cmake: Minor fixes to handle some CMake specific behavior

Now, all source files are ignored that are not part of the
language of the target. This is also what CMake does.
Additionally it is now supported to build source files that
are generated inside the build directory.

mesonbuild/cmake/interpreter.py

@@ -22,7 +22,7 @@ from ..build import Build
 from ..environment import Environment
 from ..mparser import Token, BaseNode, CodeBlockNode, FunctionNode, ArrayNode, ArgumentNode, AssignmentNode, BooleanNode, StringNode, IdNode, MethodNode
 from ..backend.backends import Backend
-from ..compilers.compilers import obj_suffixes
+from ..compilers.compilers import lang_suffixes, header_suffixes, obj_suffixes
 from ..dependencies.base import CMakeDependency, ExternalProgram
 from subprocess import Popen, PIPE, STDOUT
 from typing import List, Dict, Optional
@@ -57,8 +57,6 @@ target_type_map = {
 
 skip_targets = ['UTILITY']
 
-skip_input_extensions = ['.rule']
-
 blacklist_compiler_flags = [
     '/W1', '/W2', '/W3', '/W4', '/Wall',
     '/O1', '/O2', '/Ob', '/Od', '/Og', '/Oi', '/Os', '/Ot', '/Ox', '/Oy', '/Ob0',
@@ -184,23 +182,37 @@ class ConverterTarget:
         self.link_libraries = temp
 
         # Make paths relative
-        def rel_path(x: str) -> str:
+        def rel_path(x: str, is_header: bool) -> Optional[str]:
             if not os.path.isabs(x):
                 x = os.path.normpath(os.path.join(self.src_dir, x))
+            if not os.path.exists(x) and not any([x.endswith(y) for y in obj_suffixes]):
+                mlog.warning('CMake: path', mlog.bold(x), 'does not exist. Ignoring. This can lead to build errors')
+                return None
+            if os.path.isabs(x) and os.path.commonpath([x, self.env.get_build_dir()]) == self.env.get_build_dir():
+                if is_header:
+                    return os.path.relpath(x, os.path.join(self.env.get_build_dir(), subdir))
+                else:
+                    return os.path.relpath(x, root_src_dir)
             if os.path.isabs(x) and os.path.commonpath([x, root_src_dir]) == root_src_dir:
                 return os.path.relpath(x, root_src_dir)
-            if os.path.isabs(x) and os.path.commonpath([x, self.env.get_build_dir()]) == self.env.get_build_dir():
-                return os.path.relpath(x, os.path.join(self.env.get_build_dir(), subdir))
             return x
 
         build_dir_rel = os.path.relpath(self.build_dir, os.path.join(self.env.get_build_dir(), subdir))
-        self.includes = list(set([rel_path(x) for x in set(self.includes)] + [build_dir_rel]))
-        self.sources = [rel_path(x) for x in self.sources]
-        self.generated = [rel_path(x) for x in self.generated]
-
-        # Filter out CMake rule files
-        self.sources = [x for x in self.sources if not any([x.endswith(y) for y in skip_input_extensions])]
-        self.generated = [x for x in self.generated if not any([x.endswith(y) for y in skip_input_extensions])]
+        self.includes = list(set([rel_path(x, True) for x in set(self.includes)] + [build_dir_rel]))
+        self.sources = [rel_path(x, False) for x in self.sources]
+        self.generated = [rel_path(x, False) for x in self.generated]
+
+        self.includes = [x for x in self.includes if x is not None]
+        self.sources = [x for x in self.sources if x is not None]
+        self.generated = [x for x in self.generated if x is not None]
+
+        # Filter out files that are not supported by the language
+        supported = list(header_suffixes) + list(obj_suffixes)
+        for i in self.languages:
+            supported += list(lang_suffixes[i])
+        supported = ['.{}'.format(x) for x in supported]
+        self.sources = [x for x in self.sources if any([x.endswith(y) for y in supported])]
+        self.generated = [x for x in self.generated if any([x.endswith(y) for y in supported])]
 
         # Make sure '.' is always in the include directories
         if '.' not in self.includes: