid && "Invalid FileID while trying to rewrite includes");
+  if (Invalid) // invalid inclusion
+    return true;
   const char *FileName = FromFile.getBufferIdentifier();
   Lexer RawLex(FileId, &FromFile, PP.getSourceManager(), PP.getLangOpts());
   RawLex.SetCommentRetentionState(false);

test/Frontend/rewrite-includes-missing.c

@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -verify -E -frewrite-includes %s -o - | FileCheck -strict-whitespace %s
+
+#include "foobar.h" // expected-error {{'foobar.h' file not found}}
+// CHECK: {{^}}#if 0 /* expanded by -frewrite-includes */{{$}}
+// CHECK-NEXT: {{^}}#include "foobar.h"
+// CHECK-NEXT: {{^}}#endif /* expanded by -frewrite-includes */{{$}}
+// CHECK-NEXT: {{^}}# 4 "/usr/local/google/home/blaikie/Development/llvm/src/tools/clang/test/Frontend/rewrite-includes-missing.c" 2{{$}}