lttng-ust with --std=c99 -pedantic

I want to add lttng-ust tracepoints to a program which builds with "--std=c99 -pedantic". Right now this does not work.

Using the demo program as an example, if you enable --std=c99, the first issue looks like:

jscott@saaz:~/src/lttng-ust/tests/demo$ ccache gcc -std=c99 -DHAVE_CONFIG_H -I. -I../.. -I../../include/lttng  -I../../include -Wall -g -O2 -MT demo.o -MD -MP -MF .deps/demo.Tpo -c -o demo.o demo.c
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___starting’:
ust_tests_demo.h:27:23: warning: implicit declaration of function ‘typeof’ [-Wimplicit-function-declaration]
ust_tests_demo.h:27:218: error: expected ‘;’ before ‘_________p1’
ust_tests_demo.h:27:395: error: ‘_________p1’ undeclared (first use in this function)
ust_tests_demo.h:27:395: note: each undeclared identifier is reported only once for each function it appears in
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___done’:
ust_tests_demo.h:35:214: error: expected ‘;’ before ‘_________p1’
ust_tests_demo.h:35:383: error: ‘_________p1’ undeclared (first use in this function)
In file included from demo.c:35:0:
ust_tests_demo2.h: In function ‘__tracepoint_cb_ust_tests_demo2___loop’:
ust_tests_demo2.h:27:299: error: expected ‘;’ before ‘_________p1’
ust_tests_demo2.h:27:470: error: ‘_________p1’ undeclared (first use in this function)
In file included from demo.c:36:0:
ust_tests_demo3.h: In function ‘__tracepoint_cb_ust_tests_demo3___done’:
ust_tests_demo3.h:27:215: error: expected ‘;’ before ‘_________p1’
ust_tests_demo3.h:27:386: error: ‘_________p1’ undeclared (first use in this function)

This can be easily resolved by using __typeof__() instead of typeof(). Then I can build with --std=c99. But adding -pedantic still fails:

jscott@saaz:~/src/lttng-ust/tests/demo$ ccache gcc -std=c99 -Dtypeof=__typeof__ -pedantic -DHAVE_CONFIG_H -I. -I../.. -I../../include/lttng  -I../../include -Wall -g -O2 -MT demo.o -MD -MP -MF .deps/demo.Tpo -c -o demo.o demo.c
In file included from ust_tests_demo.h:25:0,
                 from demo.c:34:
../../include/lttng/tracepoint.h: In function ‘__tracepoints__init’:
../../include/lttng/tracepoint.h:251:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:255:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:260:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:264:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:268:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___starting’:
ust_tests_demo.h:27:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo.h:27:549: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___done’:
ust_tests_demo.h:35:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo.h:35:537: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

In file included from demo.c:35:0:
ust_tests_demo2.h: In function ‘__tracepoint_cb_ust_tests_demo2___loop’:
ust_tests_demo2.h:27:245: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo2.h:27:624: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:36:0:
ust_tests_demo3.h: In function ‘__tracepoint_cb_ust_tests_demo3___done’:
ust_tests_demo3.h:27:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo3.h:27:540: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

This is with 4.6.1-9ubuntu3 on Ubuntu 11.10, lttng-ust master 5a821c.

Would it be particularly difficult to make the lttng-ust tracepoints compatible with programs built with -pedantic?

cheers,

John

_______________________________________________
lttng-dev mailing list
[email protected]
http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

Hi John,

Quoted 24 lines · * John Steele Scott ([email protected]) wrote:

I want to add lttng-ust tracepoints to a program which builds with "--std=c99 -pedantic". Right now this does not work.

Using the demo program as an example, if you enable --std=c99, the first issue looks like:

jscott@saaz:~/src/lttng-ust/tests/demo$ ccache gcc -std=c99 -DHAVE_CONFIG_H -I. -I../.. -I../../include/lttng  -I../../include -Wall -g -O2 -MT demo.o -MD -MP -MF .deps/demo.Tpo -c -o demo.o demo.c
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___starting’:
ust_tests_demo.h:27:23: warning: implicit declaration of function ‘typeof’ [-Wimplicit-function-declaration]
ust_tests_demo.h:27:218: error: expected ‘;’ before ‘_________p1’
ust_tests_demo.h:27:395: error: ‘_________p1’ undeclared (first use in this function)
ust_tests_demo.h:27:395: note: each undeclared identifier is reported only once for each function it appears in
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___done’:
ust_tests_demo.h:35:214: error: expected ‘;’ before ‘_________p1’
ust_tests_demo.h:35:383: error: ‘_________p1’ undeclared (first use in this function)
In file included from demo.c:35:0:
ust_tests_demo2.h: In function ‘__tracepoint_cb_ust_tests_demo2___loop’:
ust_tests_demo2.h:27:299: error: expected ‘;’ before ‘_________p1’
ust_tests_demo2.h:27:470: error: ‘_________p1’ undeclared (first use in this function)
In file included from demo.c:36:0:
ust_tests_demo3.h: In function ‘__tracepoint_cb_ust_tests_demo3___done’:
ust_tests_demo3.h:27:215: error: expected ‘;’ before ‘_________p1’
ust_tests_demo3.h:27:386: error: ‘_________p1’ undeclared (first use in this function)

Quoted 1 line

This can be easily resolved by using __typeof__() instead of typeof(). Then I can build with --std=c99. But adding -pedantic still fails:

I pushed a fix for this:

commit 6423c3134bf07d4a7db56f69f2c79b540a79c4f1

Author: Mathieu Desnoyers <[email protected]>
Date:   Mon Jun 11 10:15:25 2012 -0400

Fix c99 compatibility: use __typeof__ instead of typeof in public headers

Reported-by John Steele Scott <[email protected]>

Signed-off-by Mathieu Desnoyers <[email protected]>

I also had issues with (void) arg parameters with tracepoints, so pushed:

commit 4495dd39c05739d0fb2bc463b7c093d2459ce2b6

Author: Mathieu Desnoyers <[email protected]>
Date:   Tue Jun 12 11:22:46 2012 -0400

Fix: support -std=c99 in tracepoint macros

Signed-off-by Mathieu Desnoyers <[email protected]>

I had also to fix userspace RCU library, with:

commit e51500edbd9919cee53bc85cbb4b22cd4786fc42

Author: Mathieu Desnoyers <[email protected]>
Date:   Tue Jun 12 11:24:31 2012 -0400

Fix c99 compatibility: use __asm__ and __volatile__ in public headers

Signed-off-by Mathieu Desnoyers <[email protected]>

commit bdffa73aa208ad5f1e5b3a3cb6cbf86ac6996559

Author: Mathieu Desnoyers <[email protected]>
Date:   Mon Jun 11 10:16:35 2012 -0400

Fix c99 compatibility: use __typeof__ instead of typeof in public headers

Reported-by John Steele Scott <[email protected]>

Signed-off-by Mathieu Desnoyers <[email protected]>

Quoted 18 lines

jscott@saaz:~/src/lttng-ust/tests/demo$ ccache gcc -std=c99 -Dtypeof=__typeof__ -pedantic -DHAVE_CONFIG_H -I. -I../.. -I../../include/lttng  -I../../include -Wall -g -O2 -MT demo.o -MD -MP -MF .deps/demo.Tpo -c -o demo.o demo.c
In file included from ust_tests_demo.h:25:0,
                 from demo.c:34:
../../include/lttng/tracepoint.h: In function ‘__tracepoints__init’:
../../include/lttng/tracepoint.h:251:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:255:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:260:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:264:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:268:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___starting’:
ust_tests_demo.h:27:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo.h:27:549: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___done’:
ust_tests_demo.h:35:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo.h:35:537: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

Quoted 8 lines

In file included from demo.c:35:0:
ust_tests_demo2.h: In function ‘__tracepoint_cb_ust_tests_demo2___loop’:
ust_tests_demo2.h:27:245: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo2.h:27:624: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:36:0:
ust_tests_demo3.h: In function ‘__tracepoint_cb_ust_tests_demo3___done’:
ust_tests_demo3.h:27:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo3.h:27:540: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

I see these warnings, the only thing that currently fails is due to BYTE_ORDER and BIG_ENDIAN not being defined. By adding:

-DBYTE_ORDER=__BYTE_ORDER -DBIG_ENDIAN=__BIG_ENDIAN

my tests/hello program, with a Makefile.am modified to do:

hello_CFLAGS = -Werror=old-style-definition --std=c99 -pedantic

prints many pedantic warnings, and fails with:

././ust_tests_hello.h:55:1: error: zero or negative size array ‘__event_fields___ust_tests_hello___tptest_sighandler’

which seems to be caused by my event with 0 fields, which try to create an array of length 0.

I'll look into this one.

Thanks,

Mathieu

Quoted 14 lines

This is with 4.6.1-9ubuntu3 on Ubuntu 11.10, lttng-ust master 5a821c.

Would it be particularly difficult to make the lttng-ust tracepoints compatible with programs built with -pedantic?

cheers,

John

_______________________________________________
lttng-dev mailing list
[email protected]
http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

Signature · 9 lines

Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

_______________________________________________
lttng-dev mailing list
[email protected]
http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

Quoted 112 lines · * Mathieu Desnoyers ([email protected]) wrote:

Hi John,

Quoted 24 lines · * John Steele Scott ([email protected]) wrote:

I want to add lttng-ust tracepoints to a program which builds with "--std=c99 -pedantic". Right now this does not work.

Using the demo program as an example, if you enable --std=c99, the first issue looks like:

