https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97498
Bug ID: 97498
Summary: #pragma GCC diagnostic ignored "-Wunused-function"
inconsistent
Product: gcc
Version: 9.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: preprocessor
Assignee: unassigned at gcc dot gnu.org
Reporter: matthewp515 at gmail dot com
Target Milestone: ---
Ubuntu Linux 20.04
#define STR(x) #x
#define WIGNORE(x, instrs) \
_Pragma("GCC diagnostic push") \
_Pragma(STR(GCC diagnostic ignored #x)) \
instrs \
_Pragma("GCC diagnostic pop")
// REPLACE
int main(void) {return 1;}
When REPLACE is replaced with:
WIGNORE(-Wunused-function,
static int f(int a) {return a + 1;}
)
The command:
gcc main.c -Wall -Werror -Wextra
fails (-Werror=unused-function). However, breaking up the command into separate
preprocessing and compilation stages:
gcc -E main.c -Wall -Werror -Wextra | gcc -x c -
passes.
When the macro is unwound by REPLACE being replaced with:
_Pragma("GCC diagnostic push");
_Pragma("GCC diagnostic ignored \"-Wunused-function\"");
static int f(int p) {return p + 1;}
_Pragma("GCC diagnostic pop");
The first command then passes. By adding a single backslash (\) right after the
implementation of f, as is required to keep the WIGNORE macro all as one, the
command fails. But how else can the macro be constructed?
