Re: [PATCH] elfcmp: fix self-comparison error with GCC 6

Re: [PATCH] elfcmp: fix self-comparison error with GCC 6

[Mark Wielaard]

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On Mon, 2016-04-11 at 16:00 +0200, david.abdurachmanov(a)cern.ch wrote:
> From: David Abdurachmanov <davidlt@cern.ch>
> 
> Noticed with Fedora 24 Alpha, gcc (GCC) 6.0.0 20160406
> (Red Hat 6.0.0-0.20).
> 
> elfcmp.c: In function ‘main’:
> elfcmp.c:364:199: error: self-comparison always evaluates
> to false [-Werror=tautological-compare]
>         if (unlikely (name1 == NULL || name2 == NULL
> @@ -368,7 +368,7 @@ main (int argc, char *argv[])
>  				&& sym1->st_shndx != SHN_UNDEF)
>  			    || sym1->st_info != sym2->st_info
>  			    || sym1->st_other != sym2->st_other
> -			    || sym1->st_shndx != sym1->st_shndx))
> +			    || sym1->st_shndx != sym2->st_shndx))
>  		{
>  		  // XXX Do we want to allow reordered symbol tables?
>  		symtab_mismatch:

Thanks! And oops. Applied since that was obviously wrong.

Nice that GCC caught that. I am slightly surprised my own GCC6 testing
didn't find this. I am using upstream gcc (GCC) 6.0.0 20160410
(experimental). Did you have to do anything special on your Fedora setup
to make GCC detect this?

Thanks,

Mark

Re: [PATCH] elfcmp: fix self-comparison error with GCC 6

[David Abdurachmanov]

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> On 11 Apr 2016, at 17:13, Mark Wielaard <mjw@redhat.com> wrote:
> 
> Nice that GCC caught that. I am slightly surprised my own GCC6 testing
> didn't find this. I am using upstream gcc (GCC) 6.0.0 20160410
> (experimental). Did you have to do anything special on your Fedora setup
> to make GCC detect this?

Nothing, usual morning procedure: dnf upgrade && reboot

There was an update to GCC maybe 1 or 2 days ago. Maybe some improvements
with that came in.

david

[PATCH] elfcmp: fix self-comparison error with GCC 6

[david.abdurachmanov]

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From: David Abdurachmanov <davidlt@cern.ch>

Noticed with Fedora 24 Alpha, gcc (GCC) 6.0.0 20160406
(Red Hat 6.0.0-0.20).

elfcmp.c: In function ‘main’:
elfcmp.c:364:199: error: self-comparison always evaluates
to false [-Werror=tautological-compare]
        if (unlikely (name1 == NULL || name2 == NULL

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
---
 src/ChangeLog | 4 ++++
 src/elfcmp.c  | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/ChangeLog b/src/ChangeLog
index f74b5dc..bdc9d13 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2016-04-11  David Abdurachmanov  <davidlt@cern.ch>
+
+	* elfcmp.c (main): Fix self-comparison error with GCC 6.
+
 2016-03-21  Mark Wielaard  <mjw@redhat.com>
 
 	* nm.c (show_symbols): Check for malloc size argument overflow.
diff --git a/src/elfcmp.c b/src/elfcmp.c
index 852b92f..7b5d39c 100644
--- a/src/elfcmp.c
+++ b/src/elfcmp.c
@@ -368,7 +368,7 @@ main (int argc, char *argv[])
 				&& sym1->st_shndx != SHN_UNDEF)
 			    || sym1->st_info != sym2->st_info
 			    || sym1->st_other != sym2->st_other
-			    || sym1->st_shndx != sym1->st_shndx))
+			    || sym1->st_shndx != sym2->st_shndx))
 		{
 		  // XXX Do we want to allow reordered symbol tables?
 		symtab_mismatch:
-- 
2.7.3

[PATCH] elfcmp: fix self-comparison error with GCC 6

[david.abdurachmanov]

[-- Attachment #1: Type: text/plain, Size: 1328 bytes --]

From: David Abdurachmanov <davidlt@cern.ch>

Noticed with Fedora 24 Alpha, gcc (GCC) 6.0.0 20160406
(Red Hat 6.0.0-0.20).

elfcmp.c: In function ‘main’:
elfcmp.c:364:199: error: self-comparison always evaluates
to false [-Werror=tautological-compare]
        if (unlikely (name1 == NULL || name2 == NULL

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
---
 src/ChangeLog | 4 ++++
 src/elfcmp.c  | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/ChangeLog b/src/ChangeLog
index f74b5dc..bdc9d13 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2016-04-11  David Abdurachmanov  <davidlt@cern.ch>
+
+	* elfcmp.c (main): Fix self-comparison error with GCC 6.
+
 2016-03-21  Mark Wielaard  <mjw@redhat.com>
 
 	* nm.c (show_symbols): Check for malloc size argument overflow.
diff --git a/src/elfcmp.c b/src/elfcmp.c
index 852b92f..7b5d39c 100644
--- a/src/elfcmp.c
+++ b/src/elfcmp.c
@@ -368,7 +368,7 @@ main (int argc, char *argv[])
 				&& sym1->st_shndx != SHN_UNDEF)
 			    || sym1->st_info != sym2->st_info
 			    || sym1->st_other != sym2->st_other
-			    || sym1->st_shndx != sym1->st_shndx))
+			    || sym1->st_shndx != sym2->st_shndx))
 		{
 		  // XXX Do we want to allow reordered symbol tables?
 		symtab_mismatch:
-- 
2.7.3