[DebugInfo] Use SplitTemplateClosers (foo<bar<baz> >) in DWARF too

[sammccall]

Summary

D76801 caused some regressions in debuginfo compatibility by changing how
certain functions were named.

For CodeView we try to mirror MSVC exactly: this was fixed in a549c0d00486
For DWARF the situation is murkier. Per David Blaikie:

In general DWARF doesn't specify this at all.
[...]
This isn't the only naming divergence between GCC and Clang

Nevertheless, including the space seems to provide better compatibility with
GCC and GDB. E.g. cpexprs.cc in the GDB testsuite requires this formatting.
And there was no particular desire to change the printing of names in debug
info in the first place (just in diagnostics and other more user-facing text).

Fixes PR46052

[dblaikie]

Looks good - thanks!

[amccarth]

clang/lib/CodeGen/CGDebugInfo.cpp

242

So, in other words, we'll always set PP.SplitTemplateClosers to true, now.

[sammccall]

clang/lib/CodeGen/CGDebugInfo.cpp

242

Yes. I thought it was clearest to write it separately in each branch, as it's basically a coincidence and I can give a separate comment.

Happy to fold it together if you think it's confusing.

[amccarth]

clang/lib/CodeGen/CGDebugInfo.cpp

242

No change necessary. I agree with how you've done it. I was just amused that, after fixing the regression for CodeView, it ended up being undone for DWARF as well.

clang/lib/CodeGen/CGDebugInfo.cpp

PrintingPolicy CGDebugInfo::getPrintingPolicy() const {
   // If we're emitting codeview, it's important to try to match MSVC's naming so
   // that visualizers written for MSVC will trigger for our class names. In
   // particular, we can't have spaces between arguments of standard templates
   // like basic_string and vector, but we must have spaces between consecutive
   // angle brackets that close nested template argument lists.
   if (CGM.getCodeGenOpts().EmitCodeView) {
     PP.MSVCFormatting = true;
     PP.SplitTemplateClosers = true;
+  } else {
+    // For DWARF, printing rules are underspecified.
+    // SplitTemplateClosers yields better interop with GCC and GDB (PR46052).
+    PP.SplitTemplateClosers = true;
   }
 
   // Apply -fdebug-prefix-map.
   PP.Callbacks = &PrintCB;
   return PP;
 }
 
 StringRef CGDebugInfo::getFunctionName(const FunctionDecl *FD) {

clang/test/CodeGenCXX/debug-info-template-explicit-specialization.cpp

 };
 extern template class j<int>;
 j<int> jj;
 template <typename T>
 struct j_wrap {
 };
 j_wrap<j<int>> j_wrap_j;
 // CHECK: DICompositeType(tag: DW_TAG_structure_type, name: "j<int, int>"
-// CHECK: DICompositeType(tag: DW_TAG_structure_type, name: "j_wrap<j<int, int>>"
+// CHECK: DICompositeType(tag: DW_TAG_structure_type, name: "j_wrap<j<int, int> >"
 
 template <typename T>
 struct k {
 };
 template <>
 struct k<int>;
 template struct k<int>;
 // CHECK-NOT: !DICompositeType(tag: DW_TAG_structure_type, name: "k<int>"
 
 // CHECK: DICompositeType(tag: DW_TAG_structure_type, name: "b<int>"
 // CHECK-NOT: DIFlagFwdDecl
 // CHECK-SAME: ){{$}}

clang/test/Modules/ExtDebugInfo.cpp

 // CHECK-SAME:             flags: DIFlagFwdDecl
 // CHECK-SAME:             identifier:  "_ZTSN8DebugCXX4EnumE")
 
 // CHECK: ![[NS]] = !DINamespace(name: "DebugCXX", scope: ![[MOD:[0-9]+]])
 // CHECK: ![[MOD]] = !DIModule(scope: null, name: {{.*}}DebugCXX
 
 // This type is not anchored in the module by an explicit template instantiation.
 // CHECK: !DICompositeType(tag: DW_TAG_class_type,
-// CHECK-SAME:             name: "Template<long, DebugCXX::traits<long>>",
+// CHECK-SAME:             name: "Template<long, DebugCXX::traits<long> >",
 // CHECK-SAME:             scope: ![[NS]],
 // CHECK-SAME:             elements:
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX8TemplateIlNS_6traitsIlEEEE")
 
 // This type is anchored in the module by an explicit template instantiation.
 // CHECK: !DICompositeType(tag: DW_TAG_class_type,
-// CHECK-SAME:             name: "Template<int, DebugCXX::traits<int>>",
+// CHECK-SAME:             name: "Template<int, DebugCXX::traits<int> >",
 // CHECK-SAME:             scope: ![[NS]],
 // CHECK-SAME:             flags: DIFlagFwdDecl
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX8TemplateIiNS_6traitsIiEEEE")
 
 // This type isn't, however, even with standalone non-module debug info this
 // type is a forward declaration.
 // CHECK-NOT: !DICompositeType(tag: DW_TAG_structure_type, name: "traits<int>",
 
 // This one isn't.
 // CHECK: !DICompositeType(tag: DW_TAG_class_type,
-// CHECK-SAME:             name: "Template<float, DebugCXX::traits<float>>",
+// CHECK-SAME:             name: "Template<float, DebugCXX::traits<float> >",
 // CHECK-SAME:             scope: ![[NS]],
 // CHECK-SAME:             elements:
 // CHECK-SAME:             templateParams:
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX8TemplateIfNS_6traitsIfEEEE")
 
 // This type is anchored in the module by an explicit template instantiation.
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "traits<float>",
 // CHECK-SAME:             flags: DIFlagFwdDecl

clang/test/Modules/ModuleDebugInfo.cpp

 // CHECK-SAME:             templateParams:
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX1AIJvEEE")
 
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "Struct"
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX6StructE")
 
 // This type is anchored by an explicit template instantiation.
 // CHECK: !DICompositeType(tag: DW_TAG_class_type,
-// CHECK-SAME:             name: "Template<int, DebugCXX::traits<int>>"
+// CHECK-SAME:             name: "Template<int, DebugCXX::traits<int> >"
 // CHECK-SAME:             elements:
 // CHECK-SAME:             templateParams:
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX8TemplateIiNS_6traitsIiEEEE")
 
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "traits<int>"
 // CHECK-SAME:             flags: DIFlagFwdDecl
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX6traitsIiEE")
 
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "traits<float>"
 // CHECK-SAME:             elements:
 // CHECK-SAME:             templateParams:
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX6traitsIfEE")
 
 // CHECK: !DICompositeType(tag: DW_TAG_class_type,
-// CHECK-SAME:             name: "Template<long, DebugCXX::traits<long>>"
+// CHECK-SAME:             name: "Template<long, DebugCXX::traits<long> >"
 // CHECK-SAME:             elements:
 // CHECK-SAME:             templateParams:
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX8TemplateIlNS_6traitsIlEEEE")
 
 // CHECK: !DIDerivedType(tag: DW_TAG_typedef, name: "FloatInstantiation"
 // no mangled name here yet.
 
 // CHECK: !DICompositeType(tag: DW_TAG_class_type,
-// CHECK-SAME:             name: "Template<float, DebugCXX::traits<float>>"
+// CHECK-SAME:             name: "Template<float, DebugCXX::traits<float> >"
 // CHECK-SAME:             flags: DIFlagFwdDecl
 // CHECK-SAME:             identifier: "_ZTSN8DebugCXX8TemplateIfNS_6traitsIfEEEE")
 
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "Virtual"
 // CHECK-SAME:             elements:
 // CHECK-SAME:             identifier: "_ZTS7Virtual")
 // CHECK: !DIDerivedType(tag: DW_TAG_member, name: "_vptr$Virtual"