c++: Fix ICE with { } as template argument [PR94592]
As an extension (there should be a CWG about this though), we support braced-init-list as a template argument, but convert_nontype_argument had trouble digesting them. We ICEd because of the double coercion we perform for template arguments: convert_nontype_argument called from finish_template_type got a { }, and since a class type was involved and we were in a template, convert_like created an IMPLICIT_CONV_EXPR. Then the second conversion of the same argument crashed in constexpr.c because the IMPLICIT_CONV_EXPR had gotten wrapped in a TARGET_EXPR. Another issue was that an IMPLICIT_CONV_EXPR leaked to constexpr.c when building an aggregate init. We should have instantiated the IMPLICIT_CONV_EXPR in the first call to convert_nontype_argument, but we didn't, because the call to is_nondependent_constant_expression returned false because it checks !BRACE_ENCLOSED_INITIALIZER_P. Then non_dep was false even though the expression didn't contain anything dependent and we didn't instantiate it in convert_nontype_argument. To fix this, check BRACE_ENCLOSED_INITIALIZER_P in cxx_eval_outermost_constant_expr rather than in is_nondependent_*. PR c++/94592 * constexpr.c (cxx_eval_outermost_constant_expr): Return when T is a BRACE_ENCLOSED_INITIALIZER_P. (is_nondependent_constant_expression): Don't check BRACE_ENCLOSED_INITIALIZER_P. (is_nondependent_static_init_expression): Likewise. * g++.dg/cpp2a/nontype-class34.C: New test. * g++.dg/cpp2a/nontype-class35.C: New test.
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2020-04-17 Marek Polacek <polacek@redhat.com>
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PR c++/94592
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* constexpr.c (cxx_eval_outermost_constant_expr): Return when T is
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a BRACE_ENCLOSED_INITIALIZER_P.
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(is_nondependent_constant_expression): Don't check
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BRACE_ENCLOSED_INITIALIZER_P.
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(is_nondependent_static_init_expression): Likewise.
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2020-04-20 Patrick Palka <ppalka@redhat.com>
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PR c++/94628
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@ -6534,6 +6534,12 @@ cxx_eval_outermost_constant_expr (tree t, bool allow_non_constant,
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bool non_constant_p = false;
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bool overflow_p = false;
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if (BRACE_ENCLOSED_INITIALIZER_P (t))
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{
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gcc_checking_assert (allow_non_constant);
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return t;
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}
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constexpr_global_ctx global_ctx;
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constexpr_ctx ctx = { &global_ctx, NULL, NULL, NULL, NULL, NULL, NULL,
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allow_non_constant, strict,
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@ -8295,7 +8301,6 @@ bool
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is_nondependent_constant_expression (tree t)
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{
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return (!type_unknown_p (t)
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&& !BRACE_ENCLOSED_INITIALIZER_P (t)
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&& is_constant_expression (t)
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&& !instantiation_dependent_expression_p (t));
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}
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@ -8307,7 +8312,6 @@ bool
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is_nondependent_static_init_expression (tree t)
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{
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return (!type_unknown_p (t)
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&& !BRACE_ENCLOSED_INITIALIZER_P (t)
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&& is_static_init_expression (t)
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&& !instantiation_dependent_expression_p (t));
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}
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@ -1,3 +1,9 @@
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2020-04-17 Marek Polacek <polacek@redhat.com>
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PR c++/94592
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* g++.dg/cpp2a/nontype-class34.C: New test.
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* g++.dg/cpp2a/nontype-class35.C: New test.
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2020-04-20 Patrick Palka <ppalka@redhat.com>
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PR c++/94628
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@ -0,0 +1,16 @@
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// PR c++/94592 - ICE with { } as template argument.
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// { dg-do compile { target c++2a } }
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struct A {
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constexpr A() {}
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};
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template <A> struct B { };
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template<typename> void bar () {
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B<{}> var;
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}
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void fu() {
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bar<int>();
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}
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// PR c++/94592 - ICE with { } as template argument.
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// { dg-do compile { target c++2a } }
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struct A {
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int i;
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constexpr A(int n) : i(n) {}
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};
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template <A a> struct B { int i; constexpr B() : i(a.i) { } };
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template<typename> void bar () {
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B<{1}> var;
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}
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void fu() {
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bar<int>();
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}
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