* [wwwdocs] gcc-4.6/porting_to.html
@ 2011-03-17 6:51 Benjamin Kosnik
2011-03-17 7:59 ` Hans-Peter Nilsson
` (4 more replies)
0 siblings, 5 replies; 11+ messages in thread
From: Benjamin Kosnik @ 2011-03-17 6:51 UTC (permalink / raw)
To: gcc-patches
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Needs some more work, here's a rough draft.
-benjamin
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Index: htdocs/gcc-4.6/porting_to.html
===================================================================
RCS file: htdocs/gcc-4.6/porting_to.html
diff -N htdocs/gcc-4.6/porting_to.html
*** /dev/null 1 Jan 1970 00:00:00 -0000
--- htdocs/gcc-4.6/porting_to.html 17 Mar 2011 06:47:42 -0000
***************
*** 0 ****
--- 1,167 ----
+ <html>
+
+ <head>
+ <title>GCC 4.6 Release Series — Porting to the New Tools</title>
+ </head>
+
+ <body>
+ <h1>GCC 4.6 Release Series<br />Porting to the New Tools</h1>
+
+ <p>
+ The GCC 4.6 release series differs from previous GCC releases in more
+ than the usual list
+ of <a href="http://gcc.gnu.org/gcc-4.6/changes.html">new
+ features</a>. Some of these changes are a result of bug fixing, and
+ some old behaviors have been intentionally changed in order to support
+ new standards, or relaxed in standards-conforming ways to facilitate
+ compilation or runtime performance. Some of these changes are not
+ visible to the naked eye, and will not cause problems when updating
+ from older GCC versions.
+ </p>
+
+ <p>
+ However, some of these changes are visible, and can cause grief to
+ users porting to GCC 4.6. This document is an effort to identify major
+ issues and provide clear solutions in a quick and easily-searched
+ manner. Additions and suggestions for improvement are welcome.
+ </p>
+
+ <h3>C language issues</h3>
+
+ <h4>New warnings for unused variables and parameters</h4>
+
+ <p>
+ The behavior of <code>-Wall</code> has changed and now includes the
+ new warning flags <code>-Wunused-but-set-variable</code> and
+ (with <code>-Wall
+ -Wextra</code>) <code>-Wunused-but-set-parameter</code>. This may
+ result in new warnings in code that compiled cleanly with previous
+ versions of GCC.
+ </p>
+
+ <p>
+ For example,
+ </p>
+
+ <pre>
+ void fn (void)
+ {
+ int foo;
+ foo = bar (); /* foo is never used. */
+ }
+ </pre>
+
+ <p>
+ Gives the following diagnostic:
+ </p>
+
+ <pre>
+ warning: variable ‘foo’ set but not used [-Wunused-but-set-variable]
+ </pre>
+
+ <p> Although these warnings will
+ not result in compilation failure, often <code>-Wall</code> is used in
+ conjunction with <code>-Werror</code> and as a result, new warnings
+ are turned into new errors.
+ </p>
+
+ <p>
+ To fix, first see if the unused variable or parameter can be removed
+ without changing the result or logic of the surrounding code. If not,
+ annoate it with <code>__attribute__((__unused__))</code>
+ </p>
+
+ <p>As a workaround, remove <code>-Werror</code> until the new warnings
+ are fixed, or for conversion warnings
+ add <code>-Wno-unused-but-set-variable</code>
+ or <code>-Wno-unused-but-set-parameter</code>.
+ </p>
+
+ <h4>Strict overflow warnings</h4>
+
+ <p>
+ Using the <code>-Wstrict-overflow</code> flag
+ with <code>-Werror</code> and optmization flags above <code>-O2</code>
+ may result in compile errors when using glibc optimizations
+ for <code>strcmp</code>.
+ </p>
+
+ <p>
+ For example,
+ </p>
+
+ <pre>
+ #include <string.h>
+ void do_rm_rf (const char *p) { if (strcmp (p, "/") == 0) return; }
+ </pre>
+
+ <p>
+ Results in the following diagnostic:
+ </p>
+
+ <pre>
+ error: assuming signed overflow does not occur when changing X +- C1 cmp C2 to X cmp C1 +- C2 [-Werror=strict-overflow]
+ </pre>
+
+ <p>
+ To work around this, use </code>-D__NO_STRING_INLINES</code>.
