From 2eea00c518d5a72d0bdbc810ae675e7ad5fee414 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Fri, 27 Mar 2020 10:04:31 +0100 Subject: [PATCH] c++: Avoid calls in non-evaluated contexts affect whether function can or can't throw [PR94326] The following testcase FAILs -fcompare-debug, because if we emit a -Wreturn-local-addr warning, we tsubst decltype in order to print the warning and as that function could throw, set_flags_from_callee during that sets cp_function_chain->can_throw and later on we don't set TREE_NOTHROW on foo. While with -w or -Wno-return-local-addr, tsubst isn't called during the warning_at, cp_function_chain->can_throw is kept clear and TREE_NOTHROW is set on foo. It isn't just a matter of the warning though, in int foo (); int bar () { return sizeof (foo ()); } int baz () { return sizeof (int); } I don't really see why we should mark only baz as TREE_NOTHROW and not bar too, when neither can really throw. 2020-03-27 Jakub Jelinek PR c++/94326 * call.c (set_flags_from_callee): Don't update cp_function_chain->can_throw or current_function_returns_abnormally if cp_unevaluated_operand. * g++.dg/other/pr94326.C: New test. --- gcc/cp/ChangeLog | 5 +++++ gcc/cp/call.c | 11 +++++++---- gcc/testsuite/ChangeLog | 3 +++ gcc/testsuite/g++.dg/other/pr94326.C | 19 +++++++++++++++++++ 4 files changed, 34 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/other/pr94326.C diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 46208b2d756..5b8c5e329db 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,5 +1,10 @@ 2020-03-27 Jakub Jelinek + PR c++/94326 + * call.c (set_flags_from_callee): Don't update + cp_function_chain->can_throw or current_function_returns_abnormally + if cp_unevaluated_operand. + PR c++/94339 * cvt.c (ocp_convert): Handle COMPOUND_EXPR by recursion on the second operand and creating a new COMPOUND_EXPR if anything changed. diff --git a/gcc/cp/call.c b/gcc/cp/call.c index bae4b2c0f52..02220ffb3a1 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -333,11 +333,14 @@ set_flags_from_callee (tree call) && internal_fn_flags (CALL_EXPR_IFN (call)) & ECF_NOTHROW) nothrow = true; - if (!nothrow && at_function_scope_p () && cfun && cp_function_chain) - cp_function_chain->can_throw = 1; + if (cfun && cp_function_chain && !cp_unevaluated_operand) + { + if (!nothrow && at_function_scope_p ()) + cp_function_chain->can_throw = 1; - if (decl && TREE_THIS_VOLATILE (decl) && cfun && cp_function_chain) - current_function_returns_abnormally = 1; + if (decl && TREE_THIS_VOLATILE (decl)) + current_function_returns_abnormally = 1; + } TREE_NOTHROW (call) = nothrow; } diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index f0b1b5f006b..5f9b164d486 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,5 +1,8 @@ 2020-03-27 Jakub Jelinek + PR c++/94326 + * g++.dg/other/pr94326.C: New test. + PR c++/94339 * g++.dg/other/pr94339.C: New test. * g++.dg/ext/attr-copy-2.C: Comment out failing tests due to PR94346. diff --git a/gcc/testsuite/g++.dg/other/pr94326.C b/gcc/testsuite/g++.dg/other/pr94326.C new file mode 100644 index 00000000000..4069c038d52 --- /dev/null +++ b/gcc/testsuite/g++.dg/other/pr94326.C @@ -0,0 +1,19 @@ +// PR c++/94326 +// { dg-do compile { target c++11 } } +// { dg-options "-fcompare-debug" } + +template struct A { + const int &foo() { return 0; } // { dg-warning "returning reference to temporary" } + template void bar(_Kt) { foo(); } +}; +struct B { + A<> b; + template auto baz(_Kt p1) -> decltype(b.bar(p1)) { + b.bar(p1); + } +}; +struct C {}; +void operator<(C, int) { + B a; + a.baz(C{}); +} -- 2.30.2