Bug 1375798 - Figure out host library/object prefix/suffixes and use them for libclang. r=mshal

The libclang test wants to find a libclang library for use for rust bindgen.
But that's a host process, that needs a host libclang. However, we
currently only have the target library/object prefix/suffixes. This
works fine... except when cross-compiling.

So we need to figure out the proper ones for the host, and use those
instead. For that, we templatize library_name_info in order to get a
separate set of library/object prefix/suffixes for the host and the
target.

And we use the host set for the libclang check.

Ideally, the build system would also use the host set for host tools
builds, but we'll leave that to a followup.

--HG--
extra : rebase_source : 1970791d6d5f9b3f79fbe34b7e3d05dd4b5c3f7b

moz.configure

@@ -143,9 +143,10 @@ include('build/moz.configure/headers.configure',
 include('build/moz.configure/warnings.configure',
         when='--enable-compile-environment')
 
-@depends(target)
-def is_openbsd(target):
-    return target.kernel == 'OpenBSD'
+
+@depends(target, host)
+def is_openbsd(target, host):
+    return target.kernel == 'OpenBSD' or host.kernel == 'OpenBSD'
 
 option(env='SO_VERSION', nargs=1, default='1.0', when=is_openbsd,
        help='Shared library version for OpenBSD systems')
@@ -154,48 +155,61 @@ option(env='SO_VERSION', nargs=1, default='1.0', when=is_openbsd,
 def so_version(value):
     return value
 
-@depends(target, c_compiler, so_version)
-def library_name_info(target, c_compiler, so_version):
-    if target.kernel == 'WINNT':
-        # There aren't artifacts for mingw builds, so it's OK that the results
-        # are inaccurate in that case.
-        if c_compiler and c_compiler.type not in ('msvc', 'clang-cl'):
+@template
+def library_name_info_template(host_or_target):
+    assert host_or_target in (host, target)
+    compiler = {
+        host: host_c_compiler,
+        target: c_compiler,
+    }[host_or_target]
+
+    @depends(host_or_target, compiler, so_version)
+    def library_name_info_impl(host_or_target, compiler, so_version):
+        if host_or_target.kernel == 'WINNT':
+            # There aren't artifacts for mingw builds, so it's OK that the
+            # results are inaccurate in that case.
+            if compiler and compiler.type not in ('msvc', 'clang-cl'):
+                return namespace(
+                    dll=namespace(prefix='', suffix='.dll'),
+                    lib=namespace(prefix='lib', suffix='a'),
+                    import_lib=namespace(prefix='lib', suffix='a'),
+                    rust_lib=namespace(prefix='', suffix='lib'),
+                    obj=namespace(prefix='', suffix='o'),
+                )
+
             return namespace(
                 dll=namespace(prefix='', suffix='.dll'),
-                lib=namespace(prefix='lib', suffix='a'),
-                import_lib=namespace(prefix='lib', suffix='a'),
+                lib=namespace(prefix='', suffix='lib'),
+                import_lib=namespace(prefix='', suffix='lib'),
                 rust_lib=namespace(prefix='', suffix='lib'),
-                obj=namespace(prefix='', suffix='o'),
+                obj=namespace(prefix='', suffix='obj'),
             )
 
-        return namespace(
-            dll=namespace(prefix='', suffix='.dll'),
-            lib=namespace(prefix='', suffix='lib'),
-            import_lib=namespace(prefix='', suffix='lib'),
-            rust_lib=namespace(prefix='', suffix='lib'),
-            obj=namespace(prefix='', suffix='obj'),
-        )
+        elif host_or_target.kernel == 'Darwin':
+            return namespace(
+                dll=namespace(prefix='lib', suffix='.dylib'),
+                lib=namespace(prefix='lib', suffix='a'),
+                import_lib=namespace(prefix=None, suffix=''),
+                rust_lib=namespace(prefix='lib', suffix='a'),
+                obj=namespace(prefix='', suffix='o'),
+            )
+        elif so_version:
+            so = '.so.%s' % so_version
+        else:
+            so = '.so'
 
-    elif target.kernel == 'Darwin':
         return namespace(
-            dll=namespace(prefix='lib', suffix='.dylib'),
+            dll=namespace(prefix='lib', suffix=so),
             lib=namespace(prefix='lib', suffix='a'),
             import_lib=namespace(prefix=None, suffix=''),
             rust_lib=namespace(prefix='lib', suffix='a'),
             obj=namespace(prefix='', suffix='o'),
         )
-    elif so_version:
-        so = '.so.%s' % so_version
-    else:
-        so = '.so'
 
-    return namespace(
-        dll=namespace(prefix='lib', suffix=so),
-        lib=namespace(prefix='lib', suffix='a'),
-        import_lib=namespace(prefix=None, suffix=''),
-        rust_lib=namespace(prefix='lib', suffix='a'),
-        obj=namespace(prefix='', suffix='o'),
-    )
+    return library_name_info_impl
+
+host_library_name_info = library_name_info_template(host)
+library_name_info = library_name_info_template(target)
 
 set_config('DLL_PREFIX', library_name_info.dll.prefix)
 set_config('DLL_SUFFIX', library_name_info.dll.suffix)

toolkit/moz.configure

@@ -696,7 +696,7 @@ with only_when(building_stylo_bindgen):
             '''.format(version, min_version)))
 
     @depends(llvm_config, '--with-libclang-path', '--with-clang-path',
-             library_name_info, host)
+             host_library_name_info, host)
     @imports('os.path')
     @imports(_from='textwrap', _import='dedent')
     def bindgen_config_paths(llvm_config, libclang_path, clang_path,