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190 lines
7.1 KiB
190 lines
7.1 KiB
commit 2084e7ca4d344c39eb39e53848b51b5d84444414 |
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Author: Joseph Myers <joseph@codesourcery.com> |
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Date: Wed Dec 10 00:41:19 2014 +0000 |
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Add macros for diagnostic control, use for scanf %a tests. |
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In <https://sourceware.org/ml/libc-alpha/2014-11/msg00326.html>, |
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Roland requested internal macros for use of "#pragma GCC diagnostic". |
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This patch adds such macros and uses them to disable -Wformat warnings |
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for some code testing GNU scanf %as where GCC expects C99 scanf %a |
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(several other stdio tests currently use -Wno-format to disable |
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warnings). Limitations in GCC's diagnostic pragmas require separate |
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macros before and after the code generating the warnings, rather than |
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a single macro taking that code as an argument. |
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The macros are named DIAG_*_NEEDS_COMMENT to emphasise to reviewers |
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the need for a comment accompanying any use of them (such comments may |
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however just appear once for several uses of the macros for the same |
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issue in the same file). I put a GCC version in the arguments to |
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DIAG_IGNORE_NEEDS_COMMENT, as that seems something useful to grep for |
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when obsoleting support for an old GCC version and needing to decide |
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if warning-disabling code is still relevant. |
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These macros should be usable for replacing existing -Wno-* use in |
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makefiles (as also suggested by Roland), though I have no plans to |
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work on that (only on use of the macros in cases where warnings are |
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currently present that need disabling to use -Werror). |
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Tested for x86_64. |
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* include/libc-internal.h (DIAG_PUSH_NEEDS_COMMENT): New macro. |
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(DIAG_POP_NEEDS_COMMENT): Likewise. |
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(_DIAG_STR1): Likewise. |
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(_DIAG_STR): Likewise. |
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(DIAG_IGNORE_NEEDS_COMMENT): Likewise. |
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* stdio-common/bug21.c: Include <libc-internal.h>. |
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(do_test): Disable -Wformat around call to sscanf. |
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* stdio-common/scanf14.c: Include <libc-internal.h>. |
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(main): Disable -Wformat around some calls to scanf functions. |
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diff --git a/include/libc-internal.h b/include/libc-internal.h |
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index 2ced1c17d3dff93d..bca59a46144b736f 100644 |
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--- a/include/libc-internal.h |
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+++ b/include/libc-internal.h |
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@@ -76,4 +76,35 @@ extern void __init_misc (int, char **, char **); |
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#define ignore_value(x) \ |
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({ __typeof__ (x) __ignored_value = (x); (void) __ignored_value; }) |
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+/* The macros to control diagnostics are structured like this, rather |
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+ than a single macro that both pushes and pops diagnostic state and |
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+ takes the affected code as an argument, because the GCC pragmas |
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+ work by disabling the diagnostic for a range of source locations |
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+ and do not work when all the pragmas and the affected code are in a |
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+ single macro expansion. */ |
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+ |
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+/* Push diagnostic state. */ |
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+#define DIAG_PUSH_NEEDS_COMMENT _Pragma ("GCC diagnostic push") |
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+ |
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+/* Pop diagnostic state. */ |
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+#define DIAG_POP_NEEDS_COMMENT _Pragma ("GCC diagnostic pop") |
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+ |
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+#define _DIAG_STR1(s) #s |
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+#define _DIAG_STR(s) _DIAG_STR1(s) |
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+ |
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+/* Ignore the diagnostic OPTION. VERSION is the most recent GCC |
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+ version for which the diagnostic has been confirmed to appear in |
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+ the absence of the pragma (in the form MAJOR.MINOR for GCC 4.x, |
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+ just MAJOR for GCC 5 and later). Uses of this pragma should be |
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+ reviewed when the GCC version given is no longer supported for |
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+ building glibc; the version number should always be on the same |
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+ source line as the macro name, so such uses can be found with grep. |
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+ Uses should come with a comment giving more details of the |
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+ diagnostic, and an architecture on which it is seen if possibly |
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+ optimization-related and not in architecture-specific code. This |
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+ macro should only be used if the diagnostic seems hard to fix (for |
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+ example, optimization-related false positives). */ |
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+#define DIAG_IGNORE_NEEDS_COMMENT(version, option) \ |
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+ _Pragma (_DIAG_STR (GCC diagnostic ignored option)) |
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+ |
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#endif /* _LIBC_INTERNAL */ |
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diff --git a/stdio-common/bug21.c b/stdio-common/bug21.c |
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index d22b9c1a9717a197..ca27272ba191321e 100644 |
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--- a/stdio-common/bug21.c |
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+++ b/stdio-common/bug21.c |
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@@ -1,4 +1,5 @@ |
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#include <stdio.h> |
