Temporary fix for PR18473: Don't try to evaluate the initializer for a

type-dependent variable, even if the initializer isn't value-dependent. This
happens for ParenListExprs composed of non-value-dependent subexpressions, for
instance.

We should really give ParenListExprs (and InitListExprs) the type of the
initialized entity if they're used to represent a dependent initialization (and
if so, set them to be type-, value- and instantiation-dependent).

llvm-svn: 200954

clang/lib/Sema/SemaExprCXX.cpp

@@ -5815,17 +5815,16 @@ static inline bool VariableCanNeverBeAConstantExpression(VarDecl *Var,
   assert(DefVD);
   if (DefVD->isWeak()) return false;
   EvaluatedStmt *Eval = DefVD->ensureEvaluatedStmt();
-  
+
   Expr *Init = cast<Expr>(Eval->Value);
 
   if (Var->getType()->isDependentType() || Init->isValueDependent()) {
-    if (!Init->isValueDependent())
-      return !DefVD->checkInitIsICE();
-    // FIXME: We might still be able to do some analysis of Init here
-    // to conclude that even in a dependent setting, Init can never
-    // be a constexpr - but for now admit agnosticity.
+    // FIXME: Teach the constant evaluator to deal with the non-dependent parts
+    // of value-dependent expressions, and use it here to determine whether the
+    // initializer is a potential constant expression.
     return false;
-  } 
+  }
+
   return !IsVariableAConstantExpression(Var, Context); 
 }
 

clang/test/SemaCXX/lambda-expressions.cpp

@@ -344,3 +344,18 @@ namespace PR18128 {
     int d = []{ return [=]{ return n; }(); }(); // expected-error {{'this' cannot be implicitly captured in this context}}
   };
 }
+
+namespace PR18473 {
+  template<typename T> void f() {
+    T t(0);
+    (void) [=]{ int n = t; }; // expected-error {{deleted}}
+  }
+
+  template void f<int>();
+  struct NoCopy {
+    NoCopy(int);
+    NoCopy(const NoCopy &) = delete; // expected-note {{deleted}}
+    operator int() const;
+  };
+  template void f<NoCopy>(); // expected-note {{instantiation}}
+}