From: Bill Wendling <isanbard@gmail.com>
Date: Sun, 27 Jan 2019 07:24:03 +0000 (+0000)
Subject: Remove Expr sugar decorating the CXXUuidofExpr node.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=7906282d3afec5dfdc2b27943fd6c0309086c507;p=clang

Remove Expr sugar decorating the CXXUuidofExpr node.

Summary: Sugar, like ConstantExpr, causes an infinite expansion of the template object.

Reviewers: rsmith, aaron.ballman

Reviewed By: aaron.ballman

Subscribers: riccibruno, aaron.ballman, cfe-commits, tzik, rnk

Differential Revision: https://reviews.llvm.org/D57114

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@352307 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 54a01b7333..2e73096a9b 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -6308,7 +6308,7 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
       // -- a predefined __func__ variable
       if (auto *E = Value.getLValueBase().dyn_cast<const Expr*>()) {
         if (isa<CXXUuidofExpr>(E)) {
-          Converted = TemplateArgument(ArgResult.get());
+          Converted = TemplateArgument(ArgResult.get()->IgnoreImpCasts());
           break;
         }
         Diag(Arg->getBeginLoc(), diag::err_template_arg_not_decl_ref)
diff --git a/test/SemaCXX/PR40395.cpp b/test/SemaCXX/PR40395.cpp
new file mode 100644
index 0000000000..469c86d562
--- /dev/null
+++ b/test/SemaCXX/PR40395.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -std=c++17 -fms-extensions -triple=x86_64-pc-win32 -verify %s
+// expected-no-diagnostics
+
+// PR40395 - ConstantExpr shouldn't cause the template object to infinitely
+// expand.
+struct _GUID {};
+struct __declspec(uuid("{AAAAAAAA-AAAA-AAAA-AAAA-AAAAAAAAAAAA}")) B {};
+
+template <const _GUID* piid>
+struct A {
+  virtual void baz() { A<piid>(); }
+};
+
+void f() {
+  A<&__uuidof(B)>();
+}