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PR c++/91705 - constexpr evaluation rejects ++/-- on floats.

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* constexpr.c (cxx_eval_increment_expression): Call fold_simple on
	the offset.

	* g++.dg/cpp1y/constexpr-incr2.C: New test.

From-SVN: r275613
This commit is contained in:
Marek Polacek 2019-09-10 21:04:33 +00:00 committed by Marek Polacek
parent efc864927f
commit d85569f63d
4 changed files with 81 additions and 0 deletions
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6
gcc/cp/ChangeLog
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@ -1,3 +1,9 @@
2019-09-10 Marek Polacek <polacek@redhat.com>
PR c++/91705 - constexpr evaluation rejects ++/-- on floats.
* constexpr.c (cxx_eval_increment_expression): Call fold_simple on
the offset.
2019-09-10 Paolo Carlini <paolo.carlini@oracle.com>
* decl.c (has_designator_problem): Use cp_expr_loc_or_input_loc

4
gcc/cp/constexpr.c
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@ -4164,6 +4164,10 @@ cxx_eval_increment_expression (const constexpr_ctx *ctx, tree t,
tree offset = TREE_OPERAND (t, 1);
gcc_assert (TREE_CONSTANT (offset));
/* OFFSET is constant, but perhaps not constant enough. We need to
e.g. bash FLOAT_EXPRs to REAL_CSTs. */
offset = fold_simple (offset);
/* The operand as an lvalue. */
op = cxx_eval_constant_expression (ctx, op, true,
non_constant_p, overflow_p);

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2019-09-10 Marek Polacek <polacek@redhat.com>
PR c++/91705 - constexpr evaluation rejects ++/-- on floats.
* g++.dg/cpp1y/constexpr-incr2.C: New test.
2019-09-10 David Edelsohn <dje.gcc@gmail.com>
* gfortran.dg/default_format_1.f90: Remove XFAIL AIX.

66
gcc/testsuite/g++.dg/cpp1y/constexpr-incr2.C Normal file
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@ -0,0 +1,66 @@
// PR c++/91705 - constexpr evaluation rejects ++/-- on floats.
// { dg-do compile { target c++14 } }
#define SA(X) static_assert((X),#X)
template <class T>
constexpr T fn1(T t)
{
return ++t;
}
constexpr float fn2(float t)
{
return ++t;
}
template <class T>
constexpr T fn3(T t)
{
return --t;
}
constexpr float fn4(float t)
{
return --t;
}
template <class T>
constexpr T fn5(T t)
{
return t++;
}
constexpr float fn6(float t)
{
return t++;
}
template <class T>
constexpr T fn7(T t)
{
return t--;
}
constexpr float fn8(float t)
{
return t--;
}
constexpr double r1 = fn1(2.0f);
SA(r1 == 3);
constexpr double r2 = fn2(2.0f);
SA(r2 == 3);
constexpr double r3 = fn3(2.0f);
SA(r3 == 1);
constexpr double r4 = fn4(2.0f);
SA(r4 == 1);
constexpr double r5 = fn5(2.0f);
SA(r5 == 2);
constexpr double r6 = fn6(2.0f);
SA(r6 == 2);
constexpr double r7 = fn7(2.0f);
SA(r7 == 2);
constexpr double r8 = fn8(2.0f);
SA(r8 == 2);