libcpp: Fix macro expansion for argument of __has_include [PR110558]
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Commit Message
Hello-
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110558
This is a small fix for the libcpp issue noted in the PR. Bootstrap +
regtest all languages on x86-64 Linux. Is it ok for trunk please?
Also, it's not a regression, having never worked since __has_include was
introduced in GCC 5, but FWIW the fix would backport fine to all branches
since then... so I think backport to 11,12,13 would make sense assuming the
patch is OK. Thanks!
-Lewis
-- >8 --
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.
---
libcpp/macro.cc | 3 +++
gcc/testsuite/c-c++-common/cpp/has-include-2.c | 12 ++++++++++++
gcc/testsuite/c-c++-common/cpp/has-include-2.h | 1 +
3 files changed, 16 insertions(+)
create mode 100644 gcc/testsuite/c-c++-common/cpp/has-include-2.c
create mode 100644 gcc/testsuite/c-c++-common/cpp/has-include-2.h
Comments
On Tue, 12 Dec 2023, Lewis Hyatt wrote:
> 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.
OK.
@@ -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;
new file mode 100644
@@ -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
new file mode 100644
@@ -0,0 +1 @@
+/* PR preprocessor/110558 */