Re: Fwd: gcc does not honor -fno-leading-underscore flag?
Brian Dessent wrote: [EMAIL PROTECTED] wrote: I do not know how to get rid of the leading underscores in Cygwin. I have other sources compiled in Linux, and they do not have a leading underscore added. As I understand it, the -fleading-underscore flag is only useful to add a leading underscore for targets that do not have a leading underscore, like linux. It won't accomplish anything on one that already has it, like PE. You may be right. But then this is strange for me. I would guess that either -fleading-underscore or -fno-leading-underscore do something, but not both doing nothing. So if a target does have a leading underscore and then -fleading-underscore does nothing on it (according to what you say), then I would expect -fno-leading-underscore removing the underscore. Now my problem is that I have a library with symbol names without a leading underscore. Although the library is for Linux (I do not have a version specific for Cygwin, which would be the ideal solution, and I do not think that I could get it; I don't have the sources), I expect it to work under Cygwin (or at least give it a try), if only I could get my objects to link with its symbols. Even if I am trying to mix objects for different platforms, I guess that there should be a chance to do it by appropriate configuration. The flag -fno-leading-underscore seemed to be the answer, but it did not work for me. There is absolutely no way that you can use an object compiled for Linux with Cygwin. The fact that symbols don't have a leading underscore is trivial compared to the massive differences between ELF and PE formats. There is just no chance of this working even if you solved the underscore issue. I suspected this, but I was not sure. I do not know what is ELF and PE... I though about trying since I have Windows apps that work on Cygwin, but possibly they are much more similar. Thanks a lot. Santiago Brian -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: Fwd: gcc does not honor -fno-leading-underscore flag?
[EMAIL PROTECTED] wrote: You may be right. But then this is strange for me. I would guess that either -fleading-underscore or -fno-leading-underscore do something, but not both doing nothing. So if a target does have a leading underscore and then -fleading-underscore does nothing on it (according to what you say), then I would expect -fno-leading-underscore removing the underscore. Adding an extra underscore on a platform that doesn't have one isn't doing anything that you couldn't equivalently accomplish at the source level, so it's not really violating any ABIs. However, removing the underscore when the platform spec says that all symbols must have a leading underscore prepended would violate the ABI, and there is no way[1] to achieve the equivalent thing at the source level so this is a much more dangerous proposition. That is the intent of the switch; it is not designed for what you're trying to make it do. I suspected this, but I was not sure. I do not know what is ELF and PE... I though about trying since I have Windows apps that work on Cygwin, but possibly they are much more similar. I think you are confused about what Cygwin is. It is not a binary emulator of any kind, it is a Win32 library just like any other DLL. All Cygwin apps are standard Win32 executables/libraries, there is no difference as far as the operating system is concerned. The reason you cannot use an object compiled with a Linux compiler is because Linux uses an entirely different binary format and ABI. Even though they may run on the same identical hardware, the details of how things work at the assembler and linker level are significantly different. The fact that it's gcc on both sides doesn't change anything, because gcc's behavior is determined entirely by the target it was configured for; two gccs of different targets are essentially two totally different compilers. Brian [1] well technically it's possible using __asm__() but that's an extension and not standard C. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: Fwd: gcc does not honor -fno-leading-underscore flag?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 According to [EMAIL PROTECTED] on 4/23/2008 8:27 AM: | As I understand it, the -fleading-underscore flag is only useful to add | a leading underscore for targets that do not have a leading underscore, | like linux. It won't accomplish anything on one that already has it, | like PE. | | You may be right. But then this is strange for me. I would guess that | either -fleading-underscore or -fno-leading-underscore do something, but | not both doing nothing. I look at it this way: -fleading-underscore adds an underscore on platforms where it is not necessary (and is a no-op on platforms where leading underscore is already required); -fno-leading-underscore undoes the effect of an earlier -fleading-underscore (removes the underscore where possible, and is a no-op on platforms like cygwin where it is not possible). - -- Don't work too hard, make some time for fun as well! Eric Blake [EMAIL PROTECTED] -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (Cygwin) Comment: Public key at home.comcast.net/~ericblake/eblake.gpg Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkgP/nsACgkQ84KuGfSFAYCnXgCePRD9+U8AZusRmgRqWeBjhtmK sEEAn3hHttMrUCi21Ch13oC7aL5fZJL5 =pizv -END PGP SIGNATURE- -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Fwd: gcc does not honor -fno-leading-underscore flag?