jscott@saaz:~/src/lttng-ust/tests/demo$ ccache gcc -std=c99 -DHAVE_CONFIG_H -I. -I../.. -I../../include/lttng  -I../../include -Wall -g -O2 -MT demo.o -MD -MP -MF .deps/demo.Tpo -c -o demo.o demo.c
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___starting’:
ust_tests_demo.h:27:23: warning: implicit declaration of function ‘typeof’ [-Wimplicit-function-declaration]
ust_tests_demo.h:27:218: error: expected ‘;’ before ‘_________p1’
ust_tests_demo.h:27:395: error: ‘_________p1’ undeclared (first use in this function)
ust_tests_demo.h:27:395: note: each undeclared identifier is reported only once for each function it appears in
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___done’:
ust_tests_demo.h:35:214: error: expected ‘;’ before ‘_________p1’
ust_tests_demo.h:35:383: error: ‘_________p1’ undeclared (first use in this function)
In file included from demo.c:35:0:
ust_tests_demo2.h: In function ‘__tracepoint_cb_ust_tests_demo2___loop’:
ust_tests_demo2.h:27:299: error: expected ‘;’ before ‘_________p1’
ust_tests_demo2.h:27:470: error: ‘_________p1’ undeclared (first use in this function)
In file included from demo.c:36:0:
ust_tests_demo3.h: In function ‘__tracepoint_cb_ust_tests_demo3___done’:
ust_tests_demo3.h:27:215: error: expected ‘;’ before ‘_________p1’
ust_tests_demo3.h:27:386: error: ‘_________p1’ undeclared (first use in this function)

Quoted 1 line

This can be easily resolved by using __typeof__() instead of typeof(). Then I can build with --std=c99. But adding -pedantic still fails:

I pushed a fix for this:

commit 6423c3134bf07d4a7db56f69f2c79b540a79c4f1

Author: Mathieu Desnoyers <[email protected]>
Date:   Mon Jun 11 10:15:25 2012 -0400

Fix c99 compatibility: use __typeof__ instead of typeof in public headers

Reported-by John Steele Scott <[email protected]>

Signed-off-by Mathieu Desnoyers <[email protected]>

I also had issues with (void) arg parameters with tracepoints, so pushed:

commit 4495dd39c05739d0fb2bc463b7c093d2459ce2b6

Author: Mathieu Desnoyers <[email protected]>
Date:   Tue Jun 12 11:22:46 2012 -0400

Fix: support -std=c99 in tracepoint macros

Signed-off-by Mathieu Desnoyers <[email protected]>

I had also to fix userspace RCU library, with:

commit e51500edbd9919cee53bc85cbb4b22cd4786fc42

Author: Mathieu Desnoyers <[email protected]>
Date:   Tue Jun 12 11:24:31 2012 -0400

Fix c99 compatibility: use __asm__ and __volatile__ in public headers

Signed-off-by Mathieu Desnoyers <[email protected]>

commit bdffa73aa208ad5f1e5b3a3cb6cbf86ac6996559

Author: Mathieu Desnoyers <[email protected]>
Date:   Mon Jun 11 10:16:35 2012 -0400

Fix c99 compatibility: use __typeof__ instead of typeof in public headers

Reported-by John Steele Scott <[email protected]>

Signed-off-by Mathieu Desnoyers <[email protected]>

Quoted 17 lines

jscott@saaz:~/src/lttng-ust/tests/demo$ ccache gcc -std=c99 -Dtypeof=__typeof__ -pedantic -DHAVE_CONFIG_H -I. -I../.. -I../../include/lttng  -I../../include -Wall -g -O2 -MT demo.o -MD -MP -MF .deps/demo.Tpo -c -o demo.o demo.c
In file included from ust_tests_demo.h:25:0,
                 from demo.c:34:
../../include/lttng/tracepoint.h: In function ‘__tracepoints__init’:
../../include/lttng/tracepoint.h:251:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:255:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:260:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:264:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:268:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___starting’:
ust_tests_demo.h:27:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo.h:27:549: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___done’:
ust_tests_demo.h:35:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo.h:35:537: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

Quoted 8 lines

In file included from demo.c:35:0:
ust_tests_demo2.h: In function ‘__tracepoint_cb_ust_tests_demo2___loop’:
ust_tests_demo2.h:27:245: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo2.h:27:624: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:36:0:
ust_tests_demo3.h: In function ‘__tracepoint_cb_ust_tests_demo3___done’:
ust_tests_demo3.h:27:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo3.h:27:540: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

I see these warnings, the only thing that currently fails is due to BYTE_ORDER and BIG_ENDIAN not being defined. By adding:

-DBYTE_ORDER=__BYTE_ORDER -DBIG_ENDIAN=__BIG_ENDIAN

my tests/hello program, with a Makefile.am modified to do:

hello_CFLAGS = -Werror=old-style-definition --std=c99 -pedantic

prints many pedantic warnings, and fails with:

././ust_tests_hello.h:55:1: error: zero or negative size array ‘__event_fields___ust_tests_hello___tptest_sighandler’

which seems to be caused by my event with 0 fields, which try to create an array of length 0.

Quoted 1 line

I'll look into this one.

Please try again with lttng-ust master HEAD, userspace-rcu master HEAD, and let me know if you experience problems compiling your instrumented application with --std=c99 -pedantic. Please note that the probe object (e.g. tp.c in the tests/hello program) needs to be compiled with gnu extensions, so you should not use --std=c99 for this specific object.

Quoted 113 lines · Mathieu Desnoyers

Quoted 112 lines · * Mathieu Desnoyers ([email protected]) wrote:

Hi John,

Quoted 24 lines · * John Steele Scott ([email protected]) wrote:

I want to add lttng-ust tracepoints to a program which builds with "--std=c99 -pedantic". Right now this does not work.