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+#include <libc-internal.h> |
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static int |
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do_test (void) |
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@@ -6,7 +7,15 @@ do_test (void) |
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static const char buf[] = " "; |
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char *str; |
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+ /* GCC in C99 mode treats %a as the C99 format expecting float *, |
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+ but glibc with _GNU_SOURCE treats %as as the GNU allocation |
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+ extension, so resulting in "warning: format '%a' expects argument |
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+ of type 'float *', but argument 3 has type 'char **'". This |
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+ applies to the other %as, %aS and %a[] formats below as well. */ |
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+ DIAG_PUSH_NEEDS_COMMENT; |
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+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat"); |
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int r = sscanf (buf, "%as", &str); |
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+ DIAG_POP_NEEDS_COMMENT; |
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printf ("%d %p\n", r, str); |
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return r != -1 || str != NULL; |
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diff --git a/stdio-common/scanf14.c b/stdio-common/scanf14.c |
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index 6ca5c7c5679632a3..cffccb0b19d2927b 100644 |
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--- a/stdio-common/scanf14.c |
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+++ b/stdio-common/scanf14.c |
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@@ -2,6 +2,7 @@ |
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#include <stdlib.h> |
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#include <string.h> |
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#include <wchar.h> |
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+#include <libc-internal.h> |
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#define FAIL() \ |
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do { \ |
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@@ -23,6 +24,13 @@ main (void) |
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FAIL (); |
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else if (f != 0.25 || memcmp (c, "s x", 3) != 0) |
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FAIL (); |
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+ /* GCC in C99 mode treats %a as the C99 format expecting float *, |
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+ but glibc with _GNU_SOURCE treats %as as the GNU allocation |
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+ extension, so resulting in "warning: format '%a' expects argument |
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+ of type 'float *', but argument 3 has type 'char **'". This |
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+ applies to the other %as, %aS and %a[] formats below as well. */ |
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+ DIAG_PUSH_NEEDS_COMMENT; |
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+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat"); |
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if (sscanf (" 1.25s x", "%as%2c", &sp, c) != 2) |
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FAIL (); |
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else |
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@@ -32,10 +40,14 @@ main (void) |
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memset (sp, 'x', sizeof "1.25s"); |
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free (sp); |
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} |
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+ DIAG_POP_NEEDS_COMMENT; |
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if (sscanf (" 2.25s x", "%las%2c", &d, c) != 2) |
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FAIL (); |
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else if (d != 2.25 || memcmp (c, " x", 2) != 0) |
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FAIL (); |
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+ /* See explanation above. */ |
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+ DIAG_PUSH_NEEDS_COMMENT; |
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+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat"); |
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if (sscanf (" 3.25S x", "%4aS%3c", &lsp, c) != 2) |
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FAIL (); |
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else |
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@@ -54,6 +66,7 @@ main (void) |
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memset (sp, 'x', sizeof "4.25"); |
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free (sp); |
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} |
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+ DIAG_POP_NEEDS_COMMENT; |
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if (sscanf ("5.25[0-9.] x", "%la[0-9.]%2c", &d, c) != 2) |
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FAIL (); |
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else if (d != 5.25 || memcmp (c, " x", 2) != 0) |
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@@ -82,6 +95,9 @@ main (void) |
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FAIL (); |
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if (fseek (fp, 0, SEEK_SET) != 0) |
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FAIL (); |
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+ /* See explanation above. */ |
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+ DIAG_PUSH_NEEDS_COMMENT; |
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+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat"); |
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if (fscanf (fp, "%as%2c", &sp, c) != 2) |
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FAIL (); |
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else |
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@@ -91,11 +107,15 @@ main (void) |
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memset (sp, 'x', sizeof "1.25s"); |
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free (sp); |
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} |
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+ DIAG_POP_NEEDS_COMMENT; |
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if (freopen (fname, "r", stdin) == NULL) |
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FAIL (); |
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else |
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{ |
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+ /* See explanation above. */ |
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+ DIAG_PUSH_NEEDS_COMMENT; |
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+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat"); |
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if (scanf ("%as%2c", &sp, c) != 2) |
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FAIL (); |
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else |
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@@ -105,6 +125,7 @@ main (void) |
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memset (sp, 'x', sizeof "1.25s"); |
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free (sp); |
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} |
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+ DIAG_POP_NEEDS_COMMENT; |
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} |
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fclose (fp);
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