+ </p>
+
+ <h3>C++ language issues</h3>
+
+ <h4>Header dependency changes</h4>
+
+ <p>
+ Many of the standard C++ library include files have been edited to no
+ longer include <cstddef> to get <code>namespace std</code>
+ -scoped versions of <code>size_t</code> and <code>ptrdiff_t</code>.
+ </p>
+
+ <p>
+ As such, C++ programs that used the macros <code>NULL</code>
+ or <code>offsetof</code> without including <cstddef> will no
+ longer compile. The diagnostic produced is similar to:
+ </p>
+
+ <pre>
+ error: 'ptrdiff_t' does not name a type
+ </pre>
+
+ <pre>
+ error: 'size_t' has not been declared
+ </pre>
+
+ <pre>
+ error: 'NULL' was not declared in this scope
+ </pre>
+
+ <pre>
+ error: there are no arguments to 'offsetof' that depend on a template
+ parameter, so a declaration of 'offsetof' must be available
+ </pre>
+
+ <p>
+ Fixing this issue is easy, just include <cstddef>.
+ </p>
+
+ <h3>Java issues</h3>
+
+ <h3>Links</h3>
+
+ <p>
+ Jakub Jelinek, <a href="http://lists.fedoraproject.org/pipermail/devel/2011-February/148523.html">GCC 4.6 related common package rebuild failures (was Re: mass rebuild status)</a>
+ </p>
+
+ <p>
+ Matthias Klose, <a href="http://lists.debian.org/debian-devel-announce/2011/02/msg00012.html">prepare to fix build failures with new GCC versions</a>
+ </p>
+
+ <p>
+ Jim Meyering, <a href="http://lists.fedoraproject.org/pipermail/devel/2011-March/149355.html">gcc-4.6.0-0.12.fc15.x86_64 breaks strcmp?</a>
+ </p>
+ <!-- ==================================================================== -->
+
+ </body>
+ </html>
+
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [wwwdocs] gcc-4.6/porting_to.html
2011-03-17 6:51 [wwwdocs] gcc-4.6/porting_to.html Benjamin Kosnik
@ 2011-03-17 7:59 ` Hans-Peter Nilsson
2011-03-17 8:11 ` Jakub Jelinek
` (3 subsequent siblings)
4 siblings, 0 replies; 11+ messages in thread
From: Hans-Peter Nilsson @ 2011-03-17 7:59 UTC (permalink / raw)
To: Benjamin Kosnik; +Cc: gcc-patches
On Wed, 16 Mar 2011, Benjamin Kosnik wrote:
> Needs some more work, here's a rough draft.
s/Porting to the new tools/Porting to the new version/
?
brgds, H-P
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [wwwdocs] gcc-4.6/porting_to.html
2011-03-17 6:51 [wwwdocs] gcc-4.6/porting_to.html Benjamin Kosnik
2011-03-17 7:59 ` Hans-Peter Nilsson
@ 2011-03-17 8:11 ` Jakub Jelinek
2011-03-17 11:45 ` Ryan Hill
` (2 subsequent siblings)
4 siblings, 0 replies; 11+ messages in thread
From: Jakub Jelinek @ 2011-03-17 8:11 UTC (permalink / raw)
To: Benjamin Kosnik; +Cc: gcc-patches
On Wed, Mar 16, 2011 at 11:51:30PM -0700, Benjamin Kosnik wrote:
> + <p>
> + To fix, first see if the unused variable or parameter can be removed
> + without changing the result or logic of the surrounding code. If not,
> + annoate it with <code>__attribute__((__unused__))</code>
annotate
Also, I think we should mention that casting the var to void is another
option.
And I think it is worth mentioning that sometimes the RHS can have important
side-effects, in which case it is desirable to just drop the LHS and =,
while sometimes the RHS is just uselessly computed and can be dropped
altogether with the assignment and unused variable.
> + <h4>Strict overflow warnings</h4>
> +
> + <p>
> + Using the <code>-Wstrict-overflow</code> flag
> + with <code>-Werror</code> and optmization flags above <code>-O2</code>
> + may result in compile errors when using glibc optimizations
> + for <code>strcmp</code>.
> + </p>
> +
> + <p>
> + For example,
> + </p>
> +
> + <pre>
> + #include <string.h>
> + void do_rm_rf (const char *p) { if (strcmp (p, "/") == 0) return; }
> + </pre>
This has been actually fixed, so we shouldn't mention this.
