Our code for handling the "_Pragma" builtin macro is implemented in
libcpp/directives.c:destringize_and_run.
It handles _Pragma by creating a one-line buffer containing the _Pragma
content, then sending it to do_pragma, which tokenizes it and handles
the input as if it were spelled as #pragma.
Unfortunately the tokens it generates have bogus location values; the
values are in the current highest ordinary map at the time of expansion,
and this determines the effective location of the synthesized #pragma.
Hence for PR preprocessor/69126:
VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV
#pragma GCC diagnostic push
#define MACRO \
_Pragma("GCC diagnostic ignored \"-Wunused-variable\"") \
int x;
int g()
{
MACRO;
return 0;
}
#pragma GCC diagnostic pop
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
although -save-temps looks sane:
VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV
#pragma GCC diagnostic push
int g()
{
# 19 "../../src/gcc/testsuite/c-c++-common/pr69126.c"
#pragma GCC diagnostic ignored "-Wunused-variable"
# 19 "../../src/gcc/testsuite/c-c++-common/pr69126.c"
int x;;
return 0;
}
#pragma GCC diagnostic pop
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
the "ignored" directive is treated as if it occured in this
bogus location:
(gdb) call inform (226930, "pre, the location of the ignore")
/tmp/test.cc:17:24: note: pre, the location of the ignore
MACRO;
^
which is effectively *after* the
int x;;
line.
I believe this is a long-standing bug, but the cleanup of the
C++ FE's impl of -Wunused-variable in r226234 (to avoid using
%q+D) has exposed this as a regression (since the -Wunused-variable
warning is now emitted for this location:
int x;
^
rather than at input_location:
return 0;
^
and hence isn't suppressed by the _Pragma.
The function destringize_and_run is full of comments like
/* Ugh; an awful kludge. We are really not set up to be lexing
and:
/* ??? Antique Disgusting Hack. What does this do? */
and similar "???" lines.
I believe it predates macro maps (I believe they were added in
r180081 on 2011-10-15); as far as I can tell, the code is set
up for *line* maps, i.e. it may even predate column information
(it gets the line right, but not the column).
To minimize the change to destringize_and_run at this stage, the
following patch papers over the problem by fixing up the locations
for the tokens synthesized for _Pragma, setting them all to be at the
expansion point of the _Pragma directive, rather than some columns
after it.
This fixes the location of the synthesized #pragma and hence
fixes the regression seen in the PR. The -save-temps output (which
was already correct) is unaffected.
Successfully bootstrapped®rtested on x86_64-pc-linux-gnu;
adds 3 PASS results to g++.sum and 1 to gcc.sum
(although the regression currently only affects C++, I put the new
test case into c-c++-common for good measure).
OK for trunk in stage 3?
gcc/testsuite/ChangeLog:
PR preprocessor/69126
* c-c++-common/pr69126.c: New test case.
libcpp/ChangeLog:
PR preprocessor/69126
* directives.c (destringize_and_run): Add expansion_loc param; use
it when handling unexpanded pragmas to fixup the locations of the
synthesized tokens.
(_cpp_do__Pragma): Add expansion_loc param and use it when calling
destringize_and_run.
* internal.h (_cpp_do__Pragma): Add expansion_loc param.
* macro.c (builtin_macro): Pass expansion location of _Pragma to
_cpp_do__Pragma.
