[WIP] Start fixing include paths

mesonbuild/backend/ninjabackend.py

@@ -2784,28 +2784,6 @@ def generate_llvm_ir_compile(self, target, src):
         self.add_build(element)
         return (rel_obj, rel_src)
 
-    @lru_cache(maxsize=None)
-    def generate_inc_dir(self, compiler: 'Compiler', d: str, basedir: str, is_system: bool) -> \
-            T.Tuple['ImmutableListProtocol[str]', 'ImmutableListProtocol[str]']:
-        # Avoid superfluous '/.' at the end of paths when d is '.'
-        if d not in ('', '.'):
-            expdir = os.path.normpath(os.path.join(basedir, d))
-        else:
-            expdir = basedir
-        srctreedir = os.path.normpath(os.path.join(self.build_to_src, expdir))
-        sargs = compiler.get_include_args(srctreedir, is_system)
-        # There may be include dirs where a build directory has not been
-        # created for some source dir. For example if someone does this:
-        #
-        # inc = include_directories('foo/bar/baz')
-        #
-        # But never subdir()s into the actual dir.
-        if os.path.isdir(os.path.join(self.environment.get_build_dir(), expdir)):
-            bargs = compiler.get_include_args(expdir, is_system)
-        else:
-            bargs = []
-        return (sargs, bargs)
-
     def _generate_single_compile(self, target: build.BuildTarget, compiler: Compiler) -> CompilerArgs:
         commands = self._generate_single_compile_base_args(target, compiler)
         commands += self._generate_single_compile_target_args(target, compiler)
@@ -2848,11 +2826,11 @@ def _generate_single_compile_target_args(self, target: build.BuildTarget, compil
             # We should iterate include dirs in reversed orders because
             # -Ipath will add to begin of array. And without reverse
             # flags will be added in reversed order.
-            for d in reversed(i.get_incdirs()):
+            for d in reversed(i.expand_incdirs(self.environment.get_build_dir())):
                 # Add source subdir first so that the build subdir overrides it
-                (compile_obj, includeargs) = self.generate_inc_dir(compiler, d, basedir, i.is_system)
-                commands += compile_obj
-                commands += includeargs
+                commands += compiler.get_include_args(os.path.normpath(os.path.join(self.build_to_src, d.srcdir)), i.is_system)
+                if d.builddir is not None:
+                    commands += compiler.get_include_args(d.builddir, i.is_system)
             for d in i.get_extra_build_dirs():
                 commands += compiler.get_include_args(d, i.is_system)
         # Add per-target compile args, f.ex, `c_args : ['-DFOO']`. We set these

mesonbuild/build.py

@@ -449,9 +449,45 @@ def get_curdir(self) -> str:
     def get_incdirs(self) -> T.List[str]:
         return self.incdirs
 
+    def expand_incdirs(self, builddir: str) -> T.List[IncludeDirPair]:
+        result = []
+
+        curdir = self.curdir
+        bsubdir = compute_build_subdir(curdir, self.is_build_only_subproject)
+        for d in self.incdirs:
+            # Avoid superfluous '/.' at the end of paths when d is '.'
+            if d not in ('', '.'):
+                sdir = os.path.normpath(os.path.join(curdir, d))
+                bdir = os.path.normpath(os.path.join(bsubdir, d))
+            else:
+                sdir = curdir
+                bdir = bsubdir
+
+            # There may be include dirs where a build directory has not been
+            # created for some source dir. For example if someone does this:
+            #
+            # inc = include_directories('foo/bar/baz')
+            #
+            # But never subdir()s into the actual dir.
+            if not os.path.isdir(os.path.join(builddir, bdir)):
+                bdir = None
+
+            result.append(IncludeDirPair(sdir, bdir))
+
+        return result
+
     def get_extra_build_dirs(self) -> T.List[str]:
         return self.extra_build_dirs
 
+    def expand_extra_build_dirs(self) -> T.List[str]:
+        result = []
+
+        bsubdir = compute_build_subdir(self.curdir, self.is_build_only_subproject)
+        for d in self.extra_build_dirs:
+            result.append(os.path.normpath(os.path.join(bsubdir, d)))
+
+        return result
+
     def to_string_list(self, sourcedir: str, builddir: str) -> T.List[str]:
         """Convert IncludeDirs object to a list of strings.
 
@@ -468,6 +504,11 @@ def to_string_list(self, sourcedir: str, builddir: str) -> T.List[str]:
             strlist.append(os.path.join(builddir, bsubdir, idir))
         return strlist
 
+@dataclass
+class IncludeDirPair:
+    srcdir: str
+    builddir: T.Optional[str]
+
 @dataclass(eq=False)
 class ExtractedObjects(HoldableObject):
     '''