r343867 - Emit diagnostic note when calling an invalid function declaration.

[James Y Knight via cfe-commits]

Author: jyknight
Date: Fri Oct  5 10:49:48 2018
New Revision: 343867

URL: http://llvm.org/viewvc/llvm-project?rev=343867&view=rev
Log:
Emit diagnostic note when calling an invalid function declaration.

The comment said it was intentionally not emitting any diagnostic
because the declaration itself was already diagnosed. However,
everywhere else that wants to not emit a diagnostic without an extra
note emits note_invalid_subexpr_in_const_expr instead, which gets
suppressed later.

This was the only place which did not emit a diagnostic note.

Differential Revision: https://reviews.llvm.org/D52919

Modified:
    cfe/trunk/lib/AST/ExprConstant.cpp
    cfe/trunk/test/SemaCXX/enable_if.cpp

Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=343867&r1=343866&r2=343867&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Fri Oct  5 10:49:48 2018
@@ -4330,10 +4330,13 @@ static bool CheckConstexprFunction(EvalI
       Declaration->isConstexpr())
     return false;
 
-  // Bail out with no diagnostic if the function declaration itself is invalid.
-  // We will have produced a relevant diagnostic while parsing it.
-  if (Declaration->isInvalidDecl())
+  // Bail out if the function declaration itself is invalid.  We will
+  // have produced a relevant diagnostic while parsing it, so just
+  // note the problematic sub-expression.
+  if (Declaration->isInvalidDecl()) {
+    Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
     return false;
+  }
 
   // Can we evaluate this function call?
   if (Definition && Definition->isConstexpr() &&

Modified: cfe/trunk/test/SemaCXX/enable_if.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/enable_if.cpp?rev=343867&r1=343866&r2=343867&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/enable_if.cpp (original)
+++ cfe/trunk/test/SemaCXX/enable_if.cpp Fri Oct  5 10:49:48 2018
@@ -414,7 +414,8 @@ static_assert(templated<1>() == 1, "");
 
 template <int N> constexpr int callTemplated() { return templated<N>(); }
 
-constexpr int B = callTemplated<0>(); // expected-error{{initialized by a constant expression}} expected-error at -2{{no matching function for call to 'templated'}} expected-note{{in instantiation of function template}} expected-note at -9{{candidate disabled}}
+constexpr int B = 10 + // the carat for the error should be pointing to the problematic call (on the next line), not here.
+    callTemplated<0>(); // expected-error{{initialized by a constant expression}} expected-error at -3{{no matching function for call to 'templated'}} expected-note{{in instantiation of function template}} expected-note at -10{{candidate disabled}}
 static_assert(callTemplated<1>() == 1, "");
 }