From d950b005f993d092dd6e0cefbaf1ecfaf6765cb4 Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Tue, 12 Feb 2019 16:18:51 -0500 Subject: [PATCH] PR c++/89144 - link error with constexpr initializer_list. In this PR, we were unnecessarily rejecting a constexpr initializer_list with no elements. This seems like a fairly useless degenerate case, but it makes sense to avoid allocating an underlying array at all if there are no elements and instead use a null pointer, like the initializer_list default constructor. If the (automatic storage duration) list does have initializer elements, we continue to reject the declaration, because the initializer_list ends up referring to an automatic storage duration temporary array, which is not a suitable constant initializer. If we make it static, it should be OK because we refer to a static array. The second hunk fixes that case. It also means we won't diagnose some real errors in templates, but those diagnostics aren't required, and we'll get them when the template is instantiated. * call.c (convert_like_real) [ck_list]: Don't allocate a temporary array for an empty list. * typeck2.c (store_init_value): Don't use cxx_constant_init in a template. From-SVN: r268827 --- gcc/cp/ChangeLog | 8 +++ gcc/cp/call.c | 61 +++++++++++-------- gcc/cp/typeck2.c | 5 ++ .../g++.dg/cpp0x/constexpr-initlist11.C | 11 ++++ .../g++.dg/cpp0x/constexpr-initlist11a.C | 10 +++ 5 files changed, 69 insertions(+), 26 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-initlist11.C create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-initlist11a.C diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 5fe18ccdab6..cb747615716 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,11 @@ +2019-02-12 Jason Merrill + + PR c++/89144 - link error with constexpr initializer_list. + * call.c (convert_like_real) [ck_list]: Don't allocate a temporary + array for an empty list. + * typeck2.c (store_init_value): Don't use cxx_constant_init in a + template. + 2019-02-11 Jason Merrill PR c++/89241 - ICE with __func__ in lambda in template. diff --git a/gcc/cp/call.c b/gcc/cp/call.c index e9c131dd66b..c53eb582aac 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -7085,34 +7085,42 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum, { /* Conversion to std::initializer_list. */ tree elttype = TREE_VEC_ELT (CLASSTYPE_TI_ARGS (totype), 0); - tree new_ctor = build_constructor (init_list_type_node, NULL); unsigned len = CONSTRUCTOR_NELTS (expr); - tree array, val, field; - vec *vec = NULL; - unsigned ix; + tree array; - /* Convert all the elements. */ - FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (expr), ix, val) + if (len) { - tree sub = convert_like_real (convs->u.list[ix], val, fn, argnum, - false, false, complain); - if (sub == error_mark_node) - return sub; - if (!BRACE_ENCLOSED_INITIALIZER_P (val) - && !check_narrowing (TREE_TYPE (sub), val, complain)) - return error_mark_node; - CONSTRUCTOR_APPEND_ELT (CONSTRUCTOR_ELTS (new_ctor), NULL_TREE, sub); - if (!TREE_CONSTANT (sub)) - TREE_CONSTANT (new_ctor) = false; + tree val; unsigned ix; + + tree new_ctor = build_constructor (init_list_type_node, NULL); + + /* Convert all the elements. */ + FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (expr), ix, val) + { + tree sub = convert_like_real (convs->u.list[ix], val, fn, + argnum, false, false, complain); + if (sub == error_mark_node) + return sub; + if (!BRACE_ENCLOSED_INITIALIZER_P (val) + && !check_narrowing (TREE_TYPE (sub), val, complain)) + return error_mark_node; + CONSTRUCTOR_APPEND_ELT (CONSTRUCTOR_ELTS (new_ctor), + NULL_TREE, sub); + if (!TREE_CONSTANT (sub)) + TREE_CONSTANT (new_ctor) = false; + } + /* Build up the array. */ + elttype = cp_build_qualified_type + (elttype, cp_type_quals (elttype) | TYPE_QUAL_CONST); + array = build_array_of_n_type (elttype, len); + array = finish_compound_literal (array, new_ctor, complain); + /* Take the address explicitly rather than via decay_conversion + to avoid the error about taking the address of a temporary. */ + array = cp_build_addr_expr (array, complain); } - /* Build up the array. */ - elttype = cp_build_qualified_type - (elttype, cp_type_quals (elttype) | TYPE_QUAL_CONST); - array = build_array_of_n_type (elttype, len); - array = finish_compound_literal (array, new_ctor, complain); - /* Take the address explicitly rather than via decay_conversion - to avoid the error about taking the address of a temporary. */ - array = cp_build_addr_expr (array, complain); + else + array = nullptr_node; + array = cp_convert (build_pointer_type (elttype), array, complain); if (array == error_mark_node) return error_mark_node; @@ -7123,11 +7131,12 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum, totype = complete_type_or_maybe_complain (totype, NULL_TREE, complain); if (!totype) return error_mark_node; - field = next_initializable_field (TYPE_FIELDS (totype)); + tree field = next_initializable_field (TYPE_FIELDS (totype)); + vec *vec = NULL; CONSTRUCTOR_APPEND_ELT (vec, field, array); field = next_initializable_field (DECL_CHAIN (field)); CONSTRUCTOR_APPEND_ELT (vec, field, size_int (len)); - new_ctor = build_constructor (totype, vec); + tree new_ctor = build_constructor (totype, vec); return get_target_expr_sfinae (new_ctor, complain); } diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c index 05998a3dc17..ac2c253196b 100644 --- a/gcc/cp/typeck2.c +++ b/gcc/cp/typeck2.c @@ -850,6 +850,11 @@ store_init_value (tree decl, tree init, vec** cleanups, int flags) non-inline in-class-initialized static data member. */ if (!require_constant_expression (value)) value = error_mark_node; + else if (processing_template_decl) + /* In a template we might not have done the necessary + transformations to make value actually constant, + e.g. extend_ref_init_temps. */ + value = maybe_constant_init (value, decl, true); else value = cxx_constant_init (value, decl); } diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-initlist11.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-initlist11.C new file mode 100644 index 00000000000..da5eab241de --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-initlist11.C @@ -0,0 +1,11 @@ +// PR c++/89144 +// { dg-do link { target c++11 } } + +#include + +template void b() { + static constexpr std::initializer_list c{ 42 }; + constexpr std::initializer_list l { }; +} + +int main() { b(); } diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-initlist11a.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-initlist11a.C new file mode 100644 index 00000000000..2597c3836ed --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-initlist11a.C @@ -0,0 +1,10 @@ +// PR c++/89144 +// { dg-do link { target c++11 } } + +#include + +template void b() { + constexpr std::initializer_list l { 42 }; // { dg-error "" } +} + +int main() { b(); } -- 2.30.2