[ms] Don't try to delay lookup for failures in SFINAE context (PR23823)

The underlying problem in PR23823 already existed before my recent change
in r239558, but that change made it worse (failing not only for undeclared
symbols, but also failed overload resolution). This makes Clang not try to
delay the lookup in SFINAE context. I assume no current code is relying on
SFINAE working with lookups that need to be delayed, because that never
seems to have worked.

Differential Revision: http://reviews.llvm.org/D10417

llvm-svn: 239639

diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 117ca13..f8610e0 100644 (file)
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -10750,7 +10750,8 @@ bool Sema::buildOverloadedCallSet(Scope *S, Expr *Fn,
   // functions, including those from argument-dependent lookup.
   AddOverloadedCallCandidates(ULE, Args, *CandidateSet);
 
-  if (getLangOpts().MSVCCompat && CurContext->isDependentContext() &&
+  if (getLangOpts().MSVCCompat &&
+      CurContext->isDependentContext() && !isSFINAEContext() &&
       (isa<FunctionDecl>(CurContext) || isa<CXXRecordDecl>(CurContext))) {
 
     OverloadCandidateSet::iterator Best;

diff --git a/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp b/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
index 90e9f0a..9fa59e6 100644 (file)
--- a/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
+++ b/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
@@ -563,3 +563,13 @@ void test() {
   x.member(); // expected-note{{requested here}}
 };
 }
+
+namespace PR23823 {
+// Don't delay lookup in SFINAE context.
+template <typename T> decltype(g(T())) check(); // expected-note{{candidate template ignored: substitution failure [with T = int]: use of undeclared identifier 'g'}}
+decltype(check<int>()) x; // expected-error{{no matching function for call to 'check'}}
+
+void h();
+template <typename T> decltype(h(T())) check2(); // expected-note{{candidate template ignored: substitution failure [with T = int]: no matching function for call to 'h'}}
+decltype(check2<int>()) y; // expected-error{{no matching function for call to 'check2'}}
+}