[Bug c/60083] Duplicate conversion warnings from negative integer to unsigned type (gcc-4.3 emits only one warning)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60083 Manuel López-Ibáñez changed: What|Removed |Added Status|NEW |RESOLVED CC||manu at gcc dot gnu.org Resolution|--- |FIXED --- Comment #5 from Manuel López-Ibáñez --- This probably got fixed when early folding was fixed: gcc 8.0 -Wsign-conversion -Wparentheses -Wall -Wextra -Wconversion gives: :3:48: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses] unsigned short s = ~0x4578ADBCAA1DE677LL ^ a == 0; ~~^~~~ :3:44: warning: unsigned conversion from 'long long int' to 'short unsigned int' changes value from '-5005942011641849463' to '6537' [-Woverflow] unsigned short s = ~0x4578ADBCAA1DE677LL ^ a == 0; ~~^~~~ The fix-it notes for -Wparentheses and having some warnings enabled by default would be nice, but they are a different topic altogether.
[Bug c/60083] Duplicate conversion warnings from negative integer to unsigned type (gcc-4.3 emits only one warning)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60083 Martin Sebor changed: What|Removed |Added CC||msebor at gcc dot gnu.org --- Comment #4 from Martin Sebor --- It's useful to compare GCC output to Clang's (with no options): t.c:3:44: warning: ^ has lower precedence than ==; == will be evaluated first [-Wparentheses] unsigned short s = ~0x4578ADBCAA1DE677LL ^ a == 0; ^~~~ t.c:3:44: note: place parentheses around the '==' expression to silence this warning unsigned short s = ~0x4578ADBCAA1DE677LL ^ a == 0; ^ ( ) t.c:3:44: note: place parentheses around the ^ expression to evaluate it first unsigned short s = ~0x4578ADBCAA1DE677LL ^ a == 0; ^ () t.c:3:44: warning: implicit conversion from 'long long' to 'unsigned short' changes value from -5005942011641849463 to 6537 [-Wconstant-conversion] unsigned short s = ~0x4578ADBCAA1DE677LL ^ a == 0; ~ ~~^~~~ 2 warnings generated.
[Bug c/60083] Duplicate conversion warnings from negative integer to unsigned type (gcc-4.3 emits only one warning)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60083 --- Comment #3 from Marek Polacek --- Started with r139049.
[Bug c/60083] Duplicate conversion warnings from negative integer to unsigned type (gcc-4.3 emits only one warning)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60083
--- Comment #1 from Chengnian Sun chengniansun at gmail dot com ---
I think the following case is similar to the reported case. The only difference
is the message content. The following case also triggers gcc -O0 to emit two
duplicate warnings. But gcc -O1 emits only one warning.
$: cat s.c
extern short fn2(short, short);
unsigned long g;
void fn1() {
int const l = 0;
fn2(((g = l != 0) 10LL) | 91608LL, 0);
}
$: gcc-trunk -c -Wconversion -std=c99 s.c
s.c: In function ‘fn1’:
s.c:5:7: warning: conversion to ‘short int’ alters ‘long long int’ constant
value [-Wconversion]
fn2(((g = l != 0) 10LL) | 91608LL, 0);
^
s.c:5:7: warning: conversion to ‘short int’ alters ‘long long int’ constant
value [-Wconversion]
$: gcc-trunk -c -Wconversion -std=c99 s.c -O1
s.c: In function ‘fn1’:
s.c:5:7: warning: conversion to ‘short int’ from ‘long long int’ may alter its
value [-Wconversion]
fn2(((g = l != 0) 10LL) | 91608LL, 0);
^
$:
[Bug c/60083] Duplicate conversion warnings from negative integer to unsigned type (gcc-4.3 emits only one warning)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60083 Marek Polacek mpolacek at gcc dot gnu.org changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2014-02-07 CC||mpolacek at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #2 from Marek Polacek mpolacek at gcc dot gnu.org --- Yeah, I bet we'll have tons of those ;/.
