PR19623: Implement typedefs of void.

This the LLVM portion that will allow Clang and other frontends to emit
typedefs of void by providing a null type for the typedef's underlying
type.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207777 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 32 insertions, 1 deletions

diff --git a/lib/IR/DIBuilder.cpp b/lib/IR/DIBuilder.cpp
index 8dd5165eb2..8d7d21eb16 100644
--- a/lib/IR/DIBuilder.cpp
+++ b/lib/IR/DIBuilder.cpp
@@ -355,7 +355,6 @@ DIDerivedType DIBuilder::createReferenceType(unsigned Tag, DIType RTy) {
 DIDerivedType DIBuilder::createTypedef(DIType Ty, StringRef Name, DIFile File,
                                        unsigned LineNo, DIDescriptor Context) {
   // typedefs are encoded in DIDerivedType format.
-  assert(Ty.isType() && "Invalid typedef type!");
   Value *Elts[] = {
     GetTagConstant(VMContext, dwarf::DW_TAG_typedef),
     File.getFileNode(),
diff --git a/test/DebugInfo/typedef.ll b/test/DebugInfo/typedef.ll
new file mode 100644
index 0000000000..6f8a4462dd
--- /dev/null
+++ b/test/DebugInfo/typedef.ll
@@ -0,0 +1,32 @@
+; REQUIRES: object-emission
+
+; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump -debug-dump=info - | FileCheck %s
+
+; From source:
+; typedef void x;
+; x *y;
+
+; Check that a typedef with no DW_TAG_type is produced. The absence of a type is used to imply the 'void' type.
+
+; CHECK: DW_TAG_typedef
+; CHECK-NOT: DW_TAG_type
+; CHECK: {{DW_TAG|NULL}}
+
+@y = global i8* null, align 8
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!8, !9}
+!llvm.ident = !{!10}
+
+!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.5.0 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !2, metadata !3, metadata !2, metadata !"", i32 1} ; [ DW_TAG_compile_unit ] [/tmp/dbginfo/typedef.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"typedef.cpp", metadata !"/tmp/dbginfo"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786484, i32 0, null, metadata !"y", metadata !"y", metadata !"", metadata !5, i32 2, metadata !6, i32 0, i32 1, i8** @y, null} ; [ DW_TAG_variable ] [y] [line 2] [def]
+!5 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/tmp/dbginfo/typedef.cpp]
+!6 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 0, metadata !7} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from x]
+!7 = metadata !{i32 786454, metadata !1, null, metadata !"x", i32 1, i64 0, i64 0, i64 0, i32 0, null} ; [ DW_TAG_typedef ] [x] [line 1, size 0, align 0, offset 0] [from ]
+!8 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!9 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}
+!10 = metadata !{metadata !"clang version 3.5.0 "}
+