05708d6eef
In the testcase below, we're crashing during constraint checking of the implicitly generated deduction guides for the nested class template A::B because we never substitute the outer template arguments (for A) into the constraint, neither ahead of time nor as part of satisfaction. Ideally we'd like to avoid substituting into a constraint ahead of time, but the "flattening" vector 'tsubst_args' is constructed under the assumption that all outer template arguments are already substituted in, and eliminating this assumption to yield a flattening vector that includes outer (generic) template arguments suitable for substituting into the constraint would be tricky and error-prone. So this patch takes the approximate approach of substituting the outer arguments into the constraint ahead of time, so that the subsequent substitution of 'tsubst_args' is coherent and so later satisfaction just works. gcc/cp/ChangeLog: PR c++/97679 * pt.c (build_deduction_guide): Document OUTER_ARGS. Substitute them into the propagated constraints. gcc/testsuite/ChangeLog: PR c++/97679 * g++.dg/cpp2a/concepts-ctad3.C: New test.
17 lines
417 B
C
17 lines
417 B
C
// PR c++/97679
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// { dg-do compile { target c++20 } }
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template <bool V> struct A {
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template <class T> struct B {
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B(T) requires V;
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template <class U> B(T, U) requires V || (__is_same(T, char) && __is_same(U, int));
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};
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};
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A<true>::B x1(0);
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A<false>::B x2(0); // { dg-error "deduction|no match" }
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A<true>::B y1(0, '0');
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A<false>::B y2(0, '0'); // { dg-error "deduction|no match" }
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A<false>::B y3('0', 0);
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