As mentioned in the PR, in some cases we preprocess incorrectly when we
encounter an identifier which is defined as function-like macro, followed
by at least 2 CPP_PADDING tokens and then some other identifier.
On the following testcase, the problem is in the 3rd funlike_invocation_p,
the tokens are CPP_NAME Y, CPP_PADDING (the pfile->avoid_paste shared token),
CPP_PADDING (one created with padding_token, val.source is non-NULL and
val.source->flags & PREV_WHITE is non-zero) and then another CPP_NAME.
funlike_invocation_p remembers there was a padding token, but remembers the
first one because of its condition, then the next token is the CPP_NAME,
which is not CPP_OPEN_PAREN, so the CPP_NAME token is backed up, but as we
can't easily backup more tokens, it pushes into a new context the padding
token (the pfile->avoid_paste one). The net effect is that when Y is not
defined as fun-like macro, we read Y, avoid_paste, padding_token, Y,
while if Y is fun-like macro, we read Y, avoid_paste, avoid_paste, Y
(the second avoid_paste is because that is how we handle end of a context).
Now, for stringify_arg that is unfortunately a significant difference,
which handles CPP_PADDING tokens with:
if (token->type == CPP_PADDING)
{
if (source == NULL
|| (!(source->flags & PREV_WHITE)
&& token->val.source == NULL))
source = token->val.source;
continue;
}
and later on
/* Leading white space? */
if (dest - 1 != BUFF_FRONT (pfile->u_buff))
{
if (source == NULL)
source = token;
if (source->flags & PREV_WHITE)
*dest++ = ' ';
}
source = NULL;
(and c-ppoutput.cc has similar code).
So, when Y is not fun-like macro, ' ' is added because padding_token's
val.source->flags & PREV_WHITE is non-zero, while when it is fun-like
macro, we don't add ' ' in between, because source is NULL and so
used from the next token (CPP_NAME Y), which doesn't have PREV_WHITE set.
Now, the funlike_invocation_p condition
if (padding == NULL
|| (!(padding->flags & PREV_WHITE) && token->val.source == NULL))
padding = token;
looks very similar to that in stringify_arg/c-ppoutput.cc, so I assume
the intent was to prefer do the same thing and pick the right padding.
But there are significant differences. Both stringify_arg and c-ppoutput.cc
don't remember the CPP_PADDING token, but its val.source instead, while
in funlike_invocation_p we want to remember the padding token that has the
significant information for stringify_arg/c-ppoutput.cc.
So, IMHO we want to overwrite padding if:
1) padding == NULL (remember that there was any padding at all)
2) padding->val.source == NULL (this matches the source == NULL
case in stringify_arg)
3) !(padding->val.source->flags & PREV_WHITE) && token->val.source == NULL
(this matches the !(source->flags & PREV_WHITE) && token->val.source == NULL
case in stringify_arg)
2022-02-01 Jakub Jelinek <jakub@redhat.com>
PR preprocessor/104147
* macro.cc (funlike_invocation_p): For padding prefer a token
with val.source non-NULL especially if it has PREV_WHITE set
on val.source->flags. Add gcc_assert that CPP_PADDING tokens
don't have PREV_WHITE set in flags.
* c-c++-common/cpp/pr104147.c: New test.
95ac563540