> + <p>
> + Jim Meyering, <a href="http://lists.fedoraproject.org/pipermail/devel/2011-March/149355.html">gcc-4.6.0-0.12.fc15.x86_64 breaks strcmp?</a>
And this reference too.
Thanks for writing this.
Jakub
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [wwwdocs] gcc-4.6/porting_to.html
2011-03-17 6:51 [wwwdocs] gcc-4.6/porting_to.html Benjamin Kosnik
2011-03-17 7:59 ` Hans-Peter Nilsson
2011-03-17 8:11 ` Jakub Jelinek
@ 2011-03-17 11:45 ` Ryan Hill
2011-03-17 13:59 ` Matthias Klose
2011-10-11 8:18 ` Gerald Pfeifer
4 siblings, 0 replies; 11+ messages in thread
From: Ryan Hill @ 2011-03-17 11:45 UTC (permalink / raw)
To: gcc-patches
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On Wed, 16 Mar 2011 23:51:30 -0700
Benjamin Kosnik <bkoz@redhat.com> wrote:
> Needs some more work, here's a rough draft.
The one I've seen most often other than including cstddef is due to linker
options starting with -- (eg. --export-dynamic, --no-undefined) now being
errors. Previously they were just silently ignored.
The fix of course is to prepend "-Wl," to these flags.
http://gcc.gnu.org/PR46410
--
fonts, gcc-porting, it makes no sense how it makes no sense
toolchain, wxwidgets but i'll take it free anytime
@ gentoo.org EFFD 380E 047A 4B51 D2BD C64F 8AA8 8346 F9A4 0662
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^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [wwwdocs] gcc-4.6/porting_to.html
2011-03-17 6:51 [wwwdocs] gcc-4.6/porting_to.html Benjamin Kosnik
` (2 preceding siblings ...)
2011-03-17 11:45 ` Ryan Hill
@ 2011-03-17 13:59 ` Matthias Klose
2011-10-11 8:18 ` Gerald Pfeifer
4 siblings, 0 replies; 11+ messages in thread
From: Matthias Klose @ 2011-03-17 13:59 UTC (permalink / raw)
To: Benjamin Kosnik; +Cc: gcc-patches
On 17.03.2011 07:51, Benjamin Kosnik wrote:
>
> Needs some more work, here's a rough draft.
>
> -benjamin
+ <p>As a workaround, remove <code>-Werror</code> until the new warnings
+ are fixed, or for conversion warnings
+ add <code>-Wno-unused-but-set-variable</code>
+ or <code>-Wno-unused-but-set-parameter</code>.
+ </p>
what about recommending keeping -Werror and adding
-Wno-error=unused-but-set-variable or -Wno-error=unused-but-set-parameter?
Then the warnings remain, but don't cause an error.
Matthias
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [wwwdocs] gcc-4.6/porting_to.html
2011-03-17 6:51 [wwwdocs] gcc-4.6/porting_to.html Benjamin Kosnik
` (3 preceding siblings ...)
2011-03-17 13:59 ` Matthias Klose
@ 2011-10-11 8:18 ` Gerald Pfeifer
2011-10-11 23:12 ` Benjamin Kosnik
2011-10-24 2:26 ` Gerald Pfeifer
4 siblings, 2 replies; 11+ messages in thread
From: Gerald Pfeifer @ 2011-10-11 8:18 UTC (permalink / raw)
To: Benjamin Kosnik; +Cc: gcc-patches
Hi Benjamin,
On Wed, 16 Mar 2011, Benjamin Kosnik wrote:
> Needs some more work, here's a rough draft.
I realized this one hasn't made it in, but is really nice. I made a
number of minor edits (typos, markup, simplifying headings,... among
others). What do you think -- should we include this?
Many users still won't have GCC 4.6 deployed yet, so I think it's
still worth it.
What do you think?
Gerald
Index: porting_to.html
===================================================================
RCS file: porting_to.html
diff -N porting_to.html
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ porting_to.html 11 Oct 2011 04:47:14 -0000
@@ -0,0 +1,142 @@
+<html>
+
+<head>
+<title>Porting to GCC 4.6</title>
+</head>
+
+<body>
+<h1>Porting to GCC 4.6</h1>
+
+<p>
+The GCC 4.6 release series differs from previous GCC releases in more
+than the usual list of
+<a href="http://gcc.gnu.org/gcc-4.6/changes.html">changes</a>. Some of
+these are a result of bug fixing, and some old behaviors have been
+intentionally changed in order to support new standards, or relaxed
+instandards-conforming ways to facilitate compilation or runtime
+performance. Some of these changes are not visible to the naked eye
+and will not cause problems when updating from older versions.
