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Re: [v1] Add Reiwa era tests to time/tst-strftime3.c

Steve Ellcey <> writes:
> tst-strftime3.c:443:62: error: ‘%s’ directive output may be truncated writing up to 49 bytes into a region of size between 0 and 30 [-Werror=format-truncation=]

Fixed thusly:

snprintf will only truncate the output if the data its given
is corrupted, but a truncated buffer will not match the
"pristine" data's buffer, which is all we need.  So just
disable the warning via the DIAG macros.

2019-04-03  DJ Delorie  <>

	* time/tst-strftime3.c (tm_to_printed): Disable warning about
	snprintf truncating output.

diff --git a/time/tst-strftime3.c b/time/tst-strftime3.c
index 32ce0d93e2..eeca0921cb 100644
--- a/time/tst-strftime3.c
+++ b/time/tst-strftime3.c
@@ -25,6 +25,7 @@
 #include <support/check.h>
 #include <array_length.h>
+#include <libc-diag.h>
 /* These exist for the convenience of writing the test data, because
    zero-based vs one-based.  */
@@ -440,6 +441,14 @@ tm_to_printed (struct tm *tm, char *buffer)
       sprintf (temp, "%d", tm->tm_wday);
+#if __GNUC_PREREQ (9, 0)
+  /* GCC 9 warns that strncmp may truncate its output, but that's why
+     we're using it.  When it needs to truncate, it got corrupted
+     data, and we only care that the string is different than valid
+     data, which won't truncate.  */
+  DIAG_IGNORE_NEEDS_COMMENT (9, "-Wformat-truncation=");
   snprintf (buffer, TMBUFLEN, "%04d/%02d/%02d %02d:%02d:%02d %s",
 	    tm->tm_year + 1900,
 	    tm->tm_mon + 1,
@@ -448,6 +457,7 @@ tm_to_printed (struct tm *tm, char *buffer)
 static int

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