https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115185
Bug ID: 115185
Summary: Missing "too long" warning when string-array size
doesn't include NULL byte
Product: gcc
Version: 14.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: Hi-Angel at yandex dot ru
Target Milestone: ---
It's a common pattern to have some `enum Foo { one, two, three }`, and then
some 2-dimensinal array `FooAsString`, which allows one to get name of the
`Foo` field by passing an index, like `printf("%s",
FooAsString[my_Foo_variable])`.
Problem though is that it isn't allowed to declare multi-dimensinal array and
omit all dimensions, so one have to declare as `FooAsString[][6]` for example.
That makes programmer to rely on the compiler to detect when the `6` is not
enough to hold the string.
GCC kind of tries to warn about that, however its check is off-by-one because
it does not take into account the NULL byte that the C-string has to end with.
# Steps to reproduce (in terms of terminal commands)
λ cat test.c
#include <stdio.h>
int main() {
enum Foo {
hello,
} obj = hello;
static const char description[][5] = {[hello] = "hello"};
printf("%s", description[obj]);
}
λ gcc test.c -o a -Wall -Wextra
## Expected
A warning:
test.c:7:53: warning: initializer-string for array of ‘char’ is too long
7 | static const char description[][5] = {[hello] = "hello"};
## Actual
No warnings.