+</p>
+
+<p>
+However, some of these changes are visible, and can cause grief to
+users porting to GCC 4.6. This document is an effort to identify major
+issues and provide clear solutions in a quick and easily searched
+manner. Additions and suggestions for improvement are welcome.
+</p>
+
+<h2>C language issues</h2>
+
+<h3>New warnings for unused variables and parameters</h3>
+
+<p>
+The behavior of <code>-Wall</code> has changed and now includes the
+new warning flags <code>-Wunused-but-set-variable</code> and
+(with <code>-Wall
+-Wextra</code>) <code>-Wunused-but-set-parameter</code>. This may
+result in new warnings in code that compiled cleanly with previous
+versions of GCC.
+</p>
+
+<p>
+For example,
+<pre>
+ void fn (void)
+ {
+ int foo;
+ foo = bar (); /* foo is never used. */
+ }
+</pre>
+Gives the following diagnostic:
+<pre>
+warning: variable "foo" set but not used [-Wunused-but-set-variable]
+</pre>
+</p>
+low</code> flag
+with <code>-Werror</code> and optimization flags above <code>-O2</code>
+may result in compile errors when using glibc optimizations
+for <code>strcmp</code>.
+</p>
+
+<p>
+For example,
+<pre>
+#include <string.h>
+void do_rm_rf (const char *p) { if (strcmp (p, "/") == 0) return; }
+</pre>
+Results in the following diagnostic:
+<pre>
+error: assuming signed overflow does not occur when changing X +- C1 cmp C2 to X cmp C1 +- C2 [-Werror=strict-overflow]
+</pre>
+</p>
+
+<p>
+To work around this, use <code>-D__NO_STRING_INLINES</code>.
+</p>
+
+<h2>C++ language issues</h2>
+
+<h3>Header dependency changes</h3>
+
+<p>
+Many of the standard C++ library include files have been edited to no
+longer include <cstddef> to get <code>namespace std</code>
+-scoped versions of <code>size_t</code> and <code>ptrdiff_t</code>.
+</p>
+
+<p>
+As such, C++ programs that used the macros <code>NULL</code>
+or <code>offsetof</code> without including <cstddef> will no
+longer compile. The diagnostic produced is similar to:
+</p>
+
+<pre>
+error: 'ptrdiff_t' does not name a type
+</pre>
+
+<pre>
+error: 'size_t' has not been declared
+</pre>
+
+<pre>
+error: 'NULL' was not declared in this scope
+</pre>
+
+<pre>
+error: there are no arguments to 'offsetof' that depend on a template
+parameter, so a declaration of 'offsetof' must be available
+</pre>
+
+<p>
+Fixing this issue is easy: just include <cstddef>.
+</p>
+
+<!--
+<h3>Java issues</h3>
+-->
+
+<h3>Links</h3>
+
+<p>
+Jakub Jelinek,
+ <a href="http://lists.fedoraproject.org/pipermail/devel/2011-February/148523.html">GCC
+4.6 related common package rebuild failures (was Re: mass rebuild status)</a>
+</p>
+
+<p>
+Matthias Klose,
+<a href="http://lists.debian.org/debian-devel-announce/2011/02/msg00012.html">prepare
+to fix build failures with new GCC versions</a>
+</p>
+
+<p>
+Jim Meyering,
+ <a href="http://lists.fedoraproject.org/pipermail/devel/2011-March/149355.html">gcc-4.6.0-0.12.fc15.x86_64 breaks strcmp?</a>
+</p>
+
+<!-- ==================================================================== -->
+
+</body>
+</html>
+
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [wwwdocs] gcc-4.6/porting_to.html
2011-10-11 8:18 ` Gerald Pfeifer
@ 2011-10-11 23:12 ` Benjamin Kosnik
2011-10-13 3:37 ` Gerald Pfeifer
2011-10-24 2:26 ` Gerald Pfeifer
1 sibling, 1 reply; 11+ messages in thread
From: Benjamin Kosnik @ 2011-10-11 23:12 UTC (permalink / raw)
To: Gerald Pfeifer; +Cc: gcc-patches
> I realized this one hasn't made it in, but is really nice. I made a
> number of minor edits (typos, markup, simplifying headings,... among
> others). What do you think -- should we include this?
