Check for OpenMP in configure script is broken

[tian]

The macro AC_TRY_LINK for openMP in configure.in:379 is not working as intended. GCC fails silently while Clang blocks.

The reason is that the second argument to AC_TRY_LINK must not contain the whole main() function
[int main(){do();something();}] but rather its body [do();something();].

​https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.69/html_node/Obsolete-Macros.html#index-AC_005fTRY_005fLINK-2208

[sjoelund.se]

GCC actually allows code like this (except if -Wall -Werror is given; and you won't be able to compile OMC if you use -Werror):

int main() {
  int main() {
    return 1;
  }
  return main();
}

​https://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html ... Too bad it doesn't seem to have a flag to disable it :)

And clang is only an OpenMP compiler if you have clang-3.7 and libomp-dev installed. It also requires linking against libomp, which the configure script does not handle.

[sjoelund.se]

Fixed the reported issue in [71c220705ad90b3b3da205ce9b2dc44f1aaaf942/OMCompiler].

[tian]

Too bad it doesn't seem to have a flag to disable it :)

That's -pedantic-errors. o_O

[dietmarw]

Sorting these closed tickets away from "Future". Since they were closed after the last 1.9.3 release, it's very likely that they should have been part of the 1.9.4 release.

[sjoelund.se]

Milestone renamed

[sjoelund.se]

Milestone renamed