Using the demo program as an example, if you enable --std=c99, the first issue looks like:

jscott@saaz:~/src/lttng-ust/tests/demo$ ccache gcc -std=c99 -DHAVE_CONFIG_H -I. -I../.. -I../../include/lttng  -I../../include -Wall -g -O2 -MT demo.o -MD -MP -MF .deps/demo.Tpo -c -o demo.o demo.c
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___starting’:
ust_tests_demo.h:27:23: warning: implicit declaration of function ‘typeof’ [-Wimplicit-function-declaration]
ust_tests_demo.h:27:218: error: expected ‘;’ before ‘_________p1’
ust_tests_demo.h:27:395: error: ‘_________p1’ undeclared (first use in this function)
ust_tests_demo.h:27:395: note: each undeclared identifier is reported only once for each function it appears in
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___done’:
ust_tests_demo.h:35:214: error: expected ‘;’ before ‘_________p1’
ust_tests_demo.h:35:383: error: ‘_________p1’ undeclared (first use in this function)
In file included from demo.c:35:0:
ust_tests_demo2.h: In function ‘__tracepoint_cb_ust_tests_demo2___loop’:
ust_tests_demo2.h:27:299: error: expected ‘;’ before ‘_________p1’
ust_tests_demo2.h:27:470: error: ‘_________p1’ undeclared (first use in this function)
In file included from demo.c:36:0:
ust_tests_demo3.h: In function ‘__tracepoint_cb_ust_tests_demo3___done’:
ust_tests_demo3.h:27:215: error: expected ‘;’ before ‘_________p1’
ust_tests_demo3.h:27:386: error: ‘_________p1’ undeclared (first use in this function)

Quoted 1 line

This can be easily resolved by using __typeof__() instead of typeof(). Then I can build with --std=c99. But adding -pedantic still fails:

I pushed a fix for this:

commit 6423c3134bf07d4a7db56f69f2c79b540a79c4f1

Author: Mathieu Desnoyers <[email protected]>
Date:   Mon Jun 11 10:15:25 2012 -0400

Fix c99 compatibility: use __typeof__ instead of typeof in public headers

Reported-by John Steele Scott <[email protected]>

Signed-off-by Mathieu Desnoyers <[email protected]>

I also had issues with (void) arg parameters with tracepoints, so pushed:

commit 4495dd39c05739d0fb2bc463b7c093d2459ce2b6

Author: Mathieu Desnoyers <[email protected]>
Date:   Tue Jun 12 11:22:46 2012 -0400

Fix: support -std=c99 in tracepoint macros

Signed-off-by Mathieu Desnoyers <[email protected]>

I had also to fix userspace RCU library, with:

commit e51500edbd9919cee53bc85cbb4b22cd4786fc42

Author: Mathieu Desnoyers <[email protected]>
Date:   Tue Jun 12 11:24:31 2012 -0400

Fix c99 compatibility: use __asm__ and __volatile__ in public headers

Signed-off-by Mathieu Desnoyers <[email protected]>

commit bdffa73aa208ad5f1e5b3a3cb6cbf86ac6996559

Author: Mathieu Desnoyers <[email protected]>
Date:   Mon Jun 11 10:16:35 2012 -0400

Fix c99 compatibility: use __typeof__ instead of typeof in public headers

Reported-by John Steele Scott <[email protected]>

Signed-off-by Mathieu Desnoyers <[email protected]>

Quoted 17 lines

jscott@saaz:~/src/lttng-ust/tests/demo$ ccache gcc -std=c99 -Dtypeof=__typeof__ -pedantic -DHAVE_CONFIG_H -I. -I../.. -I../../include/lttng  -I../../include -Wall -g -O2 -MT demo.o -MD -MP -MF .deps/demo.Tpo -c -o demo.o demo.c
In file included from ust_tests_demo.h:25:0,
                 from demo.c:34:
../../include/lttng/tracepoint.h: In function ‘__tracepoints__init’:
../../include/lttng/tracepoint.h:251:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:255:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:260:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:264:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:268:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___starting’:
ust_tests_demo.h:27:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo.h:27:549: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___done’:
ust_tests_demo.h:35:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo.h:35:537: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

Quoted 8 lines

In file included from demo.c:35:0:
ust_tests_demo2.h: In function ‘__tracepoint_cb_ust_tests_demo2___loop’:
ust_tests_demo2.h:27:245: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo2.h:27:624: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:36:0:
ust_tests_demo3.h: In function ‘__tracepoint_cb_ust_tests_demo3___done’:
ust_tests_demo3.h:27:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo3.h:27:540: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

I see these warnings, the only thing that currently fails is due to BYTE_ORDER and BIG_ENDIAN not being defined. By adding:

-DBYTE_ORDER=__BYTE_ORDER -DBIG_ENDIAN=__BIG_ENDIAN

my tests/hello program, with a Makefile.am modified to do:

hello_CFLAGS = -Werror=old-style-definition --std=c99 -pedantic

prints many pedantic warnings, and fails with:

././ust_tests_hello.h:55:1: error: zero or negative size array ‘__event_fields___ust_tests_hello___tptest_sighandler’

which seems to be caused by my event with 0 fields, which try to create an array of length 0.

Quoted 6 lines

Quoted 1 line

I'll look into this one.

