digitalmars.D - Linking C & extern(C) on OS X: duplicate symbols not flagged
- =?UTF-8?B?Ikx1w61z?= Marques" (31/31) Aug 29 2013 On Linux, the following gives out a "multiple definition" error,
- Jacob Carlborg (4/30) Aug 29 2013 How does it behave on Mac OS X if you just use C?
- =?UTF-8?B?Ikx1w61z?= Marques" (3/9) Aug 30 2013 That fails, as expected.
- Jacob Carlborg (4/5) Aug 31 2013 So DMD and Clang uses different sections? Have you tried GDC or LDC?
- =?UTF-8?B?Ikx1w61z?= Marques" (20/22) Sep 03 2013 Sorry for the delay.
- Jacob Carlborg (6/23) Sep 03 2013 Perhaps time to file a bug report. I don't know if there's a reason to
- =?UTF-8?B?Ikx1w61z?= Marques" (6/8) Sep 04 2013 I posted it here hoping Walter might comment on this. Maybe he
- =?UTF-8?B?Ikx1w61z?= Marques" (6/10) Oct 08 2013 Since Walter did not comment on this, I posted a bug:
On Linux, the following gives out a "multiple definition" error, as expected: c/test.c: void dotest(void) { printf("C\n"); } d/test.d: extern(C) void dotest() { writeln("D"); } On OS X no error is flagged, and the C function is always called, irrespective of which order I specify the .o files to link. Yet, compiling and linking two .c files with a duplication symbol does give an error on the linking phase, as expected. So why the discrepancy? I'm guessing the cause is the section where the symbols appear: On Ubuntu: $ nm d/test.o | grep dotest; echo "--"; nm c/test.o | grep dotest 0000000000000000 T dotest -- 0000000000000000 T dotest On OS X: $ nm d/test.o | grep dotest; echo "--"; nm c/test.o | grep dotest 0000000000001490 S _dotest <-- not in text section, as in Linux -- 0000000000000000 T _dotest 0000000000000060 S _dotest.eh As you might imagine, this situation can be highly disruptive (I'm progressively converting a C application to D). Do you know why the functions appear in the S section on OS X? Do you know of any workaround, to assure that duplicate symbols are correctly flagged?
Aug 29 2013
On 2013-08-30 00:04, "Luís Marques" <luis luismarques.eu>" wrote:On Linux, the following gives out a "multiple definition" error, as expected: c/test.c: void dotest(void) { printf("C\n"); } d/test.d: extern(C) void dotest() { writeln("D"); } On OS X no error is flagged, and the C function is always called, irrespective of which order I specify the .o files to link. Yet, compiling and linking two .c files with a duplication symbol does give an error on the linking phase, as expected. So why the discrepancy? I'm guessing the cause is the section where the symbols appear: On Ubuntu: $ nm d/test.o | grep dotest; echo "--"; nm c/test.o | grep dotest 0000000000000000 T dotest -- 0000000000000000 T dotest On OS X: $ nm d/test.o | grep dotest; echo "--"; nm c/test.o | grep dotest 0000000000001490 S _dotest <-- not in text section, as in Linux -- 0000000000000000 T _dotest 0000000000000060 S _dotest.eh As you might imagine, this situation can be highly disruptive (I'm progressively converting a C application to D). Do you know why the functions appear in the S section on OS X? Do you know of any workaround, to assure that duplicate symbols are correctly flagged?How does it behave on Mac OS X if you just use C? -- /Jacob Carlborg
Aug 29 2013
On Friday, 30 August 2013 at 06:37:07 UTC, Jacob Carlborg wrote:How does it behave on Mac OS X if you just use C?That fails, as expected. (I tried to explain that, I'm sorry if I wasn't clear: )On OS X no error is flagged, and the C function is always called, irrespective of which order I specify the .o files to link. Yet, compiling and linking two .c files with a duplication symbol does give an error on the linking phase, as expected.
Aug 30 2013
On 2013-08-30 16:10, "Luís Marques" <luis luismarques.eu>" wrote:That fails, as expected.So DMD and Clang uses different sections? Have you tried GDC or LDC? -- /Jacob Carlborg
Aug 31 2013
On Saturday, 31 August 2013 at 11:16:11 UTC, Jacob Carlborg wrote:So DMD and Clang uses different sections? Have you tried GDC or LDC?Sorry for the delay. Using LDC fails, as expected / desired: duplicate symbol _dotest in: d/test.o c/test.o ld: 1 duplicate symbol for architecture x86_64 The LDC .o sections are the same as the C version: $ nm d/test.o | grep dotest; echo "--"; nm c/test.o | grep dotest 0000000000000000 T _dotest 00000000000000b0 S _dotest.eh -- 0000000000000000 T _dotest 0000000000000060 S _dotest.eh I haven't tried GDC (I get the object.d not found error, even after installing the D .dmg package, instead of using brew, and I don't recall how I used to solve that), but I imagine it would also fail-work (detect the duplicate symbol, and fail compilation).
Sep 03 2013
On 2013-09-04 00:36, "Luís Marques" <luis luismarques.eu>" wrote:Sorry for the delay. Using LDC fails, as expected / desired: duplicate symbol _dotest in: d/test.o c/test.o ld: 1 duplicate symbol for architecture x86_64 The LDC .o sections are the same as the C version: $ nm d/test.o | grep dotest; echo "--"; nm c/test.o | grep dotest 0000000000000000 T _dotest 00000000000000b0 S _dotest.eh -- 0000000000000000 T _dotest 0000000000000060 S _dotest.eh I haven't tried GDC (I get the object.d not found error, even after installing the D .dmg package, instead of using brew, and I don't recall how I used to solve that), but I imagine it would also fail-work (detect the duplicate symbol, and fail compilation).Perhaps time to file a bug report. I don't know if there's a reason to not use the same sections as C does. http://d.puremagic.com/issues/ -- /Jacob Carlborg
Sep 03 2013
On Wednesday, 4 September 2013 at 06:36:24 UTC, Jacob Carlborg wrote:Perhaps time to file a bug report. I don't know if there's a reason to not use the same sections as C does.I posted it here hoping Walter might comment on this. Maybe he had a good reason to choose a different section. I'll wait a while, and if no feedback is given ("it really has to be a different section because X, Y, Z"), I'll post a bug report.
Sep 04 2013
On Wednesday, 4 September 2013 at 12:41:52 UTC, Luís Marques wrote:I posted it here hoping Walter might comment on this. Maybe he had a good reason to choose a different section. I'll wait a while, and if no feedback is given ("it really has to be a different section because X, Y, Z"), I'll post a bug report.Since Walter did not comment on this, I posted a bug: http://d.puremagic.com/issues/show_bug.cgi?id=11199 I didn't see DMD v2.063.2 in the list of DMD versions, so I chose D2 in the bug report.
Oct 08 2013