{"id":347,"date":"2012-04-28T08:33:18","date_gmt":"2012-04-28T08:33:18","guid":{"rendered":"http:\/\/blog.bachi.net\/?p=347"},"modified":"2012-04-28T08:46:36","modified_gmt":"2012-04-28T08:46:36","slug":"mingw-unix-incompatible-compile-verbose","status":"publish","type":"post","link":"https:\/\/blog.bachi.net\/?p=347","title":{"rendered":"MingW: UNIX incompatible & compile verbose"},"content":{"rendered":"

Building Mingw executables using Cygwin<\/a><\/p>\n

One particular vexing source of error is when you include a file that
\nexists for Cygwin, but not for Mingw32; the compilation goes ok, but
\nthe compiler is really using the *WRONG* include file and you get link
\ntime errors.<\/p>\n

Let’s say you have some code that uses the POSIX\/BSD “times” function
\nwhich is not part of the ANSI standard and does not exist under Mingw32
\nruntime.<\/p>\n

\r\n  #include\r\n  #include\r\n  int main () {\r\n      struct tms time_info;\r\n      times (&time_info);\r\n      printf ("user_time = %d, system_time = %d\\n",\r\n              time_info.tms_utime, time_info.tms_stime);\r\n      return 0;\r\n  }\r\n<\/pre>\n
Now build the “times” program:<\/p>\n
\r\n  $ gcc -c -mno-cygwin times.c\r\n  $ gcc -o times -mno-cygwin times.o\r\n  times.o(.text+0x34):times.c: undefined reference to `times'\r\n  collect2: ld returned 1 exit status\r\n<\/pre>\n
Notice that the compilation goes just fine, but you get an undefined
\nreference to the “times” function.<\/p>\n
What happens is that Cygwin first looks in the mingw32 include directory
\nthe <sys\/times.h><\/code> file and it can’t find it; it then looks at the default
\ndirectory and does find it and uses it and everything is fine at this
\npoint. However, at link time, the Mingw32 runtime library lacks this
\nfunction and you get an undefined error. Sometimes these are so confusing
\nthat you may get sidetracked and not look at the real source of the
\nproblem — your own code!<\/p>\n
So, how do you diagnose these errors? Whenever you get such errors, use
\nthe -v<\/code> (verbose) and -H<\/code> (show include files) options when compiling
\nto see where include files are coming from. Then use -v<\/code> option when
\nlinking to see what libraries are being linked in.<\/p>\n
Another source of error is creating Mingw DLLs using dllwrap. The current
\nversion of dllwrap<\/code> does not know the -mno-cygwin<\/code> option and will
\nincorrectly add Cygwin libraries when creating DLLs. The workaround is
\nquite simple: add the --target=i386-mingw32<\/code> option instead. In the future,
\ndllwrap<\/code> will simply translate the -mno-cygwin<\/code> option to the --target<\/code>
\noption and it will just work.<\/p>\n","protected":false},"excerpt":{"rendered":"
Building Mingw executables using Cygwin One particular vexing source of error is when you include a file that exists for Cygwin, but not for Mingw32; the compilation goes ok, but the compiler is really using the *WRONG* include file and you get link time errors. Let’s say you have some code that uses the POSIX\/BSD […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-347","post","type-post","status-publish","format-standard","hentry","category-mingw"],"_links":{"self":[{"href":"https:\/\/blog.bachi.net\/index.php?rest_route=\/wp\/v2\/posts\/347","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.bachi.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.bachi.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.bachi.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.bachi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=347"}],"version-history":[{"count":10,"href":"https:\/\/blog.bachi.net\/index.php?rest_route=\/wp\/v2\/posts\/347\/revisions"}],"predecessor-version":[{"id":359,"href":"https:\/\/blog.bachi.net\/index.php?rest_route=\/wp\/v2\/posts\/347\/revisions\/359"}],"wp:attachment":[{"href":"https:\/\/blog.bachi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=347"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.bachi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=347"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.bachi.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=347"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}