distutils: handle unlinkable object files in build_clib/build_ext, not gnu

Add concept of unlinkable Fortran object files on the level of
build_clib/build_ext.

Make build_clib generate fake static libs when unlinkable object files are
present, postponing the actual linkage to build_ext.

This enables MSVC+gfortran DLL chaining to only involve those DLLs that
are actually necessary for each .pyd file, rather than linking everything
in to every file. Linking everything to everywhere has issues due to
potential symbol clashes and the fact that library build order is
unspecified.

Record shared_libs on disk instead of in system_info. This is necessary
for partial builds -- it is not guaranteed the compiler is actually called
for all of the DLL files.

Remove magic from openblas msvc detection. That this worked previously
relied on the side effect that the generated openblas DLL would be added
to shared_libs, and then being linked to all generated outputs.

1 files changed, 32 insertions, 0 deletions

diff --git a/numpy/distutils/fcompiler/__init__.py b/numpy/distutils/fcompiler/__init__.py
index 9d465e9d8..1d558319d 100644
--- a/numpy/distutils/fcompiler/__init__.py
+++ b/numpy/distutils/fcompiler/__init__.py
@@ -698,6 +698,38 @@ class FCompiler(CCompiler):
         else:
             return hook_name()
 
+    def can_ccompiler_link(self, ccompiler):
+        """
+        Check if the given C compiler can link objects produced by
+        this compiler.
+        """
+        return True
+
+    def wrap_unlinkable_objects(self, objects, output_dir, extra_dll_dir):
+        """
+        Convert a set of object files that are not compatible with the default
+        linker, to a file that is compatible.
+
+        Parameters
+        ----------
+        objects : list
+            List of object files to include.
+        output_dir : str
+            Output directory to place generated object files.
+        extra_dll_dir : str
+            Output directory to place extra DLL files that need to be
+            included on Windows.
+
+        Returns
+        -------
+        converted_objects : list of str
+             List of converted object files.
+             Note that the number of output files is not necessarily
+             the same as inputs.
+
+        """
+        raise NotImplementedError()
+
     ## class FCompiler
 
 _default_compilers = (