2019-11-27 Andrew Sutton <asutton@lock3software.com>
PR c++/92236
Defer evaluation of concept checks so that static assertions can
emit more detailed diagnostics.
gcc/cp/
* constexpr.c (cxx_eval_call_expression): Handle concept checks.
(cxx_eval_constant_expression): Diagnose misuse of function concepts
as template-id expressions. Follow the usual return path for results.
(cxx_eval_outermost_constant_expr): Avoid calling
cp_get_callee_fndecl_nofold for function concepts.
* constraint.cc (build_function_check): Fully type the concept check
so that we don't ICE in conversions.
* cp-gimplify.c (cp_genericize_r) [CALL_EXPR]: Handle concept checks.
[TEMPLATE_ID_EXPR] Likewise.
* cvt.c (convert_to_void): Always evaluate concept checks so we don't
accidentally ignore them. Substitution during satisfaction can make
a program ill-formed (example in g++.dg/cpp2a/concepts6.C).
* pt.c (tsubst_copy_and_build): [CALL_EXPR]: Don't evaluate concepts.
[TEMPLATE_ID_EXPR]: Likewise.
* semantics.c (finish_call_expr): Don't evaluate concepts.
(finish_id_expression_1): Likewise.
(finish_static_assert): Preserve the original condition so we can
diagnose concept errors when a check returns false.
gcc/testsuite/
* g++.dg/cpp2a/concepts-iconv1.C: Update diagnostics.
* g++.dg/cpp2a/concepts-requires5.C: Likewise.
* g++.dg/cpp2a/concepts6.C: New test.
From-SVN: r278775