Please try again with lttng-ust master HEAD, userspace-rcu master HEAD, and let me know if you experience problems compiling your instrumented application with --std=c99 -pedantic. Please note that the probe object (e.g. tp.c in the tests/hello program) needs to be compiled with gnu extensions, so you should not use --std=c99 for this specific object.

Mathieu,

Thanks for your reply, sorry it has taken me so long to respond.

I can now build this application with userspace tracing. I was actually able to compile the probe object with --std=c99 as well (this time on Centos 6.2, didn't try yet on Ubuntu). Would you expect any problems from this? I only have a single tracepoint in this app, but it does seem to work.

The thing I forgot to mention is: okay, I can build now with -pedantic, but I can't build with "-pedantic -Werror". This application builds with "--std=c99 -pedantic -Werror" (among many other flags). I can of course remove -Werror for my tests, but in the longer term I would like to see lttng-ust enabled in our regular build, and disabling -Werror for that is not something we want to do. If I only had to disable it for the trace provider, I could negotiate that, but disabling it for any module which uses tracepoints is undesirable.

I haven't yet looked at how difficult it would be do eliminate these pedantic warnings. Do you have a feel for what is involved? Preprocessor tricks warp my mind. :(

cheers,

John

_______________________________________________
lttng-dev mailing list
[email protected]
http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

Quoted 123 lines · * John Steele Scott ([email protected]) wrote:

Quoted 113 lines · Mathieu Desnoyers

Quoted 112 lines · * Mathieu Desnoyers ([email protected]) wrote:

Hi John,

Quoted 24 lines · * John Steele Scott ([email protected]) wrote:

I want to add lttng-ust tracepoints to a program which builds with "--std=c99 -pedantic". Right now this does not work.

Using the demo program as an example, if you enable --std=c99, the first issue looks like:

jscott@saaz:~/src/lttng-ust/tests/demo$ ccache gcc -std=c99 -DHAVE_CONFIG_H -I. -I../.. -I../../include/lttng  -I../../include -Wall -g -O2 -MT demo.o -MD -MP -MF .deps/demo.Tpo -c -o demo.o demo.c
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___starting’:
ust_tests_demo.h:27:23: warning: implicit declaration of function ‘typeof’ [-Wimplicit-function-declaration]
ust_tests_demo.h:27:218: error: expected ‘;’ before ‘_________p1’
ust_tests_demo.h:27:395: error: ‘_________p1’ undeclared (first use in this function)
ust_tests_demo.h:27:395: note: each undeclared identifier is reported only once for each function it appears in
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___done’:
ust_tests_demo.h:35:214: error: expected ‘;’ before ‘_________p1’
ust_tests_demo.h:35:383: error: ‘_________p1’ undeclared (first use in this function)
In file included from demo.c:35:0:
ust_tests_demo2.h: In function ‘__tracepoint_cb_ust_tests_demo2___loop’:
ust_tests_demo2.h:27:299: error: expected ‘;’ before ‘_________p1’
ust_tests_demo2.h:27:470: error: ‘_________p1’ undeclared (first use in this function)
In file included from demo.c:36:0:
ust_tests_demo3.h: In function ‘__tracepoint_cb_ust_tests_demo3___done’:
ust_tests_demo3.h:27:215: error: expected ‘;’ before ‘_________p1’
ust_tests_demo3.h:27:386: error: ‘_________p1’ undeclared (first use in this function)

Quoted 1 line

This can be easily resolved by using __typeof__() instead of typeof(). Then I can build with --std=c99. But adding -pedantic still fails:

I pushed a fix for this:

commit 6423c3134bf07d4a7db56f69f2c79b540a79c4f1

Author: Mathieu Desnoyers <[email protected]>
Date:   Mon Jun 11 10:15:25 2012 -0400

Fix c99 compatibility: use __typeof__ instead of typeof in public headers

Reported-by John Steele Scott <[email protected]>

Signed-off-by Mathieu Desnoyers <[email protected]>

I also had issues with (void) arg parameters with tracepoints, so pushed:

commit 4495dd39c05739d0fb2bc463b7c093d2459ce2b6

Author: Mathieu Desnoyers <[email protected]>
Date:   Tue Jun 12 11:22:46 2012 -0400

Fix: support -std=c99 in tracepoint macros

Signed-off-by Mathieu Desnoyers <[email protected]>

I had also to fix userspace RCU library, with:

commit e51500edbd9919cee53bc85cbb4b22cd4786fc42

Author: Mathieu Desnoyers <[email protected]>
Date:   Tue Jun 12 11:24:31 2012 -0400

Fix c99 compatibility: use __asm__ and __volatile__ in public headers

Signed-off-by Mathieu Desnoyers <[email protected]>

commit bdffa73aa208ad5f1e5b3a3cb6cbf86ac6996559

Author: Mathieu Desnoyers <[email protected]>
Date:   Mon Jun 11 10:16:35 2012 -0400