>
> Many users still won't have GCC 4.6 deployed yet, so I think it's
> still worth it.
>
> What do you think?
Ouch. I see this is not in, and I though I checked in the draft months
ago.
Please check this in immediately!!!
-benjamin
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [wwwdocs] gcc-4.6/porting_to.html
2011-10-11 23:12 ` Benjamin Kosnik
@ 2011-10-13 3:37 ` Gerald Pfeifer
2011-11-20 10:09 ` Gerald Pfeifer
0 siblings, 1 reply; 11+ messages in thread
From: Gerald Pfeifer @ 2011-10-13 3:37 UTC (permalink / raw)
To: Benjamin Kosnik; +Cc: gcc-patches
On Tue, 11 Oct 2011, Benjamin Kosnik wrote:
>> Many users still won't have GCC 4.6 deployed yet, so I think it's
>> still worth it.
> Ouch. I see this is not in, and I though I checked in the draft months
> ago.
>
> Please check this in immediately!!!
Done last evening, and made some further tweaks.
For reference hre is the full patch that's now live on the system.
Gerald
Index: porting_to.html
===================================================================
RCS file: porting_to.html
diff -N porting_to.html
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ porting_to.html 12 Oct 2011 16:16:54 -0000 1.3
@@ -0,0 +1,150 @@
+<html>
+
+<head>
+<title>Porting to GCC 4.6</title>
+</head>
+
+<body>
+<h1>Porting to GCC 4.6</h1>
+
+<p>
+The GCC 4.6 release series differs from previous GCC releases in more
+than the usual list of
+<a href="http://gcc.gnu.org/gcc-4.6/changes.html">changes</a>. Some of
+these are a result of bug fixing, and some old behaviors have been
+intentionally changed in order to support new standards, or relaxed
+instandards-conforming ways to facilitate compilation or runtime
+performance. Some of these changes are not visible to the naked eye
+and will not cause problems when updating from older versions.
+</p>
+
+<p>
+However, some of these changes are visible, and can cause grief to
+users porting to GCC 4.6. This document is an effort to identify major
+issues and provide clear solutions in a quick and easily searched
+manner. Additions and suggestions for improvement are welcome.
+</p>
+
+<h2>C language issues</h2>
+
+<h3>New warnings for unused variables and parameters</h3>
+
+<p>
+The behavior of <code>-Wall</code> has changed and now includes the
+new warning flags <code>-Wunused-but-set-variable</code> and
+(with <code>-Wall
+-Wextra</code>) <code>-Wunused-but-set-parameter</code>. This may
+result in new warnings in code that compiled cleanly with previous
+versions of GCC.
+</p>
+
+<p>For example,</p>
+<pre>
+ void fn (void)
+ {
+ int foo;
+ foo = bar (); /* foo is never used. */
+ }
+</pre>
+<p>Gives the following diagnostic:</p>
+<pre>
+warning: variable "foo" set but not used [-Wunused-but-set-variable]
+</pre>
+
+<p>Although these warnings will not result in compilation failure,
+often <code>-Wall</code> is used in conjunction with
+<code>-Werror</code> and as a result, new warnings are turned into
+new errors.</p>
+
+<p>To fix, first see if the unused variable or parameter can be removed
+without changing the result or logic of the surrounding code. If not,
+annotate it with <code>__attribute__((__unused__))</code>.</p>
+
+<p>As a workaround, remove <code>-Werror</code> until the new warnings
+are fixed. For conversion warnings add
+<code>-Wno-unused-but-set-variable</code> or
+<code>-Wno-unused-but-set-parameter</code>.</p>
+
+<h3>Strict overflow warnings</h3>
+
+<p>Using the <code>-Wstrict-overflow</code> flag with
+<code>-Werror</code> and optmization flags above <code>-O2</code>
+may result in compile errors when using glibc optimizations
+for <code>strcmp</code>.</p>
+
+<p>For example,</p>
+<pre>
+#include <string.h>
+void do_rm_rf (const char *p) { if (strcmp (p, "/") == 0) return; }
+</pre>
+<p>Results in the following diagnostic:</p>
+<pre>
+error: assuming signed overflow does not occur when changing X +- C1 cmp C2 to X cmp C1 +- C2 [-Werror=strict-overflow]
+</pre>
+
+<p>To work around this, use <code>-D__NO_STRING_INLINES</code>.</p>
+
+<h2>C++ language issues</h2>
+
+<h3>Header dependency changes</h3>
+
+<p>
+Many of the standard C++ library include files have been edited to no
+longer include <cstddef> to get <code>namespace std</code>
+-scoped versions of <code>size_t</code> and <code>ptrdiff_t</code>.
