[Bug c/60837] New: initializer element is not constant: int test = (1, 2) + 1;
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60837
Bug ID: 60837
Summary: initializer element is not constant: int test = (1, 2)
+ 1;
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: potrepa...@asc-ural.ru
main.c
--
int test = (6, 9) + 1;
int main( void ) { return 0; }
--
>gcc main.c
main.c:1:1: error: initializer element is not constant
[Bug c/60837] initializer element is not constant: int test = (1, 2) + 1;
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60837 ilya changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #1 from ilya --- Reread C standart. 6.6 Constant expressions Constraints Constant expressions shall not contain assignment, increment, decrement, function-call, or comma operators, except when they are contained within a subexpression that is not evaluated.
[Bug c/60838] New: bugos warning: initializer element is not a constant expression: int test = (0 ? (1,0) : 0) + 1;
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60838
Bug ID: 60838
Summary: bugos warning: initializer element is not a constant
expression: int test = (0 ? (1,0) : 0) + 1;
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: potrepa...@asc-ural.ru
main.c:
-
int test = (0 ? (3, 0) : 0) + 1;
int main( void ) { return 0; }
-
>gcc main.c
main.c:1:12: warning: initializer element is not a constant expression
This is work, but generate warning:
#define CT_ASSERT_EXPR(ex) (0 ? ((struct { int a:((ex) ? 1 : -1); } *)0,0) :
0)
#define CT_ASSERT(ex) extern char ct_assert_[ CT_ASSERT_EXPR(ex)+1 ]
warning: variably modified 'ct_assert_' at file scope
According C standart:
6.6 Constant expressions
Constant expressions shall not contain assignment, increment, decrement,
function-call, or comma operators, except when they are contained within a
subexpression that is not evaluated.
6.5.15 Conditional operator
The first operand is evaluated; there is a sequence point after its evaluation.
The second operand is evaluated only if the first compares unequal to 0; the
third operand is evaluated only if the first compares equal to 0; the result is
the value of the second or third operand (whichever is evaluated), converted to
the type described below.
[Bug c/60838] bugos warning: initializer element is not a constant expression: int test = (0 ? (1,0) : 0) + 1;
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60838
--- Comment #1 from ilya ---
Another testcase:
main.c
-
int test1 = (0 ? 0 : 0) + 1;
int test2 = (0 ? (3, 0) : 0) + 1;
int test3[(0 ? 0 : 0) + 1];
int test4[(0 ? (3, 0) : 0) + 1];
int main( void ) { return 0; }
-
>gcc main.c
main.c:2:13: warning: initializer element is not a constant expression
main.c:4:5: error: variably modified ‘test4’ at file scope
Checked for:
gcc version 4.5.3 (GCC)
gcc version 4.7.3
[Bug c/63991] New: redundant read when write to volatile member of packed structure
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63991
Bug ID: 63991
Summary: redundant read when write to volatile member of packed
structure
Product: gcc
Version: 4.8.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: potrepa...@asc-ural.ru
There is redundant read when write to volatile member of packed structure:
exti.c:
---
typedef struct
{
volatile unsigned int IMR;
volatile unsigned int EMR;
volatile unsigned int RTSR;
volatile unsigned int FTSR;
volatile unsigned int SWIER;
volatile unsigned int PR;
} EXTI_TypeDef;
void
EXTI_5_IRQHandler( EXTI_TypeDef * exti ) { exti->PR = 1 << 5; }
---
make.bat:
---
arm-none-eabi-gcc -mthumb -march=armv7e-m -fpack-struct -O2 -c exti.c -o
exti-bug.o
arm-none-eabi-gcc -mthumb -march=armv7e-m -O2 -c exti.c -o exti.o
arm-none-eabi-objdump -a -S exti.o > exti.lst
arm-none-eabi-objdump -a -S exti-bug.o > exti-bug.lst
---
exti.lst
---
exti.o: file format elf32-littlearm
exti.o
Disassembly of section .text:
:
0:2320 movsr3, #32
2:6143 strr3, [r0, #20]
4:4770 bxlr
6:bf00 nop
exti-bug.lst
exti-bug.o: file format elf32-littlearm
exti-bug.o
Disassembly of section .text:
:
0:2320 movsr3, #32
2:6942 ldrr2, [r0, #20]
4:6143 strr3, [r0, #20]
6:4770 bxlr
