Index: lib/Serialization/ASTReader.cpp =================================================================== --- lib/Serialization/ASTReader.cpp +++ lib/Serialization/ASTReader.cpp @@ -1220,6 +1220,7 @@ // Parse the file names std::map FileIDs; + FileIDs[-1] = -1; // For unspecified filenames. for (unsigned I = 0; Record[Idx]; ++I) { // Extract the file name auto Filename = ReadPath(F, Record, Idx); Index: lib/Serialization/ASTWriter.cpp =================================================================== --- lib/Serialization/ASTWriter.cpp +++ lib/Serialization/ASTWriter.cpp @@ -2363,12 +2363,13 @@ // Emit the needed file names. llvm::DenseMap FilenameMap; + FilenameMap[-1] = -1; // For unspecified filenames. for (const auto &L : LineTable) { if (L.first.ID < 0) continue; for (auto &LE : L.second) { if (FilenameMap.insert(std::make_pair(LE.FilenameID, - FilenameMap.size())).second) + FilenameMap.size() - 1)).second) AddPath(LineTable.getFilename(LE.FilenameID), Record); } } Index: test/PCH/line-directive-nofilename.h =================================================================== --- test/PCH/line-directive-nofilename.h +++ test/PCH/line-directive-nofilename.h @@ -0,0 +1,5 @@ +#line 42 +int foo; // This should appear as at line-directive-nofilename.h:42 + +#line 100 "foobar.h" +int bar; // This should appear as at foobar.h:100 Index: test/PCH/line-directive-nofilename.c =================================================================== --- test/PCH/line-directive-nofilename.c +++ test/PCH/line-directive-nofilename.c @@ -0,0 +1,9 @@ +// RUN: %clang_cc1 -emit-pch -o %t %S/line-directive-nofilename.h +// RUN: not %clang_cc1 -include-pch %t -fsyntax-only %s 2>&1 | FileCheck %s + +// This causes an "error: redefinition" diagnostic. The notes will have the +// locations of the declarations from the PCH file. +double foo, bar; + +// CHECK: line-directive-nofilename.h:42:5: note: previous definition is here +// CHECK: foobar.h:100:5: note: previous definition is here