Testsuite breakages on Cygwin

[Jonathan Wakely]

On 10 March 2017 at 06:39, Daniel Santos wrote:
> Hello,
>
> I've been trying to get some clean test results on Cygwin and have
> encountered a number of problems.  I've opened a report for the one I'm most
> concerned with (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79867). When an
> executable is being loaded, Windows searches for dlls based upon a few silly
> ms-like rules (https://msdn.microsoft.com/en-us/library/7d83bc18.aspx),
> followed by the PATH environment variable.  LD_LIBRARY_PATH is only used in
> Cygwin when loading a dll at run-time via dlopen().  This means that ALL
> tests are performed by linking in the shared libs that are installed on the
> *system* and not those built in the bootstrap.  If the dll is not installed
> on the system then the test fails.  Example:
>
> FAIL: gfortran.dg/coarray/sync_3.f90 -fcoarray=single  -O2   output pattern
> test, is
> D:/builds/head-test-moutline-x86_64-pc-cygwin/gcc/testsuite/gfortran/sync_3.exe:
> error while loading shared libraries: cyggfortran-4.dll: cannot open shared
> object file: No such file or directory

This is the cause of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66530