code review 11606043: cmd/gc, cmd/ld: fix build: remove unused var, use corre...

cmd/gc, cmd/ld: fix build: remove unused var, use correct var in printf

Fixes issue 5924.

[iant, 2013-07-19 20:25:34]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://go.googlecode.com/hg/

[khr1, 2013-07-19 20:29:40]

LGTM


On Fri, Jul 19, 2013 at 1:25 PM, <iant@golang.org> wrote:

> Reviewers: golang-dev1,
>
> Message:
> Hello golang-dev@googlegroups.com,
>
> I'd like you to review this change to
> https://go.googlecode.com/hg/
>
>
> Description:
> cmd/gc, cmd/ld: fix build: remove unused var, use correct var in printf
>
> Please review this at
https://codereview.appspot.**com/11606043/<https://codereview.appspot.com/116...
>
> Affected files:
>   M src/cmd/gc/pgen.c
>   M src/cmd/ld/lib.c
>
>
> Index: src/cmd/gc/pgen.c
> ==============================**==============================**=======
> --- a/src/cmd/gc/pgen.c
> +++ b/src/cmd/gc/pgen.c
> @@ -17,7 +17,7 @@
>  {
>         Plist *pl;
>         Node nod1, *n, *gcnod;
> -       Prog *pfuncdata, *ptxt, *p, *p1;
> +       Prog *ptxt, *p, *p1;
>         int32 lno;
>         Type *t;
>         Iter save;
> @@ -99,7 +99,7 @@
>         gcnod->class = PEXTERN;
>
>         nodconst(&nod1, types[TINT32], FUNCDATA_GC);
> -       pfuncdata = gins(AFUNCDATA, &nod1, gcnod);
> +       gins(AFUNCDATA, &nod1, gcnod);
>
>         for(t=curfn->paramfld; t; t=t->down)
>                 gtrack(tracksym(t->type));
> Index: src/cmd/ld/lib.c
> ==============================**==============================**=======
> --- a/src/cmd/ld/lib.c
> +++ b/src/cmd/ld/lib.c
> @@ -2458,7 +2458,7 @@
>                 for(p = cursym->text; p != P; p = p->link) {
>                         if(p->as == AFUNCDATA) {
>                                 if((havefunc[p->from.offset/**
> 32]>>(p->from.offset%32))&1)
> -                                       diag("multiple definitions for
> FUNCDATA $%d", i);
> +                                       diag("multiple definitions for
> FUNCDATA $%d", p->from.offset);
>                                 havefunc[p->from.offset/32] |=
> 1<<(p->from.offset%32);
>                         }
>                         if(p->as == APCDATA)
>
>
> --
>
> ---You received this message because you are subscribed to the Google
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> To unsubscribe from this group and stop receiving emails from it, send an
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> .
>
>
>

[rsc, 2013-07-19 20:45:45]

I apologize for using gcc on Mac, from which Apple has removed all the
useful warnings.

Russ

[iant, 2013-07-19 22:04:56]

*** Submitted as https://code.google.com/p/go/source/detail?r=fe3232662436 ***

cmd/gc, cmd/ld: fix build: remove unused var, use correct var in printf

Fixes issue 5924.

R=golang-dev, khr, rsc
CC=golang-dev
https://codereview.appspot.com/11606043

[rsc, 2013-07-19 22:47:36]

You can build Go with clang by running

CC=clang all.bash

Unfortunately, clang appears not to warn about unused variables either.

Russ

[dave_cheney.net, 2013-07-19 22:58:49]

I use this small change to cmd/dist to enable the warning

https://codereview.appspot.com/8090044/

I have had reports that this behaviour is the default in the OS X 10.9
prerelease.

