Fix #1424, api warning listInterfaces #1428

paulober · 2022-09-08T09:09:30Z

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yubiuser · 2022-09-08T09:33:19Z

Pi-hole enforces DCO. Please sign-off your commit.

https://docs.pi-hole.net/guides/github/how-to-signoff/

DL6ER · 2022-09-08T10:41:53Z

Please submit all pull requests against the development branch. Failure to do so will delay or deny your request

I changed the target branch for you.

Is this the only issue gcc-12 found? Does compilation succeed on your system on this branch? I'm just trying to avoid many bits-and-pieces pull requests.

paulober · 2022-09-08T17:49:29Z

I also got this error message on build with gcc 12.1.1 20220730:

[ 45%] Building C object src/dnsmasq/CMakeFiles/dnsmasq.dir/domain-match.c.o
/home/paul/FTL/src/args.c: In Funktion »cli_tick«:
/home/paul/FTL/src/args.c:413:37: Error: Function could be a candidate for attribute »pure« [-Werror=suggest-attribute=pure]
  413 | const char __attribute__ ((const)) *cli_tick(void)
      |                                     ^~~~~~~~
/home/paul/FTL/src/args.c: In Funktion »cli_cross«:
/home/paul/FTL/src/args.c:419:37: Error: Function could be a candidate for attribute »pure« [-Werror=suggest-attribute=pure]
  419 | const char __attribute__ ((const)) *cli_cross(void)
      |                                     ^~~~~~~~~
/home/paul/FTL/src/args.c: In Funktion »cli_info«:
/home/paul/FTL/src/args.c:425:37: Error: Function could be a candidate for attribute »pure« [-Werror=suggest-attribute=pure]
  425 | const char __attribute__ ((const)) *cli_info(void)
      |                                     ^~~~~~~~
/home/paul/FTL/src/args.c: In Funktion »cli_done«:
/home/paul/FTL/src/args.c:437:37: Error: Function could be a candidate for attribute »pure« [-Werror=suggest-attribute=pure]
  437 | const char __attribute__ ((const)) *cli_done(void)
      |                                     ^~~~~~~~
/home/paul/FTL/src/args.c: In Funktion »cli_bold«:
/home/paul/FTL/src/args.c:443:37: Error: Function could be a candidate for attribute »pure« [-Werror=suggest-attribute=pure]
  443 | const char __attribute__ ((const)) *cli_bold(void)
      |                                     ^~~~~~~~
/home/paul/FTL/src/args.c: In Funktion »cli_normal«:
/home/paul/FTL/src/args.c:449:37: Error: Function could be a candidate for attribute »pure« [-Werror=suggest-attribute=pure]
  449 | const char __attribute__ ((const)) *cli_normal(void)
      |                                     ^~~~~~~~~~
cc1: All warnings are treated as errors
make[2]: *** [src/CMakeFiles/FTL.dir/build.make:76: src/CMakeFiles/FTL.dir/args.c.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:237: src/CMakeFiles/FTL.dir/all] Error 2

paulober · 2022-09-08T17:49:57Z

I changed the target branch for you.

And thanks for changeing it

paulober · 2022-09-08T17:56:59Z

Found this thread on this: https://stackoverflow.com/questions/41712635/gcc-error-function-might-be-candidate-for-attribute-pure-if-it-is-known-to-re

DL6ER · 2022-09-09T01:54:08Z

The GCC documentation clearly states:

The const attribute imposes greater restrictions on a function’s definition than the similar pure attribute.

Please try __attribute__ ((const,pure)) and see if the error goes away. This would be kind of an ugly workaround but it seems worth trying. I'm on a business trip and will only return tomorrow evening so I cannot do any real testing from my side right now

gcc 12.1.1 optimization Signed-off-by: paulober <44974737+paulober@users.noreply.github.com>

paulober · 2022-09-09T09:06:36Z

Does not work:

