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libcpp: Fix up #__VA_OPT__ handling [PR103415] 

stringify_arg uses pfile->u_buff to create the string literal.
Unfortunately, paste_tokens -> _cpp_lex_direct -> lex_number -> _cpp_unaligned_alloc
can in some cases use pfile->u_buff too, which results in losing everything
prepared for the string literal until the token pasting.

The following patch fixes that by not calling paste_token during the
construction of the string literal, but doing that before.  All the tokens
we are processing have been pushed into a token buffer using
tokens_buff_add_token so it is fine if we paste some of them in that buffer
(successful pasting creates a new token in that buffer), move following
tokens if any to make it contiguous, pop (throw away) the extra tokens at
the end and then do stringify_arg.

Also, paste_tokens now copies over PREV_WHITE and PREV_FALLTHROUGH flags
from the original lhs token to the replacement token.  Copying that way
the PREV_WHITE flag is needed for the #__VA_OPT__ handling and copying
over PREV_FALLTHROUGH fixes the new Wimplicit-fallthrough-38.c test.

2021-12-01  Jakub Jelinek  <jakub@redhat.com>

	PR preprocessor/103415
libcpp/
	* macro.c (stringify_arg): Remove va_opt argument and va_opt handling.
	(paste_tokens): On successful paste or in PREV_WHITE and
	PREV_FALLTHROUGH flags from the *plhs token to the new token.
	(replace_args): Adjust stringify_arg callers.  For #__VA_OPT__,
	perform token pasting in a separate loop before stringify_arg call.
gcc/testsuite/
	* c-c++-common/cpp/va-opt-8.c: New test.
	* c-c++-common/Wimplicit-fallthrough-38.c: New test.
This commit is contained in:
Jakub Jelinek 2021-12-01 10:07:59 +01:00
parent 29df53fe34
commit ac5fd364f0
3 changed files with 86 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
gcc/testsuite/c-c++-common/Wimplicit-fallthrough-38.c Normal file
View File

@ -0,0 +1,24 @@
/* { dg-do compile } */
/* { dg-options "-Wimplicit-fallthrough=3" } */
#define FOO \
int \
foo (int a) \
{ \
switch (a) \
{ \
case 1: \
++a; \
/* FALLTHRU */ \
case 2: \
++a; \
/* FALLTHRU */ \
ca##se 3: \
++a; \
default: \
break; \
} \
return a; \
}
FOO

18
gcc/testsuite/c-c++-common/cpp/va-opt-8.c Normal file
View File

@ -0,0 +1,18 @@
/* PR preprocessor/103415 */
/* { dg-do run } */
/* { dg-options "-std=gnu99" { target c } } */
/* { dg-options "-std=c++20" { target c++ } } */
#define n(x, ...) = #__VA_OPT__(x##3)
#define o(x, ...) #__VA_OPT__(x##__VA_ARGS__##9)
const char *c n(1 2, 4);
const char *d = o(5 6, 7 8);
int
main ()
{
if (__builtin_strcmp (c, "1 23")
|| __builtin_strcmp (d, "5 67 89"))
__builtin_abort ();
return 0;
}

72
libcpp/macro.c
View File

@ -295,7 +295,7 @@ static cpp_context *next_context (cpp_reader *);
static const cpp_token *padding_token (cpp_reader *, const cpp_token *);
static const cpp_token *new_string_token (cpp_reader *, uchar *, unsigned int);
static const cpp_token *stringify_arg (cpp_reader *, const cpp_token **,
unsigned int, bool);
unsigned int);
static void paste_all_tokens (cpp_reader *, const cpp_token *);
static bool paste_tokens (cpp_reader *, location_t,
const cpp_token **, const cpp_token *);
@ -834,8 +834,7 @@ cpp_quote_string (uchar *dest, const uchar *src, unsigned int len)
/* Convert a token sequence FIRST to FIRST+COUNT-1 to a single string token
according to the rules of the ISO C #-operator. */
static const cpp_token *
stringify_arg (cpp_reader *pfile, const cpp_token **first, unsigned int count,
bool va_opt)
stringify_arg (cpp_reader *pfile, const cpp_token **first, unsigned int count)
{
unsigned char *dest;
unsigned int i, escape_it, backslash_count = 0;
@ -852,24 +851,6 @@ stringify_arg (cpp_reader *pfile, const cpp_token **first, unsigned int count,
{
const cpp_token *token = first[i];
if (va_opt && (token->flags & PASTE_LEFT))
{
location_t virt_loc = pfile->invocation_location;
const cpp_token *rhs;
do
{
if (i == count)
abort ();
rhs = first[++i];
if (!paste_tokens (pfile, virt_loc, &token, rhs))
{
--i;
break;
}
}
while (rhs->flags & PASTE_LEFT);
}
if (token->type == CPP_PADDING)
{
if (source == NULL
@ -1003,6 +984,7 @@ paste_tokens (cpp_reader *pfile, location_t location,
return false;
}
lhs->flags |= (*plhs)->flags & (PREV_WHITE | PREV_FALLTHROUGH);
*plhs = lhs;
_cpp_pop_buffer (pfile);
return true;
@ -1945,8 +1927,7 @@ replace_args (cpp_reader *pfile, cpp_hashnode *node, cpp_macro *macro,
if (src->flags & STRINGIFY_ARG)
{
if (!arg->stringified)
arg->stringified = stringify_arg (pfile, arg->first, arg->count,
false);
arg->stringified = stringify_arg (pfile, arg->first, arg->count);
}
else if ((src->flags & PASTE_LEFT)
|| (src != macro->exp.tokens && (src[-1].flags & PASTE_LEFT)))
@ -2066,11 +2047,46 @@ replace_args (cpp_reader *pfile, cpp_hashnode *node, cpp_macro *macro,
{
unsigned int count
= start ? paste_flag - start : tokens_buff_count (buff);
const cpp_token *t
= stringify_arg (pfile,
start ? start + 1
: (const cpp_token **) (buff->base),
count, true);
const cpp_token **first
= start ? start + 1
: (const cpp_token **) (buff->base);
unsigned int i, j;
/* Paste any tokens that need to be pasted before calling
stringify_arg, because stringify_arg uses pfile->u_buff
which paste_tokens can use as well. */
for (i = 0, j = 0; i < count; i++, j++)
{
const cpp_token *token = first[i];
if (token->flags & PASTE_LEFT)
{
location_t virt_loc = pfile->invocation_location;
const cpp_token *rhs;
do
{
if (i == count)
abort ();
rhs = first[++i];
if (!paste_tokens (pfile, virt_loc, &token, rhs))
{
--i;
break;
}
}
while (rhs->flags & PASTE_LEFT);
}
first[j] = token;
}
if (j != i)
{
while (i-- != j)
tokens_buff_remove_last_token (buff);
count = j;
}
const cpp_token *t = stringify_arg (pfile, first, count);
while (count--)
tokens_buff_remove_last_token (buff);
if (src->flags & PASTE_LEFT)