From 69bf1c7d5ee21392334f1982d1b40c38e103bbd4 Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Tue, 1 Dec 2020 10:39:08 -0500 Subject: [PATCH] c++: Fix ICE with inline variable in template [PR97975] In this test, we have static inline const int c = b; in a class template, and we call store_init_value as usual. There, the value is IMPLICIT_CONV_EXPR(b) which is is_nondependent_static_init_expression but isn't is_nondependent_constant_expression (they only differ in STRICT). We call fold_non_dependent_expr, but that just returns the expression because it only instantiates is_nondependent_constant_expression expressions. Since we're not checking the initializer of a constexpr variable, we go on to call maybe_constant_init, whereupon we crash because it tries to evaluate all is_nondependent_static_init_expression expressions, which our value is, but it still contains a template code. I think the fix is to call fold_non_dependent_init instead of maybe_constant_init, and only call fold_non_dependent_expr on the "this is a constexpr variable" path so as to avoid instantiating twice in a row. Outside a template this should also avoid evaluating the value twice. gcc/cp/ChangeLog: PR c++/97975 * constexpr.c (fold_non_dependent_init): Add a tree parameter. Use it. * cp-tree.h (fold_non_dependent_init): Add a tree parameter with a default value. * typeck2.c (store_init_value): Call fold_non_dependent_expr only when checking the initializer for constexpr variables. Call fold_non_dependent_init instead of maybe_constant_init. gcc/testsuite/ChangeLog: PR c++/97975 * g++.dg/cpp1z/inline-var8.C: New test. --- gcc/cp/constexpr.c | 7 ++++--- gcc/cp/cp-tree.h | 2 +- gcc/cp/typeck2.c | 7 +++++-- gcc/testsuite/g++.dg/cpp1z/inline-var8.C | 17 +++++++++++++++++ 4 files changed, 27 insertions(+), 6 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp1z/inline-var8.C diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index 054ee52..9a1a1db 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -7271,7 +7271,8 @@ maybe_fold_non_dependent_expr (tree expr, tree fold_non_dependent_init (tree t, tsubst_flags_t complain /*=tf_warning_or_error*/, - bool manifestly_const_eval /*=false*/) + bool manifestly_const_eval /*=false*/, + tree object /* = NULL_TREE */) { if (t == NULL_TREE) return NULL_TREE; @@ -7279,7 +7280,7 @@ fold_non_dependent_init (tree t, if (processing_template_decl) { t = fold_non_dependent_expr_template (t, complain, - manifestly_const_eval, NULL_TREE); + manifestly_const_eval, object); /* maybe_constant_init does this stripping, so do it here too. */ if (TREE_CODE (t) == TARGET_EXPR) { @@ -7290,7 +7291,7 @@ fold_non_dependent_init (tree t, return t; } - return maybe_constant_init (t, NULL_TREE, manifestly_const_eval); + return maybe_constant_init (t, object, manifestly_const_eval); } /* Like maybe_constant_value, but returns a CONSTRUCTOR directly, rather diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 3b67e7a..41ae13b 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -8014,7 +8014,7 @@ extern tree maybe_fold_non_dependent_expr (tree, tsubst_flags_t = tf_warning_or_error); extern tree fold_non_dependent_init (tree, tsubst_flags_t = tf_warning_or_error, - bool = false); + bool = false, tree = NULL_TREE); extern tree fold_simple (tree); extern bool reduced_constant_expression_p (tree); extern bool is_instantiation_of_constexpr (tree); diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c index 721987e..575c609 100644 --- a/gcc/cp/typeck2.c +++ b/gcc/cp/typeck2.c @@ -744,11 +744,13 @@ store_init_value (tree decl, tree init, vec** cleanups, int flags) { bool const_init; tree oldval = value; - value = fold_non_dependent_expr (value, tf_warning_or_error, true, decl); if (DECL_DECLARED_CONSTEXPR_P (decl) || (DECL_IN_AGGR_P (decl) && DECL_INITIALIZED_IN_CLASS_P (decl))) { + value = fold_non_dependent_expr (value, tf_warning_or_error, + /*manifestly_const_eval=*/true, + decl); /* Diagnose a non-constant initializer for constexpr variable or non-inline in-class-initialized static data member. */ if (!require_constant_expression (value)) @@ -762,7 +764,8 @@ store_init_value (tree decl, tree init, vec** cleanups, int flags) value = cxx_constant_init (value, decl); } else - value = maybe_constant_init (value, decl, true); + value = fold_non_dependent_init (value, tf_warning_or_error, + /*manifestly_const_eval=*/true, decl); if (TREE_CODE (value) == CONSTRUCTOR && cp_has_mutable_p (type)) /* Poison this CONSTRUCTOR so it can't be copied to another constexpr variable. */ diff --git a/gcc/testsuite/g++.dg/cpp1z/inline-var8.C b/gcc/testsuite/g++.dg/cpp1z/inline-var8.C new file mode 100644 index 0000000..8db3c19 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1z/inline-var8.C @@ -0,0 +1,17 @@ +// PR c++/97975 +// { dg-do compile { target c++17 } } + +template +class A +{ + static const float b; + static inline const int c = b; +}; + +A a; + +struct B +{ + static const float b; + static inline const int c = b; +}; -- 2.7.4