Fix c99 compatibility: use __typeof__ instead of typeof in public headers

Reported-by John Steele Scott <[email protected]>

Signed-off-by Mathieu Desnoyers <[email protected]>

Quoted 17 lines

jscott@saaz:~/src/lttng-ust/tests/demo$ ccache gcc -std=c99 -Dtypeof=__typeof__ -pedantic -DHAVE_CONFIG_H -I. -I../.. -I../../include/lttng  -I../../include -Wall -g -O2 -MT demo.o -MD -MP -MF .deps/demo.Tpo -c -o demo.o demo.c
In file included from ust_tests_demo.h:25:0,
                 from demo.c:34:
../../include/lttng/tracepoint.h: In function ‘__tracepoints__init’:
../../include/lttng/tracepoint.h:251:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:255:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:260:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:264:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
../../include/lttng/tracepoint.h:268:4: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___starting’:
ust_tests_demo.h:27:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo.h:27:549: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:34:0:
ust_tests_demo.h: In function ‘__tracepoint_cb_ust_tests_demo___done’:
ust_tests_demo.h:35:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo.h:35:537: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

Quoted 8 lines

In file included from demo.c:35:0:
ust_tests_demo2.h: In function ‘__tracepoint_cb_ust_tests_demo2___loop’:
ust_tests_demo2.h:27:245: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo2.h:27:624: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]
In file included from demo.c:36:0:
ust_tests_demo3.h: In function ‘__tracepoint_cb_ust_tests_demo3___done’:
ust_tests_demo3.h:27:161: warning: ISO C forbids braced-groups within expressions [-pedantic]
ust_tests_demo3.h:27:540: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

I see these warnings, the only thing that currently fails is due to BYTE_ORDER and BIG_ENDIAN not being defined. By adding:

-DBYTE_ORDER=__BYTE_ORDER -DBIG_ENDIAN=__BIG_ENDIAN

my tests/hello program, with a Makefile.am modified to do:

hello_CFLAGS = -Werror=old-style-definition --std=c99 -pedantic

prints many pedantic warnings, and fails with:

././ust_tests_hello.h:55:1: error: zero or negative size array ‘__event_fields___ust_tests_hello___tptest_sighandler’

which seems to be caused by my event with 0 fields, which try to create an array of length 0.

Quoted 6 lines

Quoted 1 line

I'll look into this one.

Please try again with lttng-ust master HEAD, userspace-rcu master HEAD, and let me know if you experience problems compiling your instrumented application with --std=c99 -pedantic. Please note that the probe object (e.g. tp.c in the tests/hello program) needs to be compiled with gnu extensions, so you should not use --std=c99 for this specific object.

Mathieu,

Quoted 7 lines

Thanks for your reply, sorry it has taken me so long to respond.

I can now build this application with userspace tracing. I was actually able to compile the probe object with --std=c99 as well (this time on Centos 6.2, didn't try yet on Ubuntu). Would you expect any problems from this? I only have a single tracepoint in this app, but it does seem to work.

--std=c99 will not work to compile probes containing tracepoints taking 0 arguments. This is because c99 does not allow 0-sized arrays, and I don't want to complexify the probe generation to take care of this issue.

Quoted 11 lines

The thing I forgot to mention is: okay, I can build now with -pedantic, but I can't build with "-pedantic -Werror". This application builds with "--std=c99 -pedantic -Werror" (among many other flags). I can of course remove -Werror for my tests, but in the longer term I would like to see lttng-ust enabled in our regular build, and disabling -Werror for that is not something we want to do. If I only had to disable it for the trace provider, I could negotiate that, but disabling it for any module which uses tracepoints is undesirable.

Quoted 3 lines

I haven't yet looked at how difficult it would be do eliminate these pedantic warnings. Do you have a feel for what is involved? Preprocessor tricks warp my mind. :(

I don't think we'll want to make the lttng probe module build under --std=c99 -pedandic -Werror, but I think we should focus on making sure the tracepoint part that is built within the application (with TRACEPOINT_CREATE_PROBES _not_ defined) builds fine in --std=c99 -pedantic.

Currently, building a simple test program with tracepoints under --std=c99 -pedantic gets me:

In file included from ust_tests_hello.h:25:0,

                 from hello.c:34:

../../include/lttng/tracepoint.h: In function ‘__tracepoints__init’:
../../include/lttng/tracepoint.h:261:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:265:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:270:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:274:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:278:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

---> see include/lttng/tracepoint.h __tracepoints__init():
----> This is caused by use of dlsym() to lookup a function pointer from
a symbol. dlsym() returns "void *", and we cast it into function pointer type. Ideas on how to make this c99 pedantic compliant are welcome.

------------------

In file included from hello.c:34:0:
ust_tests_hello.h: In function ‘__tracepoint_cb_ust_tests_hello___tptest’:
ust_tests_hello.h:28:1: warning: ISO C forbids braced-groups within expressions [-pedantic] ust_tests_hello.h:28:1: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ust_tests_hello.h: In function ‘__tracepoint_cb_ust_tests_hello___tptest_sighandler’:
ust_tests_hello.h:52:1: warning: ISO C forbids braced-groups within expressions [-pedantic] ust_tests_hello.h:52:1: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

---> see include/lttng/tracepoint.h

#define _DECLARE_TRACEPOINT(_provider, _name, ...) \
extern struct tracepoint __tracepoint_##_provider##___##_name; \
static inline void __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__)) \
[...]

