Author: faisalv
Date: Tue Nov 17 22:29:22 2015
New Revision: 253431
URL: http://llvm.org/viewvc/llvm-project?rev=253431&view=rev
Log:
[NFC] Change the evaluation context of a non-type default template argument
from Unevaluated to ConstantEvaluated.
This patch emits a more appropriate (but still noisy) diagnostic stream when a
lambda-expression is encountered within a non-type default argument.
For e.g. template<int N = ([] { return 5; }())> int f();
As opposed to complaining that a lambda expression is not allowed in an
unevaluated operand, the patch complains about the lambda being forbidden in a
constant expression context (which will be allowed in C++17 now that they have
been accepted by EWG, unless of course CWG or national bodies (that have so far
shown no signs of concern) rise in protest)
As I start submitting patches for constexpr lambdas (http://wg21.link/P0170R0)
under C++1z (OK'd by Richard Smith at Kona), this will be one less change to
make.
Thanks!
Modified:
cfe/trunk/lib/Parse/ParseTemplate.cpp
cfe/trunk/test/CXX/temp/temp.arg/temp.arg.nontype/p1.cpp
Modified: cfe/trunk/lib/Parse/ParseTemplate.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseTemplate.cpp?rev=253431&r1=253430&r2=253431&view=diff
==============================================================================
--- cfe/trunk/lib/Parse/ParseTemplate.cpp (original)
+++ cfe/trunk/lib/Parse/ParseTemplate.cpp Tue Nov 17 22:29:22 2015
@@ -695,7 +695,8 @@ Parser::ParseNonTypeTemplateParameter(un
// end of the template-parameter-list rather than a greater-than
// operator.
GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
- EnterExpressionEvaluationContext Unevaluated(Actions, Sema::Unevaluated);
+ EnterExpressionEvaluationContext Unevaluated(Actions,
+ Sema::ConstantEvaluated);
DefaultArg =
Actions.CorrectDelayedTyposInExpr(ParseAssignmentExpression());
if (DefaultArg.isInvalid())
Modified: cfe/trunk/test/CXX/temp/temp.arg/temp.arg.nontype/p1.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/temp/temp.arg/temp.arg.nontype/p1.cpp?rev=253431&r1=253430&r2=253431&view=diff
==============================================================================
--- cfe/trunk/test/CXX/temp/temp.arg/temp.arg.nontype/p1.cpp (original)
+++ cfe/trunk/test/CXX/temp/temp.arg/temp.arg.nontype/p1.cpp Tue Nov 17
22:29:22 2015
@@ -1,4 +1,5 @@
// RUN: %clang_cc1 -fsyntax-only -verify -triple=x86_64-linux-gnu %s
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -triple=x86_64-linux-gnu
%s -DCPP11ONLY
// C++11 [temp.arg.nontype]p1:
//
@@ -6,6 +7,8 @@
// be one of:
// -- an integral constant expression; or
// -- the name of a non-type template-parameter ; or
+#ifndef CPP11ONLY
+
namespace non_type_tmpl_param {
template <int N> struct X0 { X0(); };
template <int N> X0<N>::X0() { }
@@ -95,3 +98,14 @@ namespace bad_args {
int* iptr = &i;
X0<iptr> x0b; // expected-error{{non-type template argument for template
parameter of pointer type 'int *' must have its address taken}}
}
+#endif // CPP11ONLY
+
+namespace default_args {
+#ifdef CPP11ONLY
+namespace lambdas {
+template<int I = ([] { return 5; }())> //expected-error 2{{constant
expression}} expected-note{{constant expression}}
+int f();
+}
+#endif // CPP11ONLY
+
+}
\ No newline at end of file
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