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Re: Add macros for diagnostic control, use them in locale/weightwc.h
- From: Paul Eggert <eggert at cs dot ucla dot edu>
- To: Joseph Myers <joseph at codesourcery dot com>, libc-alpha at sourceware dot org
- Date: Tue, 18 Nov 2014 12:53:05 -0800
- Subject: Re: Add macros for diagnostic control, use them in locale/weightwc.h
- Authentication-results: sourceware.org; auth=none
- References: <alpine dot DEB dot 2 dot 10 dot 1411181803130 dot 11642 at digraph dot polyomino dot org dot uk>
On 11/18/2014 10:04 AM, Joseph Myers wrote:
+ DIAG_PUSH;
+#if __GNUC_PREREQ (4, 7)
+ DIAG_IGNORE (-Wmaybe-uninitialized, 4.9);
+#endif
if (cp[nhere - 1] > usrc[nhere -1])
{
cp += 2 * nhere;
@@ -105,6 +117,7 @@ findidx (const int32_t *table,
/* This range matches the next characters. Now find
the offset in the indirect table. */
offset = usrc[nhere - 1] - cp[nhere - 1];
+ DIAG_POP;
My kneejerk reaction is that attempting to minimize the scope of
disabled warnings will make code harder to read and maintain, and the
costs of minimization may outweigh the benefits.
Also, the distinction between GCC version "4, 7" (which is checked) and
version "4.9" (which is not) is bothersome. Inevitably the unchecked
version numbers will become wrong. If we're going to have a "4.9" at
all, we should check it.
How about the attached (untested) patch instead? This is simpler and
less intrusive and should scale better. It disables the diagnostic in
some places that it doesn't absolutely need to, but it separates
concerns better and overall I expect it would have a better
cost-to-benefit ratio.
diff --git a/ChangeLog b/ChangeLog
index 37b1459..ab9dc88 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2014-11-18 Paul Eggert <eggert@cs.ucla.edu>
+
+ * locale/weightwc.h (findidx): Disable -Wmaybe-uninitialized.
+
2014-11-18 Roland McGrath <roland@hack.frob.com>
* nptl/createthread.c: New file.
diff --git a/locale/weightwc.h b/locale/weightwc.h
index 0f70b00..383d34e 100644
--- a/locale/weightwc.h
+++ b/locale/weightwc.h
@@ -19,6 +19,14 @@
#ifndef _WEIGHTWC_H_
#define _WEIGHTWC_H_ 1
+#pragma GCC diagnostic push
+
+/* Seen on x86_64 (inlined from fnmatch_loop.c:internal_fnwmatch):
+ "'*((void *)&str+4)' may be used uninitialized in this function". */
+#if __GNUC_PREREQ (4, 7) && !__GNUC_PREPREQ (4, 10)
+# pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
+
/* Find index of weight. */
static inline int32_t __attribute__ ((always_inline))
findidx (const int32_t *table,
@@ -115,4 +123,6 @@ findidx (const int32_t *table,
return 0x43219876;
}
+#pragma GCC diagnostic pop
+
#endif /* weightwc.h */