http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49120
Summary: bogus "value computed is not used" warning (variable-length array in compound statement) Product: gcc Version: 4.5.1 Status: UNCONFIRMED Severity: minor Priority: P3 Component: c AssignedTo: unassig...@gcc.gnu.org ReportedBy: kari.nurm...@stonesoft.com When declaring a variable-length array in the beginning of a compound statement, so that the length expression contains at least one operator, the warning "value computed is not used" is incorrectly given for the computed length of the array (with -Wall). For example: ~$ cat kok1.c int main(void) { int foo = 1; ({ char bar[foo + 1]; /* <==== */ bar[0] = 0; }); return 0; } ~$ gcc-4.5 -Wall kok1.c -o kok1 kok1.c: In function ‘main’: kok1.c:5:22: warning: value computed is not used ~$ gcc-4.5 --version gcc-4.5 (Ubuntu/Linaro 4.5.1-7ubuntu2) 4.5.1 ... If the compound statement is replaced with a block in this example, the warning goes away: ~$ cat kok2.c int main(void) { int foo = 1; { char bar[foo + 1]; bar[0] = 0; } return 0; } ~$ gcc-4.5 -Wall kok2.c -o kok2 ~$ In gcc 4.4 the bogus warning does not appear: ~$ gcc-4.4 -Wall kok1.c -o kok1 ~$ gcc-4.4 --version gcc-4.4 (Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5 ...