Hi, I have been scratching my head for a while... to no avail. I have compiled a simple source file with and without -fno-leading-underscore flag, and the objects generated seem to have exactly the same names for all symbols, always having a leading underscore. What I do: 1- Compile the source underscores.c (see below), with two different command lines $ gcc -g -g3 -Wall -Wextra -Wunused -Wuninitialized -Wfloat-equal -Wundef -Wshadow underscores.c -o underscores.exe and $ gcc -g -g3 -Wall -Wextra -Wunused -Wuninitialized -Wfloat-equal -Wundef -Wshadow underscores.c -o underscores.exe -fno-leading-underscore 2- Obtain the symbols in each of the objects generated. 3- Diff them. The result is that there are no differences. The complete list of symbols is shown below. It is worth noting that the function f1 defined in underscores.c has _f1 as its symbol name. I do not know how to get rid of the leading underscores in Cygwin. I have other sources compiled in Linux, and they do not have a leading underscore added. Now my problem is that I have a library with symbol names without a leading underscore. Although the library is for Linux (I do not have a version specific for Cygwin, which would be the ideal solution, and I do not think that I could get it; I don't have the sources), I expect it to work under Cygwin (or at least give it a try), if only I could get my objects to link with its symbols. Even if I am trying to mix objects for different platforms, I guess that there should be a chance to do it by appropriate configuration. The flag -fno-leading-underscore seemed to be the answer, but it did not work for me. Any hints? Thanks a lot. --- output of $ nm underscores.exe --- 00403020 b .bss 00403000 b .bss 00403010 b .bss 00403020 b .bss 00403020 b .bss 00403020 b .bss 00403010 b .bss 00403020 b .bss 00403020 b .bss 00403020 b .bss 00403020 b .bss 00403010 b .bss 00403020 b .bss 00403010 b .bss U .data U .data U .data U .data U .data U .data U .data U .data U .data U .data U .data U .data U .data U .data 00404014 i .idata$2 00404000 i .idata$2 0040406c i .idata$4 00404064 i .idata$4 0040403c i .idata$4 00404040 i .idata$4 00404058 i .idata$4 0040405c i .idata$4 00404050 i .idata$4 00404068 i .idata$4 00404044 i .idata$4 0040404c i .idata$4 00404048 i .idata$4 00404060 i .idata$4 00404054 i .idata$4 00404070 i .idata$4 00404098 i .idata$5 0040409c i .idata$5 004040a4 i .idata$5 00404088 i .idata$5 00404074 i .idata$5 00404080 i .idata$5 00404094 i .idata$5 004040a8 i .idata$5 0040407c i .idata$5 0040408c i .idata$5 00404078 i .idata$5 00404084 i .idata$5 004040a0 i .idata$5 00404090 i .idata$5 00404130 i .idata$6 004040ac i .idata$6 004040d4 i .idata$6 00404104 i .idata$6 004040c8 i .idata$6 004040b8 i .idata$6 0040410c i .idata$6 00404124 i .idata$6 004040e8 i .idata$6 00404118 i .idata$6 0040415c i .idata$7 00404168 i .idata$7 00404144 i .idata$7 00404160 i .idata$7 00404154 i .idata$7 00404148 i .idata$7 0040414c i .idata$7 00404164 i .idata$7 00404158 i .idata$7 00404178 i .idata$7 00404150 i .idata$7 00404174 i .idata$7 00402000 r .rdata 00405000 N .stab 004013b8 t .text 00401390 t .text 00401350 t .text 00401340 t .text 004013a0 t .text 00401000 t .text 00401330 t .text 00401320 t .text 004012c0 t .text 004013b0 t .text 004012c0 t .text 004012b0 t .text 00401160 t .text 00401150 t .text 00401140 t .text 004010e0 t .text 004010b0 t .text 004013b8 t .text 00401380 t .text 004013c0 t .text 00401360 t .text 00401050 t .text 00401370 t .text 004013b0 T [EMAIL PROTECTED] 00401000 T _WinMainCRTStartup 004013c0 T __CTOR_LIST__ 004013c8 T __DTOR_LIST__ 00402020 R __RUNTIME_PSEUDO_RELOC_LIST_END__ 00402020 R __RUNTIME_PSEUDO_RELOC_LIST__ 004013c0 T ___CTOR_LIST__ 004013c8 T ___DTOR_LIST__ 00402020 R ___RUNTIME_PSEUDO_RELOC_LIST_END__ 00402020 R ___RUNTIME_PSEUDO_RELOC_LIST__ 004010b0 T ___chkstk 00405000 A ___crt_xc_end__ 00405000 A ___crt_xc_start__ 00405000 A ___crt_xi_end__ 00405000 A ___crt_xi_start__ 00405000 A ___crt_xl_start__ 00405000 A ___crt_xp_end__ 00405000 A ___crt_xp_start__ 00405000 A ___crt_xt_end__ 00405000 A ___crt_xt_start__ 00403000 B ___cygwin_crt0_bp 00401140 T ___main 00405000 A ___tls_end__ 00405000 A ___tls_start__ 004010b0 T __alloca 00403040 B __bss_end__ 00403000 B __bss_start__ 00401160 T [EMAIL PROTECTED] 00402000 A __data_end__ 00402000 A __data_start__ A __dll__ 00405000 A __end__ 0200 A __file_alignment__ 00403010 B __fmode 00404000 I __head_cygwin1_dll 00404014 I __head_libkernel32_a 0040 A __image_base__ 004040a4 I [EMAIL PROTECTED] 00404078 I __impmain 0040407c I __imp___impure_ptr 00404080 I __imp__calloc 00404084 I __imp__cygwin_internal 00404088 I __imp__dll_crt0__FP11per_process 0040408c I __imp__free 00404090 I __imp__malloc
Re: Fwd: gcc does not honor -fno-leading-underscore flag?
[EMAIL PROTECTED] wrote: I do not know how to get rid of the leading underscores in Cygwin. I have other sources compiled in Linux, and they do not have a leading underscore added. As I understand it, the -fleading-underscore flag is only useful to add a leading underscore for targets that do not have a leading underscore, like linux. It won't accomplish anything on one that already has it, like PE. Now my problem is that I have a library with symbol names without a leading underscore. Although the library is for Linux (I do not have a version specific for Cygwin, which would be the ideal solution, and I do not think that I could get it; I don't have the sources), I expect it to work under Cygwin (or at least give it a try), if only I could get my objects to link with its symbols. Even if I am trying to mix objects for different platforms, I guess that there should be a chance to do it by appropriate configuration. The flag -fno-leading-underscore seemed to be the answer, but it did not work for me. There is absolutely no way that you can use an object compiled for Linux with Cygwin. The fact that symbols don't have a leading underscore is trivial compared to the massive differences between ELF and PE formats. There is just no chance of this working even if you solved the underscore issue. Brian -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