----> this is caused by use of "tp_rcu_dereference_bp()", which is defined in include/lttng/tracepoint-rcu.h (in the #else clause) :

#define tp_rcu_dereference_bp(p)                                             \
        ({                                                                   \
                __typeof__(p) _________p1 = URCU_FORCE_CAST(__typeof__(p),   \
                        tracepoint_dlopen.rcu_dereference_sym_bp(URCU_FORCE_CAST(void *, p))); \
                (_________p1);                                               \
        })

For this one, we should be able to change it into a single-expression and remove the braced-groups, since we are just really evaluating a single expression here. Fixed by the following commit in lttng-ust master:

commit a4eaf8eabe829be8f7d7432ffaf83291a068b0ed

Author: Mathieu Desnoyers <[email protected]>
Date:   Mon Jun 18 10:10:36 2012 -0400

Fix c99 compatibility: tp_rcu_dereference_bp() should not use braced-groups within expressions

------------------

hello.c: In function ‘inthandler’:
hello.c:39:47: warning: ISO C99 requires rest arguments to be used [enabled by default] ---> see include/lttng/tracepoint.h tracepoint() macro.
----> this is caused by not passing any argument to the tracepoint.
Ideas on how to fix this are welcome, as I don't see any way to do it in C99-pedantic.

Thanks!

Mathieu

Quoted 9 lines

cheers,

John

_______________________________________________
lttng-dev mailing list
[email protected]
http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

Signature · 9 lines

Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

_______________________________________________
lttng-dev mailing list
[email protected]
http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

Quoted 2 lines · * Mathieu Desnoyers ([email protected]) wrote:

* John Steele Scott ([email protected]) wrote:

Quoted 32 lines

Quoted 10 lines

The thing I forgot to mention is: okay, I can build now with -pedantic, but I can't build with "-pedantic -Werror". This application builds with "--std=c99 -pedantic -Werror" (among many other flags). I can of course remove -Werror for my tests, but in the longer term I would like to see lttng-ust enabled in our regular build, and disabling -Werror for that is not something we want to do. If I only had to disable it for the trace provider, I could negotiate that, but disabling it for any module which uses tracepoints is undesirable.

Quoted 3 lines

I haven't yet looked at how difficult it would be do eliminate these pedantic warnings. Do you have a feel for what is involved? Preprocessor tricks warp my mind. :(

I don't think we'll want to make the lttng probe module build under --std=c99 -pedandic -Werror, but I think we should focus on making sure the tracepoint part that is built within the application (with TRACEPOINT_CREATE_PROBES _not_ defined) builds fine in --std=c99 -pedantic.

Currently, building a simple test program with tracepoints under --std=c99 -pedantic gets me:

In file included from ust_tests_hello.h:25:0,

                 from hello.c:34:

../../include/lttng/tracepoint.h: In function ‘__tracepoints__init’:
../../include/lttng/tracepoint.h:261:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:265:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:270:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:274:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:278:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

Quoted 5 lines

---> see include/lttng/tracepoint.h __tracepoints__init():
----> This is caused by use of dlsym() to lookup a function pointer from
a symbol. dlsym() returns "void *", and we cast it into function pointer type. Ideas on how to make this c99 pedantic compliant are welcome.

Quoted 39 lines

------------------

In file included from hello.c:34:0:
ust_tests_hello.h: In function ‘__tracepoint_cb_ust_tests_hello___tptest’:
ust_tests_hello.h:28:1: warning: ISO C forbids braced-groups within expressions [-pedantic] ust_tests_hello.h:28:1: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ust_tests_hello.h: In function ‘__tracepoint_cb_ust_tests_hello___tptest_sighandler’:
ust_tests_hello.h:52:1: warning: ISO C forbids braced-groups within expressions [-pedantic] ust_tests_hello.h:52:1: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

---> see include/lttng/tracepoint.h

#define _DECLARE_TRACEPOINT(_provider, _name, ...) \
extern struct tracepoint __tracepoint_##_provider##___##_name; \
static inline void __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__)) \
[...]

----> this is caused by use of "tp_rcu_dereference_bp()", which is defined in include/lttng/tracepoint-rcu.h (in the #else clause) :

#define tp_rcu_dereference_bp(p)                                             \
        ({                                                                   \
                __typeof__(p) _________p1 = URCU_FORCE_CAST(__typeof__(p),   \
                        tracepoint_dlopen.rcu_dereference_sym_bp(URCU_FORCE_CAST(void *, p))); \
                (_________p1);                                               \
        })

For this one, we should be able to change it into a single-expression and remove the braced-groups, since we are just really evaluating a single expression here. Fixed by the following commit in lttng-ust master:

commit a4eaf8eabe829be8f7d7432ffaf83291a068b0ed

Author: Mathieu Desnoyers <[email protected]>
Date:   Mon Jun 18 10:10:36 2012 -0400

Fix c99 compatibility: tp_rcu_dereference_bp() should not use braced-groups within expressions

Quoted 8 lines

------------------

hello.c: In function ‘inthandler’:
hello.c:39:47: warning: ISO C99 requires rest arguments to be used [enabled by default] ---> see include/lttng/tracepoint.h tracepoint() macro.
----> this is caused by not passing any argument to the tracepoint.
Ideas on how to fix this are welcome, as I don't see any way to do it in C99-pedantic.

