Re: [PATCH] add attribute none to pthread_setspecific (BZ #27714)

[Martin Sebor <msebor@gmail.com>]

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On 4/27/21 3:58 PM, Joseph Myers wrote:
> On Tue, 27 Apr 2021, Martin Sebor via Libc-alpha wrote:
> 
>> These are warnings in my build (I've seen a few others scroll by
>> and have always assumed they were expected(*)).  Those you pasted
> 
> Most warnings are errors by default (unless you use --disable-werror,
> which should never normally be used in glibc development unless you're
> e.g. reviewing the warnings you get if you add extra warning options to
> those with which glibc is built by default, in order to fix those warnings
> before adding the extra options).

Ah, that's what my build script does and I keep forgetting to
change that when working on Glibc (as opposed to testing new
GCC warnings).  My bad.  The attached diff patches up the tests
to pass the function a valid argument.  I'll plan to commit it
shortly unless you prefer some other solution.

Martin

> 
>> I test by simply running make check.  I can make the change to
>> the test if you expect warning-free test builds.
> 
> We expect builds, for all glibc ABIs, free from compile errors or failures
> of tests that can run without needing to execute any code for the glibc
> architecture.  That means no warnings that are turned into errors by
> -Werror.  There are some warnings for which -Wno-error or pragmas are used
> to stop them being errors; all other warnings are disallowed.
> 
>> [*] Here's an example of a warning I just noticed while rerunning
>> make check:
>>
>> tst-chk1.c: In function ‘do_test’:
> 
> That's an example covered by -Wno-error.
> 
> # We know these tests have problems with format strings, this is what
> # we are testing.  Disable that warning.  They are also testing
> # deprecated functions (notably gets) so disable that warning as well.
> # And they also generate warnings from warning attributes, which
> # cannot be disabled via pragmas, so require -Wno-error to be used.
> CFLAGS-tst-chk1.c += -Wno-format -Wno-deprecated-declarations -Wno-error
> 
> (Any code disabling any warnings or disabling -Werror for them is expected
> to have a comment explaining why it's OK to do so in that case.)
> 


[-- Attachment #2: glibc-tests-pthread_setspecific.diff --]
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diff --git a/nptl/tst-tsd3.c b/nptl/tst-tsd3.c
index 0dd39ccb2b..45c7e4e1ea 100644
--- a/nptl/tst-tsd3.c
+++ b/nptl/tst-tsd3.c
@@ -37,7 +37,8 @@ destr1 (void *arg)
     {
       puts ("set key2");
 
-      if (pthread_setspecific (key2, (void *) 1l) != 0)
+      /* Use an arbirary but valid pointer to avoid GCC warnings.  */
+      if (pthread_setspecific (key2, (void *) &left) != 0)
 	{
 	  puts ("destr1: setspecific failed");
 	  exit (1);
@@ -53,7 +54,8 @@ destr2 (void *arg)
     {
       puts ("set key1");
 
-      if (pthread_setspecific (key1, (void *) 1l) != 0)
+      /* Use an arbirary but valid pointer to avoid GCC warnings.  */
+      if (pthread_setspecific (key1, (void *) &left) != 0)
 	{
 	  puts ("destr2: setspecific failed");
 	  exit (1);
@@ -68,8 +70,9 @@ tf (void *arg)
   /* Let the destructors work.  */
   left = 7;
 
-  if (pthread_setspecific (key1, (void *) 1l) != 0
-      || pthread_setspecific (key2, (void *) 1l) != 0)
+  /* Use an arbirary but valid pointer to avoid GCC warnings.  */
+  if (pthread_setspecific (key1, (void *) &left) != 0
+      || pthread_setspecific (key2, (void *) &left) != 0)
     {
       puts ("tf: setspecific failed");
       exit (1);
diff --git a/nptl/tst-tsd4.c b/nptl/tst-tsd4.c
index cc1ada4d4d..f45cf70e37 100644
--- a/nptl/tst-tsd4.c
+++ b/nptl/tst-tsd4.c
@@ -34,7 +34,8 @@ destr (void *arg)
 {
   ++rounds;
 
-  if (pthread_setspecific (key, (void *) 1l) != 0)
+  /* Use an arbirary but valid pointer to avoid GCC warnings.  */
+  if (pthread_setspecific (key, (void *) &rounds) != 0)
     {
       puts ("destr: setspecific failed");
       exit (1);
@@ -45,7 +46,7 @@ destr (void *arg)
 static void *
 tf (void *arg)
 {
-  if (pthread_setspecific (key, (void *) 1l) != 0)
+  if (pthread_setspecific (key, (void *) &rounds) != 0)
     {
       puts ("tf: setspecific failed");
       exit (1);
diff --git a/sysdeps/pthread/tst-key2.c b/sysdeps/pthread/tst-key2.c
index 6828873e41..5662842035 100644
--- a/sysdeps/pthread/tst-key2.c
+++ b/sysdeps/pthread/tst-key2.c
@@ -56,7 +56,7 @@ tf (void *arg)
 {
   pthread_key_t *key = (pthread_key_t *) arg;
 
-  if (pthread_setspecific (*key, (void *) -1l) != 0)
+  if (pthread_setspecific (*key, (void *) arg) != 0)
     {
       write_message ("setspecific failed\n");
       _exit (1);