[ 45%] Building C object src/dnsmasq/CMakeFiles/dnsmasq.dir/domain-match.c.o
/home/paul/FTL/src/tre-regex/xmalloc.c: In Funktion »xrealloc_impl«:
/home/paul/FTL/src/tre-regex/xmalloc.c:343:7: Warning: pointer "ptr" may be used after "realloc" [-Wuse-after-free]
  343 |       hash_table_del(xmalloc_table, ptr);
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/paul/FTL/src/tre-regex/xmalloc.c:340:13: Anmerkung: »realloc« wird hier aufgerufen
  340 |   new_ptr = realloc(ptr, new_size);
      |             ^~~~~~~~~~~~~~~~~~~~~~
[ 45%] Built target tre-regex
[ 45%] Building C object src/CMakeFiles/FTL.dir/args.c.o
/home/paul/FTL/src/args.c:414:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  414 | {
      | ^
In Datei, eingebunden von /home/paul/FTL/src/args.c:17:
/home/paul/FTL/src/args.h:19:13: Note: previous declaration here
   19 | const char *cli_tick(void) __attribute__ ((const));
      |             ^~~~~~~~
/home/paul/FTL/src/args.c:414:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  414 | {
      | ^
/home/paul/FTL/src/args.h:19:13: Note: previous declaration here
   19 | const char *cli_tick(void) __attribute__ ((const));
      |             ^~~~~~~~
/home/paul/FTL/src/args.c:420:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  420 | {
      | ^
/home/paul/FTL/src/args.h:20:13: Note: previous declaration here
   20 | const char *cli_cross(void) __attribute__ ((const));
      |             ^~~~~~~~~
/home/paul/FTL/src/args.c:420:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  420 | {
      | ^
/home/paul/FTL/src/args.h:20:13: Note: previous declaration here
   20 | const char *cli_cross(void) __attribute__ ((const));
      |             ^~~~~~~~~
/home/paul/FTL/src/args.c:426:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  426 | {
      | ^
/home/paul/FTL/src/args.h:21:13: Note: previous declaration here
   21 | const char *cli_info(void) __attribute__ ((const));
      |             ^~~~~~~~
/home/paul/FTL/src/args.c:426:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  426 | {
      | ^
/home/paul/FTL/src/args.h:21:13: Note: previous declaration here
   21 | const char *cli_info(void) __attribute__ ((const));
      |             ^~~~~~~~
/home/paul/FTL/src/args.c:438:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  438 | {
      | ^
/home/paul/FTL/src/args.h:23:13: Note: previous declaration here
   23 | const char *cli_done(void) __attribute__ ((const));
      |             ^~~~~~~~
/home/paul/FTL/src/args.c:438:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  438 | {
      | ^
/home/paul/FTL/src/args.h:23:13: Note: previous declaration here
   23 | const char *cli_done(void) __attribute__ ((const));
      |             ^~~~~~~~
/home/paul/FTL/src/args.c:444:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  444 | {
      | ^
/home/paul/FTL/src/args.h:24:13: Note: previous declaration here
   24 | const char *cli_bold(void) __attribute__ ((const));
      |             ^~~~~~~~
/home/paul/FTL/src/args.c:444:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  444 | {
      | ^
/home/paul/FTL/src/args.h:24:13: Note: previous declaration here
   24 | const char *cli_bold(void) __attribute__ ((const));
      |             ^~~~~~~~
/home/paul/FTL/src/args.c:450:1:Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  450 | {
      | ^
/home/paul/FTL/src/args.h:25:13: Note: previous declaration here
   25 | const char *cli_normal(void) __attribute__ ((const));
      |             ^~~~~~~~~~
/home/paul/FTL/src/args.c:450:1: Error: attribute "pure" conflicts with attribute "const"; ignored [-Werror=attributes]
  450 | {
      | ^
/home/paul/FTL/src/args.h:25:13: Note: previous declaration here
   25 | const char *cli_normal(void) __attribute__ ((const));
      |             ^~~~~~~~~~
[ 46%] Building C object src/lua/CMakeFiles/lua.dir/lfunc.c.o
/home/paul/FTL/src/args.c: In Funktion »cli_tick«:
/home/paul/FTL/src/args.c:413:43: Error: function could be a candidate for attribute "pure [-Werror=suggest-attribute=pure]
  413 | const char __attribute__ ((const, pure)) *cli_tick(void)
      |                                           ^~~~~~~~
/home/paul/FTL/src/args.c: In Funktion »cli_cross«:
/home/paul/FTL/src/args.c:419:43: Error: function could be a candidate for attribute "pure [-Werror=suggest-attribute=pure]
  419 | const char __attribute__ ((const, pure)) *cli_cross(void)
      |                                           ^~~~~~~~~
/home/paul/FTL/src/args.c: In Funktion »cli_info«:
/home/paul/FTL/src/args.c:425:43: Error: function could be a candidate for attribute "pure [-Werror=suggest-attribute=pure]
  425 | const char __attribute__ ((const, pure)) *cli_info(void)
      |                                           ^~~~~~~~
/home/paul/FTL/src/args.c: In Funktion »cli_done«:
/home/paul/FTL/src/args.c:437:43: Error: function could be a candidate for attribute "pure [-Werror=suggest-attribute=pure]
  437 | const char __attribute__ ((const, pure)) *cli_done(void)
      |                                           ^~~~~~~~
/home/paul/FTL/src/args.c: In Funktion »cli_bold«:
/home/paul/FTL/src/args.c:443:43: Error: function could be a candidate for attribute "pure [-Werror=suggest-attribute=pure]
  443 | const char __attribute__ ((const, pure)) *cli_bold(void)
      |                                           ^~~~~~~~
/home/paul/FTL/src/args.c: In Funktion »cli_normal«:
/home/paul/FTL/src/args.c:449:43: Error: function could be a candidate for attribute "pure [-Werror=suggest-attribute=pure]
  449 | const char __attribute__ ((const, pure)) *cli_normal(void)
      |                                           ^~~~~~~~~~
cc1: Alle Warnungen werden als Fehler behandelt
make[2]: *** [src/CMakeFiles/FTL.dir/build.make:76: src/CMakeFiles/FTL.dir/args.c.o] Fehler 1
make[1]: *** [CMakeFiles/Makefile2:237: src/CMakeFiles/FTL.dir/all] Fehler 2
make[1]: *** Es wird auf noch nicht beendete Prozesse gewartet....
[ 46%] Building C object src/lua/CMakeFiles/lua.dir/lgc.c.o

DL6ER · 2022-09-16T17:59:08Z

It somewhat looks rather odd what you are seeing there. How about doing what it suggests?

function could be a candidate for attribute "pure

so something like

-const char __attribute__ ((const)) *cli_tick(void)
+const char __attribute__ ((pure)) *cli_tick(void)

?