I think I found a way to fix the last pedantic warnings. Can you try with this master branch commit ?

commit fbdeb5ecb8ff9b7d73a72de9fc66d07f7797d93f

Author: Mathieu Desnoyers <[email protected]>
Date:   Tue Jun 19 13:45:05 2012 -0400

Fix C99 strict compatibility: don't use void * for function pointers

compiling public headers with --std=x99 -pedantic shows:

warning: ISO C forbids conversion of object pointer to function pointer type

Use "void (*func)(void)" to represent a generic function pointer rather than "void *".

Signed-off-by Mathieu Desnoyers <[email protected]>

Quoted 3 lines · Mathieu Desnoyers

Quoted 2 lines · * Mathieu Desnoyers ([email protected]) wrote:

* John Steele Scott ([email protected]) wrote:

snip snip

Quoted 32 lines

Quoted 32 lines

Quoted 10 lines

The thing I forgot to mention is: okay, I can build now with -pedantic, but I can't build with "-pedantic -Werror". This application builds with "--std=c99 -pedantic -Werror" (among many other flags). I can of course remove -Werror for my tests, but in the longer term I would like to see lttng-ust enabled in our regular build, and disabling -Werror for that is not something we want to do. If I only had to disable it for the trace provider, I could negotiate that, but disabling it for any module which uses tracepoints is undesirable.

Quoted 3 lines

I haven't yet looked at how difficult it would be do eliminate these pedantic warnings. Do you have a feel for what is involved? Preprocessor tricks warp my mind. :(

I don't think we'll want to make the lttng probe module build under --std=c99 -pedandic -Werror, but I think we should focus on making sure the tracepoint part that is built within the application (with TRACEPOINT_CREATE_PROBES _not_ defined) builds fine in --std=c99 -pedantic.

Currently, building a simple test program with tracepoints under --std=c99 -pedantic gets me:

In file included from ust_tests_hello.h:25:0,

                 from hello.c:34:

../../include/lttng/tracepoint.h: In function ‘__tracepoints__init’:
../../include/lttng/tracepoint.h:261:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:265:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:270:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:274:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:278:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

Quoted 5 lines

Quoted 5 lines

---> see include/lttng/tracepoint.h __tracepoints__init():
----> This is caused by use of dlsym() to lookup a function pointer from
a symbol. dlsym() returns "void *", and we cast it into function pointer type. Ideas on how to make this c99 pedantic compliant are welcome.

I found this warning discussed in a GCC bug report. Jakub Jelinek's suggestion at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45289#c6 (load the result of dlsym into a void *, then memcpy to the function pointer), does make these go away (using GCC 4.4.6 on Centos 6.2).

Quoted 43 lines · * John Steele Scott ([email protected]) wrote:

Quoted 3 lines · Mathieu Desnoyers

Quoted 2 lines · * Mathieu Desnoyers ([email protected]) wrote:

* John Steele Scott ([email protected]) wrote:

snip snip

Quoted 37 lines

Quoted 37 lines

Quoted 10 lines

The thing I forgot to mention is: okay, I can build now with -pedantic, but I can't build with "-pedantic -Werror". This application builds with "--std=c99 -pedantic -Werror" (among many other flags). I can of course remove -Werror for my tests, but in the longer term I would like to see lttng-ust enabled in our regular build, and disabling -Werror for that is not something we want to do. If I only had to disable it for the trace provider, I could negotiate that, but disabling it for any module which uses tracepoints is undesirable.

Quoted 3 lines

I haven't yet looked at how difficult it would be do eliminate these pedantic warnings. Do you have a feel for what is involved? Preprocessor tricks warp my mind. :(

I don't think we'll want to make the lttng probe module build under --std=c99 -pedandic -Werror, but I think we should focus on making sure the tracepoint part that is built within the application (with TRACEPOINT_CREATE_PROBES _not_ defined) builds fine in --std=c99 -pedantic.

Currently, building a simple test program with tracepoints under --std=c99 -pedantic gets me:

In file included from ust_tests_hello.h:25:0,

                 from hello.c:34:

../../include/lttng/tracepoint.h: In function ‘__tracepoints__init’:
../../include/lttng/tracepoint.h:261:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:265:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:270:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:274:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic] ../../include/lttng/tracepoint.h:278:3: warning: ISO C forbids conversion of object pointer to function pointer type [-pedantic]

---> see include/lttng/tracepoint.h __tracepoints__init():
----> This is caused by use of dlsym() to lookup a function pointer from
a symbol. dlsym() returns "void *", and we cast it into function pointer type. Ideas on how to make this c99 pedantic compliant are welcome.

Quoted 1 line

I found this warning discussed in a GCC bug report. Jakub Jelinek's suggestion at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45289#c6 (load the result of dlsym into a void *, then memcpy to the function pointer), does make these go away (using GCC 4.4.6 on Centos 6.2).

Can you check if these can be reproduced with gcc 4.5 or 4.6 ? (without the memcpy trick)

The bugzilla entry seems to imply that the warning went away from -pedantic mode at some point.