> I can directly inspect the result of the preprocessor makes macros easier to debug
Tangential note but: why does this require a separate re-invocation of the compiler with the '-E' flag? Say I have this silly example with a comma instead of the semicolon inside W() macro:
#define W(a, b) b, int a
#define X(a, b) W(b, a)
int kekw(int x) {
int z = X(23, k) = x;
return z + k;
}
When I shove it into GCC without -E, it says
<source>: In function 'int kekw(int)':
<source>:1:21: error: expected unqualified-id before 'int'
1 | #define W(a, b) b, int a
| ^~~
<source>:2:18: note: in expansion of macro 'W'
2 | #define X(a, b) W(b, a)
| ^
<source>:5:13: note: in expansion of macro 'X'
5 | int z = X(23, k) = x;
| ^
<source>:6:16: error: 'k' was not declared in this scope
6 | return z + k;
|
instead of, you know, showing me the expanded text so that I could see what's actually wrong with the generated variable declarations? Something like
<source>: In function 'int kekw(int)':
<source>:1:21: error: expected unqualified-id before 'int'
1 | #define W(a, b) b, int a
| ^~~
<source>:2:18: note: in expansion of macro 'W'
2 | #define X(a, b) W(b, a)
| ^
<source>:5:13: note: in expansion of macro 'X'
5 | int z = X(23, k) = x;
| ^
<source>:5:-: note: the expanded source text is
| int z = 23, int k = x;
| ^~~
<source>:6:16: error: 'k' was not declared in this scope
6 | return z + k;
|
perhaps? I understand that tracking the lines/columns inside the expanded text is highly non-trivial (although collapsing them all onto the position of the top-level macro is already just as non-trivial), but still. Show me what the source that you actually can't compile, not the three-steps removed precursor to it — I sure as hell can't expand macros in my head.
Also, what is this first error message about in the first place? Why the hell does it expect unqualified-id before "int"? If you put "int" after the unqualified-id, it still would be illegal; and an unqualified-id is not the only thing that can follow the comma in this context anyway.
Tangential note but: why does this require a separate re-invocation of the compiler with the '-E' flag? Say I have this silly example with a comma instead of the semicolon inside W() macro:
When I shove it into GCC without -E, it says instead of, you know, showing me the expanded text so that I could see what's actually wrong with the generated variable declarations? Something like perhaps? I understand that tracking the lines/columns inside the expanded text is highly non-trivial (although collapsing them all onto the position of the top-level macro is already just as non-trivial), but still. Show me what the source that you actually can't compile, not the three-steps removed precursor to it — I sure as hell can't expand macros in my head.Also, what is this first error message about in the first place? Why the hell does it expect unqualified-id before "int"? If you put "int" after the unqualified-id, it still would be illegal; and an unqualified-id is not the only thing that can follow the comma in this context anyway.