From 4b219051a331d49c391fe452548bc220bcfe8ea3 Mon Sep 17 00:00:00 2001
From: serge-sans-paille <sguelton@redhat.com>
Date: Mon, 7 Jun 2021 17:14:43 +0200
Subject: [PATCH] Fix undeduced type assert

If the instantiation of a member variable makes it possible to
compute a previously undeduced type, we should use that piece of
information.

Fix bug#50590

Differential Revision: https://reviews.llvm.org/D103849
---
 clang/lib/AST/Expr.cpp                           |  8 ++++++--
 clang/test/CodeGenCXX/auto-variable-template.cpp | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 842b9c0..ebf8761 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -490,6 +490,8 @@ DeclRefExpr *DeclRefExpr::CreateEmpty(const ASTContext &Context,
 
 void DeclRefExpr::setDecl(ValueDecl *NewD) {
   D = NewD;
+  if (getType()->isUndeducedType())
+    setType(NewD->getType());
   setDependence(computeDependence(this, NewD->getASTContext()));
 }
 
@@ -1722,8 +1724,10 @@ MemberExpr *MemberExpr::CreateEmpty(const ASTContext &Context,
   return new (Mem) MemberExpr(EmptyShell());
 }
 
-void MemberExpr::setMemberDecl(ValueDecl *D) {
-  MemberDecl = D;
+void MemberExpr::setMemberDecl(ValueDecl *NewD) {
+  MemberDecl = NewD;
+  if (getType()->isUndeducedType())
+    setType(NewD->getType());
   setDependence(computeDependence(this));
 }
 
diff --git a/clang/test/CodeGenCXX/auto-variable-template.cpp b/clang/test/CodeGenCXX/auto-variable-template.cpp
index 79a145a..ae7154f3 100644
--- a/clang/test/CodeGenCXX/auto-variable-template.cpp
+++ b/clang/test/CodeGenCXX/auto-variable-template.cpp
@@ -12,3 +12,21 @@ int main() { vtemplate<int>(); }
 
 // CHECK: define{{.*}} i32 @main()
 // CHECK: call void @_ZNK1fclEv(%struct.f* {{[^,]*}} @_Z9vtemplateIiE)
+
+template <typename>
+struct pack {
+  template <typename T>
+  constexpr static auto some_boolean_cx_value = true;
+};
+
+auto usage() {
+  return pack<char>::some_boolean_cx_value<int>;
+}
+
+// CHECK: define{{.*}} i1 @_Z5usagev()
+
+auto otherusage() {
+  return pack<char>{}.some_boolean_cx_value<int>;
+}
+
+// CHECK: define{{.*}} i1 @_Z10otherusagev()
-- 
2.7.4