From d419e176d74162af6513be0b3bc1031726543993 Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Fri, 17 Apr 2020 15:47:15 -0400 Subject: [PATCH] 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. --- gcc/cp/ChangeLog | 9 +++++++++ gcc/cp/constexpr.c | 8 ++++++-- gcc/testsuite/ChangeLog | 6 ++++++ gcc/testsuite/g++.dg/cpp2a/nontype-class34.C | 16 ++++++++++++++++ gcc/testsuite/g++.dg/cpp2a/nontype-class35.C | 17 +++++++++++++++++ 5 files changed, 54 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp2a/nontype-class34.C create mode 100644 gcc/testsuite/g++.dg/cpp2a/nontype-class35.C diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 797984b..53daab1 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,12 @@ +2020-04-17 Marek Polacek + + 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. + 2020-04-20 Patrick Palka PR c++/94628 diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index c8e7d08..6b3e514 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -6534,6 +6534,12 @@ cxx_eval_outermost_constant_expr (tree t, bool allow_non_constant, bool non_constant_p = false; bool overflow_p = false; + if (BRACE_ENCLOSED_INITIALIZER_P (t)) + { + gcc_checking_assert (allow_non_constant); + return t; + } + constexpr_global_ctx global_ctx; constexpr_ctx ctx = { &global_ctx, NULL, NULL, NULL, NULL, NULL, NULL, allow_non_constant, strict, @@ -8295,7 +8301,6 @@ bool is_nondependent_constant_expression (tree t) { return (!type_unknown_p (t) - && !BRACE_ENCLOSED_INITIALIZER_P (t) && is_constant_expression (t) && !instantiation_dependent_expression_p (t)); } @@ -8307,7 +8312,6 @@ bool is_nondependent_static_init_expression (tree t) { return (!type_unknown_p (t) - && !BRACE_ENCLOSED_INITIALIZER_P (t) && is_static_init_expression (t) && !instantiation_dependent_expression_p (t)); } diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 813f94c..e733cae 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2020-04-17 Marek Polacek + + PR c++/94592 + * g++.dg/cpp2a/nontype-class34.C: New test. + * g++.dg/cpp2a/nontype-class35.C: New test. + 2020-04-20 Patrick Palka PR c++/94628 diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class34.C b/gcc/testsuite/g++.dg/cpp2a/nontype-class34.C new file mode 100644 index 0000000..2d3ba01 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class34.C @@ -0,0 +1,16 @@ +// PR c++/94592 - ICE with { } as template argument. +// { dg-do compile { target c++2a } } + +struct A { + constexpr A() {} +}; + +template struct B { }; + +template void bar () { + B<{}> var; +} + +void fu() { + bar(); +} diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class35.C b/gcc/testsuite/g++.dg/cpp2a/nontype-class35.C new file mode 100644 index 0000000..78cf0a3 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class35.C @@ -0,0 +1,17 @@ +// PR c++/94592 - ICE with { } as template argument. +// { dg-do compile { target c++2a } } + +struct A { + int i; + constexpr A(int n) : i(n) {} +}; + +template struct B { int i; constexpr B() : i(a.i) { } }; + +template void bar () { + B<{1}> var; +} + +void fu() { + bar(); +} -- 2.7.4