From bf890dcb0f5eb05b1a98cbd1cdd24c0c4ece8f8d Mon Sep 17 00:00:00 2001
From: Haojian Wu <hokein.wu@gmail.com>
Date: Mon, 28 Sep 2020 15:08:28 +0200
Subject: [PATCH] [clang] Don't emit "no member" diagnostic if the lookup fails
 on an invalid record decl.

The "no member" diagnostic is likely bogus.

Reviewed By: sammccall, #libc

Differential Revision: https://reviews.llvm.org/D86765
---
 clang/lib/Sema/SemaExpr.cpp                        |  7 ++++++
 clang/test/SemaCXX/access-base-class.cpp           | 26 ++++++++++++++++++++++
 .../function_type_default_deleter.fail.cpp         |  2 --
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 9cd5a35..a7c0766 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -2581,6 +2581,13 @@ ExprResult Sema::BuildQualifiedDeclarationNameExpr(
                                      NameInfo, /*TemplateArgs=*/nullptr);
 
   if (R.empty()) {
+    // Don't diagnose problems with invalid record decl, the secondary no_member
+    // diagnostic during template instantiation is likely bogus, e.g. if a class
+    // is invalid because it's derived from an invalid base class, then missing
+    // members were likely supposed to be inherited.
+    if (const auto *CD = dyn_cast<CXXRecordDecl>(DC))
+      if (CD->isInvalidDecl())
+        return ExprError();
     Diag(NameInfo.getLoc(), diag::err_no_member)
       << NameInfo.getName() << DC << SS.getRange();
     return ExprError();
diff --git a/clang/test/SemaCXX/access-base-class.cpp b/clang/test/SemaCXX/access-base-class.cpp
index f676e19..2ed40ed 100644
--- a/clang/test/SemaCXX/access-base-class.cpp
+++ b/clang/test/SemaCXX/access-base-class.cpp
@@ -89,3 +89,29 @@ namespace T7 {
   };
 }
 
+namespace T8 {
+template <int>
+struct flag {
+  static constexpr bool value = true;
+};
+
+template <class T>
+struct trait : flag<sizeof(T)> {};
+
+template <class T, bool Inferred = trait<T>::value>
+struct a {};
+
+template <class T>
+class b {
+  a<T> x;
+  using U = a<T>;
+};
+
+template <int>
+struct Impossible {
+  static_assert(false, ""); // expected-error {{static_assert failed}}
+};
+
+// verify "no member named 'value'" bogus diagnostic is not emitted.
+trait<b<Impossible<0>>>::value;
+} // namespace T8
diff --git a/libcxx/test/libcxx/utilities/memory/util.smartptr/util.smartptr.shared/function_type_default_deleter.fail.cpp b/libcxx/test/libcxx/utilities/memory/util.smartptr/util.smartptr.shared/function_type_default_deleter.fail.cpp
index 0bba136..5727db6 100644
--- a/libcxx/test/libcxx/utilities/memory/util.smartptr/util.smartptr.shared/function_type_default_deleter.fail.cpp
+++ b/libcxx/test/libcxx/utilities/memory/util.smartptr/util.smartptr.shared/function_type_default_deleter.fail.cpp
@@ -45,8 +45,6 @@ int main(int, char**) {
     SPtr<3> s3(nullptr, Deleter{}); // OK
   }
   // expected-error-re@memory:* 2 {{static_assert failed{{.*}} "default_delete cannot be instantiated for function types"}}
-  // FIXME: suppress this bogus diagnostic, see https://reviews.llvm.org/D86685.
-  // expected-error@memory:* 0+ {{no member named 'value' in}}
   {
     SPtr<4> s4(getFn<4>()); // expected-note {{requested here}}
     SPtr<5> s5(getFn<5>(), std::default_delete<FnType<5>>{}); // expected-note {{requested here}}
-- 
2.7.4