Having said that, I should also say that this would make it worse from a performance optimization point as const is more strict that pure, since functions attributed like this are not allowed to read global memory and purely return the same value all the time (hence, the name const).

paulober · 2022-09-16T22:22:21Z

How about doing what it suggests?

Does still not work... And does also throw errors like:

/home/paul/FTL/src/args.h:24:13: Note: previous declaration here
   24 | const char *cli_bold(void) __attribute__ ((const));
      | ^~~~~~~~
/home/paul/FTL/src/args.c:450:1: Error: attribute "pure" conflicts with attribute "const";

DL6ER · 2022-09-18T09:56:24Z

Sure, you also need to change the attribute there (declaration), not only where you did it now (definition). I'd do it myself (probably using an ArchLinux docker container, but I don't have much time right now and also no knowledge about the commands needed on ArchLinux to set up a system suitable for compilation. I you'd provide what is needed (like which packages need to get installed (and how)), I can try taking a look myself. Otherwise, I'm also happy to assist you further if you want to do this yourself.

paulober · 2022-09-18T10:02:29Z

Sure, you also need to change the attribute there (declaration), not only where you did it now (definition). [...] I'm also happy to assist you further if you want to do this yourself.

I just launched my virtual box and push commit as soon as possible. Thanks for the advice

paulober · 2022-09-18T10:09:52Z

Ok now that i also changed the declaration i suggests const instead of pure:

/home/paul/FTL/src/args.c:443:36: Error: function could be a candidate for attribute »const« [-Werror=suggest-attribute=const]
  443 | const char __attribute__ ((pure)) *cli_bold(void)

Maybe it would be bettwer if we just remove the Werror for const and pure suggestions in the compiler?

DL6ER · 2022-09-18T10:30:35Z

So this looks very much like an unfixable gcc bug in ArchLinux (suggesting pure when we have const, suggesting const when we have pure). As far as I remember, Arch's whole philosophy is tailored around "bleeding edge" and this may be one of the problems that are kind of foreseeable with such an approach. Hopefully, this will be resolved soon - have you checked if there is already a bug report for this? If not, it is surely worthwhile to open one.

Even when we'd relax FTLs philosophy to enforce zero compile warnings for the code, we'd still have an unresolvable warning which just feels wrong in every direction I can think of.

paulober · 2022-09-18T17:41:01Z

@DL6ER Yes that's true, the version i used is GCC 12.2.0 which has been released on 19th August 2022 so very bleeding edge.
And i found a bug report which seems to be the one we have: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105676

It says "retargeting bugs to GCC 12.3."...

DL6ER · 2022-09-24T06:20:51Z

I've just seen your edit, this doesn't look good. So I guess this becomes a "won't fix" until GCC 12.3 then?

DL6ER · 2022-11-06T12:48:18Z

@paulober This has been addressed in #1465 - would be nice if you could confirm the current development branch builds fine on your system. I'm going to close this PR now.

paulober · 2022-11-06T19:02:49Z

@paulober This has been addressed in #1465 - would be nice if you could confirm the current development branch builds fine on your system. I'm going to close this PR now.

I replied in the linked pr. But why haven't you just commited to this pr?

DL6ER · 2022-11-06T19:21:08Z

Because I had to fix this myself in a different context and just cheery-picked my commit from over there. It wasn't compatible with your branch due to quite a few conflicts and resolving them didn't look like a fun thing to do when I already had a commit that applied cleanly on the development branch

DL6ER changed the base branch from master to development September 8, 2022 10:40

DL6ER added the Waiting for feedback label Sep 8, 2022

paulober force-pushed the fix-1424-api-warning-listInterfaces branch from 4023864 to 02fe348 Compare September 8, 2022 21:16

Fix pi-hole#1424, api warning listInterfaces

bbe752e

gcc 12.1.1 optimization Signed-off-by: paulober <44974737+paulober@users.noreply.github.com>

paulober force-pushed the fix-1424-api-warning-listInterfaces branch from 02fe348 to bbe752e Compare September 9, 2022 08:57

DL6ER added Discussion and removed Waiting for feedback labels Sep 18, 2022

DL6ER added the External issue label Sep 24, 2022

DL6ER closed this Nov 6, 2022

paulober deleted the fix-1424-api-warning-listInterfaces branch November 6, 2022 23:17

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Fix #1424, api warning listInterfaces #1428

Fix #1424, api warning listInterfaces #1428

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Fix #1424, api warning listInterfaces #1428

Fix #1424, api warning listInterfaces #1428

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