[Bug c++/97580] New: reinterpret_cast<> and constant expression
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97580
Bug ID: 97580
Summary: reinterpret_cast<> and constant expression
Product: gcc
Version: 7.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: wolfgang.roe...@gi-de.com
Target Milestone: ---
Hi,
I would like to post a bug report for the GNU C/C++ compiler 7.5.0.
We use the compiler to generate code for a PowerPC processor.
Invokation line for the GNU C++ compiler:
ccppc -c -x c++ --std=gnu++17 -Wall -Werror -g -mcpu=e6500 -m32
-maltivec -mvrsave -ftls-model=local-exec -msdata=sysv
-fno-common -fno-openmp -mbig -mmultiple -mno-string -misel
-mstrict-align -fverbose-asm -G 8 -O3
-I
-D
X.CPP -oX.O
// file X.CPP
using T_PTR_FUNC = void (*)(int*);
void func1 (int*);
void func2 (float*);
constexpr T_PTR_FUNC arrFuncs[] =
{ func1, reinterpret_cast(func2) };
The compiler accepts this code even though a reinterpret_cast<> fails to be
a constant expression (cf. C++17 standard, 8.20/2).
With kind regards
W. Roehrl
[Bug c++/99001] New: indirect modification of function parameters
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99001
Bug ID: 99001
Summary: indirect modification of function parameters
Product: gcc
Version: 7.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: wolfgang.roe...@gi-de.com
Target Milestone: ---
Hi,
I would like to post a bug report for the GNU C/C++ compiler 7.5.0.
We use the compiler to generate code for a PowerPC processor.
Invokation line for the GNU C++ compiler:
ccppc -c -x c++ --std=gnu++17 -Wall -Werror -g -mcpu=e6500 -m32
-maltivec -mvrsave -ftls-model=local-exec -msdata=sysv
-fno-common -fno-openmp -mbig -mmultiple -mno-string -misel
-mstrict-align -fverbose-asm -G 8 -O3
-I
-D
X.CPP -oX.O
// file X.CPP
struct X
{
X (int& r) : rr(r) {}
~X () { rr = 0; }
int& rr;
};
int f1 (int i)
{
{ X x(i); }
return i;
}
int f2 (int i)
{
X x(i);
return i;
}
Wenn we compile this program the functions do the following:
- function f1() returns 0 - independently of the value of parameter i;
- function f2() returns the unmodified value of parameter i.
I think that the behaviour of f2() is wrong and f2() should behave as
function f1() does.
With kind regards
W. Roehrl
[Bug c++/100498] New: SFINAE and static inline function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100498
Bug ID: 100498
Summary: SFINAE and static inline function
Product: gcc
Version: 7.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: wolfgang.roe...@gi-de.com
Target Milestone: ---
Hi,
I would like to post a bug report for the GNU C/C++ compiler 7.5.0.
We use the compiler to generate code for a PowerPC processor.
Invokation line for the GNU C++ compiler:
ccppc -c -x c++ --std=gnu++17 -Wall -Werror -g -mcpu=e6500 -m32
-maltivec -mvrsave -ftls-model=local-exec -msdata=sysv
-fno-common -fno-openmp -mbig -mmultiple -mno-string -misel
-mstrict-align -fverbose-asm -G 8 -O3
-I
-D
X.CPP -oX.O
// file X.CPP
void f1 (int) {}
inline void f1 (float) {}
struct X
{
friend void f1 (int*) {}
};
void f1 (int*);
template
struct SFINAE
{ static constexpr F_* ptr = nullptr; };
template
struct SFINAE< F_, decltype((void)static_cast(f1), void()) >
{ static constexpr F_* ptr = f1; };
void func ()
{
using F1 = void(int);
constexpr F1* ptr1{ SFINAE::ptr };
static_assert (ptr1 != nullptr);
using F2 = void(float);
constexpr F2* ptr2{ SFINAE::ptr };
static_assert (ptr2 != nullptr);
using F3 = void(int*);
constexpr F3* ptr3{ SFINAE::ptr };
static_assert (ptr3 != nullptr);
}
Wenn we compile this program we get the following error messages:
x.CPP: In function 'void func()':
x.CPP:29:5: error: non-constant condition for static assertion
static_assert (ptr2 != nullptr);
^
x.CPP:29:25: error: '(f1 != 0)' is not a constant expression
static_assert (ptr2 != nullptr);
~^~
x.CPP:33:5: error: non-constant condition for static assertion
static_assert (ptr3 != nullptr);
^
x.CPP:33:25: error: '(f1 != 0)' is not a constant expression
static_assert (ptr3 != nullptr);
~^~
The reason for the first error messages is the inline attribute of function
"void f1 (float)"; the error messages disappear if "inline" is removed. I
I think this is not standard compliant.
A similar problem seems to arise with function "void f1 (int*)".
With kind regards
W. Roehrl
[Bug c++/100498] SFINAE and static inline function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100498 --- Comment #2 from Wolfgang Roehrl --- @Jonathan Wakely: Thank you very much for the detailled answer. Using this info it was possible for us to patch our 7.5 compiler version. At the moment we are constrained to use a 7.x compiler because we need support for the PowerPC e500 core. (To our knowledge this support has been phased out with the 8.x versions.)