+</p>
+
+<p>
+As such, C++ programs that used the macros <code>NULL</code>
+or <code>offsetof</code> without including <cstddef> will no
+longer compile. The diagnostic produced is similar to:
+</p>
+
+<pre>
+error: 'ptrdiff_t' does not name a type
+</pre>
+
+<pre>
+error: 'size_t' has not been declared
+</pre>
+
+<pre>
+error: 'NULL' was not declared in this scope
+</pre>
+
+<pre>
+error: there are no arguments to 'offsetof' that depend on a template
+parameter, so a declaration of 'offsetof' must be available
+</pre>
+
+<p>
+Fixing this issue is easy: just include <cstddef>.
+</p>
+
+<!--
+<h3>Java issues</h3>
+-->
+
+<h3>Links</h3>
+
+<p>
+Jakub Jelinek,
+ <a href="http://lists.fedoraproject.org/pipermail/devel/2011-February/148523.html">GCC
+4.6 related common package rebuild failures (was Re: mass rebuild status)</a>
+</p>
+
+<p>
+Matthias Klose,
+<a href="http://lists.debian.org/debian-devel-announce/2011/02/msg00012.html">prepare
+to fix build failures with new GCC versions</a>
+</p>
+
+<p>
+Jim Meyering,
+ <a href="http://lists.fedoraproject.org/pipermail/devel/2011-March/149355.html">gcc-4.6.0-0.12.fc15.x86_64 breaks strcmp?</a>
+</p>
+
+</body>
+</html>
+
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [wwwdocs] gcc-4.6/porting_to.html
2011-10-11 8:18 ` Gerald Pfeifer
2011-10-11 23:12 ` Benjamin Kosnik
@ 2011-10-24 2:26 ` Gerald Pfeifer
2011-11-15 16:40 ` Richard Sandiford
1 sibling, 1 reply; 11+ messages in thread
From: Gerald Pfeifer @ 2011-10-24 2:26 UTC (permalink / raw)
To: Benjamin Kosnik, gcc-patches; +Cc: Jakub Jelinek
On Mon, 10 Oct 2011, Gerald Pfeifer wrote:
> I realized this one hasn't made it in, but is really nice. I made a
> number of minor edits (typos, markup, simplifying headings,... among
> others). What do you think -- should we include this?
Checking mailing list archives I realized that Jakub had provided
feedback ( http://gcc.gnu.org/ml/gcc-patches/2011-03/msg00987.html )
that the strict overflow warnings had been fixed.
Hence I went ahead and committed the removal below.
Gerald
Index: porting_to.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-4.6/porting_to.html,v
retrieving revision 1.3
diff -u -r1.3 porting_to.html
--- porting_to.html 12 Oct 2011 16:16:54 -0000 1.3
+++ porting_to.html 24 Oct 2011 00:52:53 -0000
@@ -65,24 +65,6 @@
<code>-Wno-unused-but-set-variable</code> or
<code>-Wno-unused-but-set-parameter</code>.</p>
-<h3>Strict overflow warnings</h3>
-
-<p>Using the <code>-Wstrict-overflow</code> flag with
-<code>-Werror</code> and optmization flags above <code>-O2</code>
-may result in compile errors when using glibc optimizations
-for <code>strcmp</code>.</p>
-
-<p>For example,</p>
-<pre>
-#include <string.h>
-void do_rm_rf (const char *p) { if (strcmp (p, "/") == 0) return; }
-</pre>
-<p>Results in the following diagnostic:</p>
-<pre>
-error: assuming signed overflow does not occur when changing X +- C1 cmp C2 to X cmp C1 +- C2 [-Werror=strict-overflow]
-</pre>
-
-<p>To work around this, use <code>-D__NO_STRING_INLINES</code>.</p>
<h2>C++ language issues</h2>
@@ -139,11 +121,6 @@
to fix build failures with new GCC versions</a>
</p>
-<p>
-Jim Meyering,
- <a href="http://lists.fedoraproject.org/pipermail/devel/2011-March/149355.html">gcc-4.6.0-0.12.fc15.x86_64 breaks strcmp?</a>
-</p>
-
</body>
</html>
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [wwwdocs] gcc-4.6/porting_to.html
2011-10-24 2:26 ` Gerald Pfeifer
@ 2011-11-15 16:40 ` Richard Sandiford
0 siblings, 0 replies; 11+ messages in thread
From: Richard Sandiford @ 2011-11-15 16:40 UTC (permalink / raw)
To: Gerald Pfeifer; +Cc: Benjamin Kosnik, gcc-patches, Jakub Jelinek
[Sorry for the delay, catching up after being away]
Gerald Pfeifer <gerald@pfeifer.com> writes:
> On Mon, 10 Oct 2011, Gerald Pfeifer wrote:
>> I realized this one hasn't made it in, but is really nice. I made a
>> number of minor edits (typos, markup, simplifying headings,... among
>> others). What do you think -- should we include this?
