AST dumping: dump template instantiations only once

Fixes infinite loop in PR15220.

Patch by Philip Craig.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175805 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ASTDumper.cpp b/lib/AST/ASTDumper.cpp
index cdc96b6..7401530 100644
--- a/lib/AST/ASTDumper.cpp
+++ b/lib/AST/ASTDumper.cpp
@@ -947,7 +947,10 @@
     case TSK_ImplicitInstantiation:
     case TSK_ExplicitInstantiationDeclaration:
     case TSK_ExplicitInstantiationDefinition:
-      dumpDecl(*I);
+      if (D == D->getCanonicalDecl())
+        dumpDecl(*I);
+      else
+        dumpDeclRef(*I);
       break;
     case TSK_ExplicitSpecialization:
       dumpDeclRef(*I);
@@ -973,7 +976,10 @@
     switch (I->getTemplateSpecializationKind()) {
     case TSK_Undeclared:
     case TSK_ImplicitInstantiation:
-      dumpDecl(*I);
+      if (D == D->getCanonicalDecl())
+        dumpDecl(*I);
+      else
+        dumpDeclRef(*I);
       break;
     case TSK_ExplicitSpecialization:
     case TSK_ExplicitInstantiationDeclaration: