[Sema][Comments] Add support for TypeAliasTemplate

Emit proper diagnostics when -Wdocumentation is used with constructs such as:

  template<typename T>
  using fn = int(T aaa, int ccc);

Previously clang wouldn't recognize the function and complain with
'comment that is not attached to a function declaration'.

Differential Revision: https://reviews.llvm.org/D23860

rdar://problem/27300695

llvm-svn: 279754

1 files changed, 14 insertions, 0 deletions

diff --git a/clang/lib/AST/Comment.cpp b/clang/lib/AST/Comment.cpp
index 307104224a6..7a7d3dd8304 100644
--- a/clang/lib/AST/Comment.cpp
+++ b/clang/lib/AST/Comment.cpp
@@ -310,6 +310,20 @@ void DeclInfo::fill() {
     Kind = TypedefKind;
     TemplateKind = Template;
     TemplateParameters = TAT->getTemplateParameters();
+    TypeAliasDecl *TAD = TAT->getTemplatedDecl();
+    if (!TAD)
+      break;
+
+    const TypeSourceInfo *TSI = TAD->getTypeSourceInfo();
+    if (!TSI)
+      break;
+    TypeLoc TL = TSI->getTypeLoc().getUnqualifiedLoc();
+    FunctionTypeLoc FTL;
+    if (getFunctionTypeLoc(TL, FTL)) {
+      Kind = FunctionKind;
+      ParamVars = FTL.getParams();
+      ReturnType = FTL.getReturnLoc().getType();
+    }
     break;
   }
   case Decl::Enum: