From 3774c0b934c4fe13c2d527b757002bdea09f7039 Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Wed, 5 Feb 2020 01:02:22 -0500 Subject: [PATCH] cgraph: A COMDAT decl always has non-zero address. We should be able to assume that a template instantiation or other COMDAT has non-zero address even if MAKE_DECL_ONE_ONLY for the target sets DECL_WEAK and we haven't yet decided to emit a definition in this translation unit. PR c++/92003 * symtab.c (symtab_node::nonzero_address): A DECL_COMDAT decl has non-zero address even if weak and not yet defined. --- gcc/ChangeLog | 6 ++++++ gcc/symtab.c | 10 +++++----- gcc/testsuite/g++.dg/cpp0x/constexpr-static13.C | 17 +++++++++++++++++ 3 files changed, 28 insertions(+), 5 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-static13.C diff --git a/gcc/ChangeLog b/gcc/ChangeLog index b8fa14e00b6..c31b861fff8 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2020-02-05 Jason Merrill + + PR c++/92003 + * symtab.c (symtab_node::nonzero_address): A DECL_COMDAT decl has + non-zero address even if weak and not yet defined. + 2020-02-05 Martin Sebor PR tree-optimization/92765 diff --git a/gcc/symtab.c b/gcc/symtab.c index eae891ab211..a879c095a1a 100644 --- a/gcc/symtab.c +++ b/gcc/symtab.c @@ -2058,22 +2058,22 @@ symtab_node::nonzero_address () bind to NULL. This is on by default on embedded targets only. Otherwise all non-WEAK symbols must be defined and thus non-NULL or - linking fails. Important case of WEAK we want to do well are comdats. - Those are handled by later check for definition. + linking fails. Important case of WEAK we want to do well are comdats, + which also must be defined somewhere. When parsing, beware the cases when WEAK attribute is added later. */ - if (!DECL_WEAK (decl) + if ((!DECL_WEAK (decl) || DECL_COMDAT (decl)) && flag_delete_null_pointer_checks) { refuse_visibility_changes = true; return true; } - /* If target is defined and either comdat or not extern, we know it will be + /* If target is defined and not extern, we know it will be output and thus it will bind to non-NULL. Play safe for flag_delete_null_pointer_checks where weak definition may be re-defined by NULL. */ - if (definition && (!DECL_EXTERNAL (decl) || DECL_COMDAT (decl)) + if (definition && !DECL_EXTERNAL (decl) && (flag_delete_null_pointer_checks || !DECL_WEAK (decl))) { if (!DECL_WEAK (decl)) diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-static13.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-static13.C new file mode 100644 index 00000000000..644f9f7f893 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-static13.C @@ -0,0 +1,17 @@ +// PR c++/92003 +// { dg-do compile { target c++11 } } +// { dg-prune-output "narrowing conversion" } + +constexpr char const* get_c_str() { return "abc"; } +constexpr bool use_get_c_str_in_constexpr_context{get_c_str()}; // works + +template +struct string { + static constexpr char const* c_str() { return c; } + + private: + static constexpr char c[]{Cs..., '\0'}; +}; + +constexpr char const* cstr{string<'a', 'b', 'c'>::c_str()}; +constexpr bool use_cstr_in_constexpr_context{cstr}; // doesn't work -- 2.30.2