On Sat, Jul 20, 2013 at 8:47 AM, Russ Cox <rsc@golang.org> wrote:
> You can build Go with clang by running
>
> CC=clang all.bash
>
> Unfortunately, clang appears not to warn about unused variables either.
>
> Russ
>
> --
>
> ---
> You received this message because you are subscribed to the Google Groups
> "golang-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to golang-dev+unsubscribe@googlegroups.com.
> For more options, visit https://groups.google.com/groups/opt_out.
>
>

[dvyukov, 2013-07-20 12:34:50]

If clang produces not enough warnings for your taste, try --analyze
-fsanitize=undefined:

src/lib9/flag.c:268:7: warning: Access to field 'iscount' results in a
dereference of a null pointer

      (loaded from variable 'f')

src/lib9/fmt/fmtquote.c:58:8: warning: Dereference of null pointer
(loaded from variable 'r')

/usr/bin/ranlib: warning for library: pkg/obj/darwin_amd64/lib9.a the
table of contents is empty (no object file members in the library
define global symbols)

libbio

/usr/bin/ranlib: warning for library: pkg/obj/darwin_amd64/libbio.a
the table of contents is empty (no object file members in the library
define global symbols)

libmach

src/libmach/obj.c:298:13: warning: Dereference of null pointer

src/libmach/sym.c:580:4: warning: Access to field 'hist' results in a
dereference of a null pointer

      (loaded from variable 'f')

src/libmach/sym.c:1087:11: warning: Memory is never released;
potential leak of memory pointed to by

      'dest'

/usr/bin/ranlib: warning for library: pkg/obj/darwin_amd64/libmach.a
the table of contents is empty (no object file members in the library
define global symbols)

misc/pprof

cmd/addr2line

cmd/nm

src/cmd/nm/nm.c:139:4: warning: Address of stack memory associated
with local variable 'name' is still

      referred to by the global variable 'filename' upon returning to
the caller. This will be a dangling reference

src/cmd/nm/nm.c:146:5: warning: Address of stack memory associated
with local variable 'name' is still

      referred to by the global variable 'filename' upon returning to
the caller. This will be a dangling reference

src/cmd/nm/nm.c:161:1: warning: Address of stack memory associated
with local variable 'name' is still

      referred to by the global variable 'filename' upon returning to
the caller. This will be a dangling reference

....



src/cmd/gc/obj.c:310:3: runtime error: index 9 out of bounds for type 'char
[3]'

src/cmd/gc/esc.c:252:20: runtime error: index 4 out of bounds for type
'char [3]'

src/cmd/gc/obj.c:310:3: runtime error: index 11 out of bounds for type
'char [3]'

src/cmd/6g/gsubr.c:543:29: runtime error: left shift of negative value -1

src/cmd/6c/sgen.c:39:17: runtime error: left shift of 2147483648 by 32
places cannot be represented in type 'vlong' (aka 'long long')

src/cmd/cc/com.c:1330:24: runtime error: left shift of 1 by 63 places
cannot be represented in type 'long long'

src/cmd/6c/sgen.c:39:17: runtime error: left shift of 2147483648 by 32
places cannot be represented in type 'vlong' (aka 'long long')

src/cmd/6a/../cc/lexbody:258:10: runtime error: signed integer
overflow: 1477718474 + 738859237 cannot be represented in type 'int'

src/cmd/6a/../cc/lexbody:258:8: runtime error: signed integer
overflow: -2078389490 + -2078389490 cannot be represented in type
'int'

src/cmd/6a/../cc/lexbody:258:10: runtime error: signed integer
overflow: 1572441972 + 786220986 cannot be represented in type 'int'

src/cmd/6a/../cc/lexbody:258:8: runtime error: signed integer
overflow: -1936048415 + -1936048415 cannot be represented in type
'int'

src/cmd/gc/subr.c:333:8: runtime error: signed integer overflow:
805000852 * 3 cannot be represented in type 'int'

src/cmd/6g/gsubr.c:543:29: runtime error: left shift of negative value -1

.....

