On Thu, Feb 22, 2024 at 05:49:12PM +0000, Joseph Myers wrote:
> This patch (the one using COLON_SCOPE, *not* the one using PREV_WHITE) is
> OK.
>
> PREV_WHITE is about whether there is whitespace between the tokens in the
> macro expansion, for the purposes of stringization - I don't think it's
> appropriate to use here. For example, given
>
> #define COLON() :
>
> then
>
> [[gnu COLON()COLON() unused]] int x;
>
> should preferably not be valid; stringizing the results of expanding
> COLON()COLON() will produce "::" (PREV_WHITE not set), but that wouldn't
> be a valid attribute in C23 and I don't think anyone could reasonably
> expect it to be valid with previous standard versions.
It is not valid in either version of the patch, with any of -std=c11,
-std=gnu11 or -std=c23 with both compilers I get the same
/tmp/test.c:2:1: warning: ‘gnu’ attribute ignored [-Wattributes]
2 | [[gnu COLON()COLON() unused]] int x;
| ^
/tmp/test.c:2:6: error: expected ‘]’ before ‘:’ token
2 | [[gnu COLON()COLON() unused]] int x;
| ^
| ]
message all the time.
But sure, if you prefer the COLON_SCOPE version of the patch, I can commit
that. There is no PREV_WHITE in the preprocessor, there is
CPP_PADDING token in between the CPP_COLONs though and that translates
into PREV_WHITE on the second CPP_COLON in the FE token.
When trying to verify it, I've noticed one typo in the PREV_WHITE patch:
@@ -73,7 +73,7 @@ gcc/testsuite/
switch (type)
{
case CPP_PADDING:
-+ add_flags |= CPP_PADDING;
++ add_flags |= PREV_WHITE;
goto retry;
case CPP_NAME:
but it doesn't change anything on the outcome of those tests nor your
testcase above nor the C++ -std=c++98 -fpermissive test. CPP_PADDING
is 85 and PREV_WHITE 1, so it was setting PREV_WHITE too (just 3 other flags
too).
Jakub
