Add warning for unused imports

blueprintcompiler/language/common.py

@@ -35,6 +35,7 @@ from ..errors import (
     CompileWarning,
     DeprecatedWarning,
     MultipleErrors,
+    UnusedWarning,
     UpgradeWarning,
 )
 from ..gir import (

blueprintcompiler/language/imports.py

@@ -88,6 +88,17 @@ class Import(AstNode):
     def namespace_exists(self):
         gir.get_namespace(self.tokens["namespace"], self.tokens["version"])
 
+    @validate()
+    def unused(self):
+        if self.namespace not in self.root.used_imports:
+            raise UnusedWarning(
+                f"Unused import: {self.namespace}",
+                self.range,
+                actions=[
+                    CodeAction("Remove import", "", self.range.with_trailing_newline)
+                ],
+            )
+
     @property
     def gir_namespace(self):
         try:

blueprintcompiler/language/types.py

@@ -78,9 +78,10 @@ class TypeName(AstNode):
             )
 
     @property
-    def gir_ns(self):
+    def gir_ns(self) -> T.Optional[gir.Namespace]:
         if not self.tokens["extern"]:
             return self.root.gir.namespaces.get(self.tokens["namespace"] or "Gtk")
+        return None
 
     @property
     def gir_type(self) -> gir.GirType:

blueprintcompiler/language/ui.py

@@ -27,6 +27,7 @@ from .gtk_menu import Menu, menu
 from .gtkbuilder_template import Template
 from .imports import GtkDirective, Import
 from .translation_domain import TranslationDomain
+from .types import TypeName
 
 
 class UI(AstNode):
@@ -121,6 +122,22 @@ class UI(AstNode):
             Range(pos, pos, self.group.text),
         )
 
+    @cached_property
+    def used_imports(self) -> T.Optional[T.Set[str]]:
+        def _iter_recursive(node: AstNode):
+            yield node
+            for child in node.children:
+                if isinstance(child, AstNode):
+                    yield from _iter_recursive(child)
+
+        result = set()
+        for node in _iter_recursive(self):
+            if isinstance(node, TypeName):
+                ns = node.gir_ns
+                if ns is not None:
+                    result.add(ns.name)
+        return result
+
     @context(ScopeCtx)
     def scope_ctx(self) -> ScopeCtx:
         return ScopeCtx(node=self)