[dave_cheney.net, 2013-07-20 12:37:43]

Related: https://code.google.com/p/go/issues/detail?id=5764

On Sat, Jul 20, 2013 at 10:34 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> If clang produces not enough warnings for your taste, try --analyze
> -fsanitize=undefined:
>
> src/lib9/flag.c:268:7: warning: Access to field 'iscount' results in a
> dereference of a null pointer
>
>       (loaded from variable 'f')
>
> src/lib9/fmt/fmtquote.c:58:8: warning: Dereference of null pointer
> (loaded from variable 'r')
>
> /usr/bin/ranlib: warning for library: pkg/obj/darwin_amd64/lib9.a the
> table of contents is empty (no object file members in the library
> define global symbols)
>
> libbio
>
> /usr/bin/ranlib: warning for library: pkg/obj/darwin_amd64/libbio.a
> the table of contents is empty (no object file members in the library
> define global symbols)
>
> libmach
>
> src/libmach/obj.c:298:13: warning: Dereference of null pointer
>
> src/libmach/sym.c:580:4: warning: Access to field 'hist' results in a
> dereference of a null pointer
>
>       (loaded from variable 'f')
>
> src/libmach/sym.c:1087:11: warning: Memory is never released;
> potential leak of memory pointed to by
>
>       'dest'
>
> /usr/bin/ranlib: warning for library: pkg/obj/darwin_amd64/libmach.a
> the table of contents is empty (no object file members in the library
> define global symbols)
>
> misc/pprof
>
> cmd/addr2line
>
> cmd/nm
>
> src/cmd/nm/nm.c:139:4: warning: Address of stack memory associated
> with local variable 'name' is still
>
>       referred to by the global variable 'filename' upon returning to
> the caller. This will be a dangling reference
>
> src/cmd/nm/nm.c:146:5: warning: Address of stack memory associated
> with local variable 'name' is still
>
>       referred to by the global variable 'filename' upon returning to
> the caller. This will be a dangling reference
>
> src/cmd/nm/nm.c:161:1: warning: Address of stack memory associated
> with local variable 'name' is still
>
>       referred to by the global variable 'filename' upon returning to
> the caller. This will be a dangling reference
>
> ....
>
>
>
> src/cmd/gc/obj.c:310:3: runtime error: index 9 out of bounds for type 'char
[3]'
>
> src/cmd/gc/esc.c:252:20: runtime error: index 4 out of bounds for type
> 'char [3]'
>
> src/cmd/gc/obj.c:310:3: runtime error: index 11 out of bounds for type
> 'char [3]'
>
> src/cmd/6g/gsubr.c:543:29: runtime error: left shift of negative value -1
>
> src/cmd/6c/sgen.c:39:17: runtime error: left shift of 2147483648 by 32
> places cannot be represented in type 'vlong' (aka 'long long')
>
> src/cmd/cc/com.c:1330:24: runtime error: left shift of 1 by 63 places
> cannot be represented in type 'long long'
>
> src/cmd/6c/sgen.c:39:17: runtime error: left shift of 2147483648 by 32
> places cannot be represented in type 'vlong' (aka 'long long')
>
> src/cmd/6a/../cc/lexbody:258:10: runtime error: signed integer
> overflow: 1477718474 + 738859237 cannot be represented in type 'int'
>
> src/cmd/6a/../cc/lexbody:258:8: runtime error: signed integer
> overflow: -2078389490 + -2078389490 cannot be represented in type
> 'int'
>
> src/cmd/6a/../cc/lexbody:258:10: runtime error: signed integer
> overflow: 1572441972 + 786220986 cannot be represented in type 'int'
>
> src/cmd/6a/../cc/lexbody:258:8: runtime error: signed integer
> overflow: -1936048415 + -1936048415 cannot be represented in type
> 'int'
>
> src/cmd/gc/subr.c:333:8: runtime error: signed integer overflow:
> 805000852 * 3 cannot be represented in type 'int'
>
> src/cmd/6g/gsubr.c:543:29: runtime error: left shift of negative value -1
>
> .....

[ality, 2013-07-20 14:32:26]

Dmitry Vyukov <dvyukov@google.com> once said:
> If clang produces not enough warnings for your taste, try --analyze
> -fsanitize=undefined:
>
> [snip]

I looked at a dozen of these and they were all false positives.
Is there any way to dial it down? Or was this sarcasm? ☺

  Anthony