Linker inherits CompilerWrapper (#20)

[lukehoffmann]

Changes Linker to inherit CompilerWrapper as in Issue #20

[lukehoffmann]

Was this test previously meant to mock LDFLAGS or FFLAGS?

[hiker]

Leave this for now. I need a decision from the Fab devs if we can abandon support for environment variables (Fab should be free of that, any application ... like the Fab build system can decide to support this and provide the appropriate flags based on environment variables).

[lukehoffmann]

Was this test previously meant to mock LDFLAGS or FFLAGS?

[hiker]

Same, imho this should all go.

[lukehoffmann]

This was my work on issue #20 before I saw the new comment about reusing flags with mpi wrappers.

Have a look and see if it would be useful in its current form.

[hiker]

Seems to go in the right direction. But we need to support nested linker - e.g. an intel mpif90 wrapper would need to take a linker (which is now a CompilerWrapper) - linker-ifort as parameter. Then any flags from linker-ifort need to he used in the intel-mpif90 wrapper. I am not sure about the best way to implement this, here some tests with using isinstance:

joerg@Joerg-Surface:~/work/fab/source/fab/tools$ git diff ./linker.py
diff --git a/source/fab/tools/linker.py b/source/fab/tools/linker.py
index 1256ff3..7c60066 100644
--- a/source/fab/tools/linker.py
+++ b/source/fab/tools/linker.py
@@ -55,6 +55,8 @@ class Linker(CompilerWrapper):
         try:
             return self._lib_flags[lib]
         except KeyError:
+            if isinstance(self.compiler, Linker):
+                return self._compiler.get_lib_flags(lib)
             raise RuntimeError(f"Unknown library name: '{lib}'")
 
     def add_lib_flags(self, lib: str, flags: List[str],
@@ -112,6 +114,8 @@ class Linker(CompilerWrapper):
         :returns: the stdout of the link command
         '''
         # Don't need to add compiler's flags, they are added by CompilerWrapper.
+        if isinstance(self.compiler, Linker):
+            print("RECURSIVE")
         params: List[Union[str, Path]] = []
         if openmp:
             params.append(self._compiler.openmp_flag)

So the first modification (to get_lib_flags) should work just fine - if we don't have a defintion (which could overwrite the base linker), and the 'compiler' is a linker, we call it to get the definition.

The second modification needs a bit more work. For now I'd guess that any pre- and post-flags from the linker wrapper should wrap the linker ... that sounds convoluted. Assume linker1 adds pre1 and post1, and linker 2 adds pre2 and post2. If linker2 - Linker(linker1), then we should get:

pre2  pre1  <libraryflags> post1 post2

Is that enough to get you started?

[hiker]

Luke will not have time to finish this