From 74051031aaae0833759d30e3519bcea03f41f2e0 Mon Sep 17 00:00:00 2001 From: jason Date: Mon, 19 Dec 2011 05:57:52 +0000 Subject: [PATCH] PR c++/51489 * semantics.c (cxx_eval_outermost_constant_expr): Check for conversion from pointer to integer here. (cxx_eval_constant_expression) [NOP_EXPR]: Not here. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@182470 138bc75d-0d04-0410-961f-82ee72b054a4 --- gcc/cp/ChangeLog | 7 +++++ gcc/cp/semantics.c | 44 ++++++++++----------------- gcc/testsuite/ChangeLog | 5 +++ gcc/testsuite/g++.dg/cpp0x/constexpr-ptrsub.C | 14 +++++++++ 4 files changed, 42 insertions(+), 28 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-ptrsub.C diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 7d625eed554..6f1bc26c9a9 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,10 @@ +2011-12-19 Jason Merrill + + PR c++/51489 + * semantics.c (cxx_eval_outermost_constant_expr): Check for + conversion from pointer to integer here. + (cxx_eval_constant_expression) [NOP_EXPR]: Not here. + 2011-12-18 Paolo Carlini * semantics.c (finish_compound_literal): Don't call check_narrowing diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c index 76b0b18bd69..e73b40a0e4f 100644 --- a/gcc/cp/semantics.c +++ b/gcc/cp/semantics.c @@ -7704,17 +7704,6 @@ cxx_eval_constant_expression (const constexpr_call *call, tree t, tree oldop = TREE_OPERAND (t, 0); tree op = oldop; tree to = TREE_TYPE (t); - tree source = TREE_TYPE (op); - if (TYPE_PTR_P (source) && ARITHMETIC_TYPE_P (to) - && !(TREE_CODE (op) == COMPONENT_REF - && TYPE_PTRMEMFUNC_P (TREE_TYPE (TREE_OPERAND (op, 0))))) - { - if (!allow_non_constant) - error ("conversion of expression %qE of pointer type " - "cannot yield a constant expression", op); - *non_constant_p = true; - return t; - } op = cxx_eval_constant_expression (call, TREE_OPERAND (t, 0), allow_non_constant, addr, non_constant_p); @@ -7803,6 +7792,20 @@ cxx_eval_outermost_constant_expr (tree t, bool allow_non_constant) non_constant_p = true; } + /* Technically we should check this for all subexpressions, but that + runs into problems with our internal representation of pointer + subtraction and the 5.19 rules are still in flux. */ + if (CONVERT_EXPR_CODE_P (TREE_CODE (r)) + && ARITHMETIC_TYPE_P (TREE_TYPE (r)) + && TREE_CODE (TREE_OPERAND (r, 0)) == ADDR_EXPR) + { + if (!allow_non_constant) + error ("conversion from pointer type %qT " + "to arithmetic type %qT in a constant-expression", + TREE_TYPE (TREE_OPERAND (r, 0)), TREE_TYPE (r)); + non_constant_p = true; + } + if (non_constant_p && !allow_non_constant) return error_mark_node; else if (non_constant_p && TREE_CONSTANT (t)) @@ -8110,25 +8113,10 @@ potential_constant_expression_1 (tree t, bool want_rval, tsubst_flags_t flags) case NOP_EXPR: case CONVERT_EXPR: case VIEW_CONVERT_EXPR: - /* -- an array-to-pointer conversion that is applied to an lvalue - that designates an object with thread or automatic storage - duration; FIXME not implemented as it breaks constexpr arrays; - need to fix the standard - -- a type conversion from a pointer or pointer-to-member type - to a literal type. */ + /* -- a reinterpret_cast. FIXME not implemented, and this rule + may change to something more specific to type-punning (DR 1312). */ { tree from = TREE_OPERAND (t, 0); - tree source = TREE_TYPE (from); - tree target = TREE_TYPE (t); - if (TYPE_PTR_P (source) && ARITHMETIC_TYPE_P (target) - && !(TREE_CODE (from) == COMPONENT_REF - && TYPE_PTRMEMFUNC_P (TREE_TYPE (TREE_OPERAND (from, 0))))) - { - if (flags & tf_error) - error ("conversion of expression %qE of pointer type " - "cannot yield a constant expression", from); - return false; - } return (potential_constant_expression_1 (from, TREE_CODE (t) != VIEW_CONVERT_EXPR, flags)); } diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 9562a9da52b..dc77cbec441 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2011-12-19 Jason Merrill + + PR c++/51489 + * g++.dg/cpp0x/constexpr-ptrsub.C: New. + 2011-12-18 Hans-Peter Nilsson * gcc.dg/pr51491-2.c: Fix "cleanup-treee-dump" typo. diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-ptrsub.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-ptrsub.C new file mode 100644 index 00000000000..bccec73bb0b --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-ptrsub.C @@ -0,0 +1,14 @@ +// PR c++/51489 +// DR 1313 +// { dg-options "-std=c++0x" } + +struct array +{ + constexpr array() :x(0) {} + constexpr int const* begin() { return &x; } + int x; +}; +constexpr array aa; +constexpr auto b = aa.begin(); +static_assert(b-b == 0, "compiles just fine"); +static_assert(aa.begin()-aa.begin() == 0, "compiler thinks it's not a constant expression"); -- 2.11.0