---
gcc/testsuite/c-c++-common/pr69126.c | 22 ++++++++++++++++++++++
libcpp/directives.c | 13 ++++++++++---
libcpp/internal.h | 2 +-
libcpp/macro.c | 2 +-
4 files changed, 34 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/pr69126.c
diff --git a/gcc/testsuite/c-c++-common/pr69126.c
b/gcc/testsuite/c-c++-common/pr69126.c
new file mode 100644
index 0000000..fb4dcfb
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr69126.c
@@ -0,0 +1,22 @@
+/* { dg-options "-Wunused-variable" } */
+
+#pragma GCC diagnostic push
+int f()
+{
+ _Pragma("GCC diagnostic ignored \"-Wunused-variable\"")
+ int x;
+ return 0;
+}
+#pragma GCC diagnostic pop
+
+#pragma GCC diagnostic push
+#define MACRO \
+ _Pragma("GCC diagnostic ignored \"-Wunused-variable\"") \
+ int x;
+
+int g()
+{
+ MACRO;
+ return 0;
+}
+#pragma GCC diagnostic pop
diff --git a/libcpp/directives.c b/libcpp/directives.c
index eff1861..a1e1239 100644
--- a/libcpp/directives.c
+++ b/libcpp/directives.c
@@ -1753,7 +1753,8 @@ get__Pragma_string (cpp_reader *pfile)
/* Destringize IN into a temporary buffer, by removing the first \ of
\" and \\ sequences, and process the result as a #pragma directive. */
static void
-destringize_and_run (cpp_reader *pfile, const cpp_string *in)
+destringize_and_run (cpp_reader *pfile, const cpp_string *in,
+ source_location expansion_loc)
{
const unsigned char *src, *limit;
char *dest, *result;
@@ -1833,6 +1834,12 @@ destringize_and_run (cpp_reader *pfile, const cpp_string
*in)
toks = XRESIZEVEC (cpp_token, toks, maxcount);
}
toks[count] = *cpp_get_token (pfile);
+ /* _Pragma is a builtin, so we're not within a macro-map, and so
+ the token locations are set to bogus ordinary locations
+ near to, but after that of the "_Pragma".
+ Paper over this by setting them equal to the location of the
+ _Pragma itself (PR preprocessor/69126). */
+ toks[count].src_loc = expansion_loc;
/* Macros have been already expanded by cpp_get_token
if the pragma allowed expansion. */
toks[count++].flags |= NO_EXPAND;
@@ -1867,14 +1874,14 @@ destringize_and_run (cpp_reader *pfile, const
cpp_string *in)
/* Handle the _Pragma operator. Return 0 on error, 1 if ok. */
int
-_cpp_do__Pragma (cpp_reader *pfile)
+_cpp_do__Pragma (cpp_reader *pfile, source_location expansion_loc)
{
const cpp_token *string = get__Pragma_string (pfile);
pfile->directive_result.type = CPP_PADDING;
if (string)
{
- destringize_and_run (pfile, &string->val.str);
+ destringize_and_run (pfile, &string->val.str, expansion_loc);
return 1;
}
cpp_error (pfile, CPP_DL_ERROR,
diff --git a/libcpp/internal.h b/libcpp/internal.h
index e04ae68..bafd480 100644
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -688,7 +688,7 @@ extern int _cpp_handle_directive (cpp_reader *, int);
extern void _cpp_define_builtin (cpp_reader *, const char *);
extern char ** _cpp_save_pragma_names (cpp_reader *);
extern void _cpp_restore_pragma_names (cpp_reader *, char **);
-extern int _cpp_do__Pragma (cpp_reader *);
+extern int _cpp_do__Pragma (cpp_reader *, source_location);
extern void _cpp_init_directives (cpp_reader *);
extern void _cpp_init_internal_pragmas (cpp_reader *);
extern void _cpp_do_file_change (cpp_reader *, enum lc_reason, const char *,
diff --git a/libcpp/macro.c b/libcpp/macro.c
index ca1d1d6..cfb09ce 100644
--- a/libcpp/macro.c
+++ b/libcpp/macro.c
@@ -430,7 +430,7 @@ builtin_macro (cpp_reader *pfile, cpp_hashnode *node,
source_location loc)
if (pfile->state.in_directive)
return 0;
- return _cpp_do__Pragma (pfile);
+ return _cpp_do__Pragma (pfile, loc);
}
buf = _cpp_builtin_macro_text (pfile, node);
--
1.8.5.3
