Martin Sebor wrote:
On 11/22/20 8:34 AM, emre brookes wrote:
I was compiling a project and received an odd message that took some
digging.
e.g.
file.cpp:#:#: error: expected unqualified-id before numeric constant
# | if ( inttype == MyClass::ERROR )
^~~~~
where MyClass::ERROR is an enum.
Took some digging to find out ERROR was somewhere #define'd and the
cure was to #undef ERROR
Could never find out *where* it was defined - recursively searched
all include files of the project and /usr/include etc.
Regardless, it would have been very helpful to know in the error
messages that a #define was active or to have the ERROR replaced by
the macro substitution.
Is it possible to get any macro expansion information in error messages?
I didn't see a compiler flag for to get this information, but I might
have missed it.
If not, it would be a nice feature to have.
I'd expect to see output similar to the below where the error points
to the macro. I'm not sure under what conditions it won't (with some
specific options perhaps?) If you can create an isolated test case
showing it doesn't I'd recommend to open a bug in Bugzilla (or just
follow up here).
Martin
$ cat a.C && gcc -S a.C
struct MyClass { enum { ERROR = 1 }; };
#define ERROR 1
int f (int inttype)
{
if (inttype == MyClass::ERROR)
return 0;
return 1;
}
a.C: In function ‘int f(int)’:
a.C:3:15: error: expected unqualified-id before numeric constant
3 | #define ERROR 1
| ^
a.C:7:27: note: in expansion of macro ‘ERROR’
7 | if (inttype == MyClass::ERROR)
| ^~~~~
a.C:7:25: error: expected ‘)’ before numeric constant
7 | if (inttype == MyClass::ERROR)
| ~ ^
| )
.
I get the same results for your example code. Here gcc nicely identifies
the macro expansion :)
Will test later with compiler flags from the project's Makefile add see
if I can reproduce the issue I observed on a simple case.
Thanks,
Emre