>
> Checking mailing list archives I realized that Jakub had provided
> feedback ( http://gcc.gnu.org/ml/gcc-patches/2011-03/msg00987.html )
> that the strict overflow warnings had been fixed.
>
> Hence I went ahead and committed the removal below.
Thanks for doing this. I noticed a typo while reading it, so I committed
the patch below as obvious.
Richard
Index: porting_to.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-4.6/porting_to.html,v
retrieving revision 1.4
diff -u -r1.4 porting_to.html
--- porting_to.html 24 Oct 2011 00:57:54 -0000 1.4
+++ porting_to.html 15 Nov 2011 13:38:10 -0000
@@ -13,7 +13,7 @@
<a href="http://gcc.gnu.org/gcc-4.6/changes.html">changes</a>. Some of
these are a result of bug fixing, and some old behaviors have been
intentionally changed in order to support new standards, or relaxed
-instandards-conforming ways to facilitate compilation or runtime
+in standards-conforming ways to facilitate compilation or runtime
performance. Some of these changes are not visible to the naked eye
and will not cause problems when updating from older versions.
</p>
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [wwwdocs] gcc-4.6/porting_to.html
2011-10-13 3:37 ` Gerald Pfeifer
@ 2011-11-20 10:09 ` Gerald Pfeifer
0 siblings, 0 replies; 11+ messages in thread
From: Gerald Pfeifer @ 2011-11-20 10:09 UTC (permalink / raw)
To: gcc-patches, Benjamin Kosnik; +Cc: Matthias Klose
On Wed, 12 Oct 2011, Gerald Pfeifer wrote:
> For reference hre is the full patch that's now live on the system.
And this take into account a suggestion by Matthias Klose
(cf. http://gcc.gnu.org/ml/gcc-patches/2011-03/msg01014.html ).
Applied.
Gerald
Index: porting_to.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-4.6/porting_to.html,v
retrieving revision 1.5
diff -u -r1.5 porting_to.html
--- porting_to.html 15 Nov 2011 13:38:24 -0000 1.5
+++ porting_to.html 19 Nov 2011 16:56:39 -0000
@@ -60,10 +60,9 @@
without changing the result or logic of the surrounding code. If not,
annotate it with <code>__attribute__((__unused__))</code>.</p>
-<p>As a workaround, remove <code>-Werror</code> until the new warnings
-are fixed. For conversion warnings add
-<code>-Wno-unused-but-set-variable</code> or
-<code>-Wno-unused-but-set-parameter</code>.</p>
+<p>As a workaround, add
+<code>-Wno-error=unused-but-set-variable</code> or
+<code>-Wno-error=unused-but-set-parameter</code>.</p>
<h2>C++ language issues</h2>
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2011-11-20 2:03 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-03-17 6:51 [wwwdocs] gcc-4.6/porting_to.html Benjamin Kosnik
2011-03-17 7:59 ` Hans-Peter Nilsson
2011-03-17 8:11 ` Jakub Jelinek
2011-03-17 11:45 ` Ryan Hill
2011-03-17 13:59 ` Matthias Klose
2011-10-11 8:18 ` Gerald Pfeifer
2011-10-11 23:12 ` Benjamin Kosnik
2011-10-13 3:37 ` Gerald Pfeifer
2011-11-20 10:09 ` Gerald Pfeifer
2011-10-24 2:26 ` Gerald Pfeifer
2011-11-15 16:40 ` Richard Sandiford
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