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libcpp: Fix macro expansion for argument of __has_include [PR110558]

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When the file name for a #include directive is the result of stringifying a
macro argument, libcpp needs to take some care to get the whitespace
correct; in particular stringify_arg() needs to see a CPP_PADDING token
between macro tokens so that it can figure out when to output space between
tokens. The CPP_PADDING tokens are not normally generated when handling a
preprocessor directive, but for #include-like directives, libcpp sets the
state variable pfile->state.directive_wants_padding to TRUE so that the
CPP_PADDING tokens will be output, and then everything works fine for
computed includes.

As the PR points out, things do not work fine for __has_include. Fix that by
setting the state variable the same as is done for #include.

libcpp/ChangeLog:

	PR preprocessor/110558
	* macro.cc (builtin_has_include): Set
	pfile->state.directive_wants_padding prior to lexing the
	file name, in case it comes from macro expansion.

gcc/testsuite/ChangeLog:

	PR preprocessor/110558
	* c-c++-common/cpp/has-include-2.c: New test.
	* c-c++-common/cpp/has-include-2.h: New test.
This commit is contained in:
Lewis Hyatt 2023-12-12 17:46:36 -05:00
parent 6c166e55b1
commit 942497ad74
3 changed files with 16 additions and 0 deletions
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12
gcc/testsuite/c-c++-common/cpp/has-include-2.c Normal file
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@ -0,0 +1,12 @@
/* PR preprocessor/110558 */
/* { dg-do preprocess } */
#define STRINGIZE(x) #x
#define GET_INCLUDE(i) STRINGIZE(has-include-i.h)
/* Spaces surrounding the macro args previously caused a problem for __has_include(). */
#if __has_include(GET_INCLUDE(2)) && __has_include(GET_INCLUDE( 2)) && __has_include(GET_INCLUDE( 2 ))
#include GET_INCLUDE(2)
#include GET_INCLUDE( 2)
#include GET_INCLUDE( 2 )
#else
#error "__has_include did not handle padding properly" /* { dg-bogus "__has_include" } */
#endif

1
gcc/testsuite/c-c++-common/cpp/has-include-2.h Normal file
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@ -0,0 +1 @@
/* PR preprocessor/110558 */

3
libcpp/macro.cc
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@ -398,6 +398,8 @@ builtin_has_include (cpp_reader *pfile, cpp_hashnode *op, bool has_next)
NODE_NAME (op));
pfile->state.angled_headers = true;
const auto sav_padding = pfile->state.directive_wants_padding;
pfile->state.directive_wants_padding = true;
const cpp_token *token = cpp_get_token_no_padding (pfile);
bool paren = token->type == CPP_OPEN_PAREN;
if (paren)
@ -406,6 +408,7 @@ builtin_has_include (cpp_reader *pfile, cpp_hashnode *op, bool has_next)
cpp_error (pfile, CPP_DL_ERROR,
"missing '(' before \"%s\" operand", NODE_NAME (op));
pfile->state.angled_headers = false;
pfile->state.directive_wants_padding = sav_padding;
bool bracket = token->type != CPP_STRING;
char *fname = NULL;