Add warning for unused imports

blueprintcompiler/ast_utils.py

@@ -125,7 +125,7 @@ class AstNode:
             return self.parent.root
 
     @property
-    def range(self):
+    def range(self) -> Range:
         return Range(self.group.start, self.group.end, self.group.text)
 
     def parent_by_type(self, type: T.Type[TType]) -> TType:

blueprintcompiler/errors.py

@@ -140,6 +140,10 @@ class DeprecatedWarning(CompileWarning):
     pass
 
 
+class UnusedWarning(CompileWarning):
+    pass
+
+
 class UpgradeWarning(CompileWarning):
     category = "upgrade"
     color = Colors.PURPLE

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)

blueprintcompiler/lsp.py

@@ -475,6 +475,9 @@ class LanguageServer:
         if isinstance(err, DeprecationWarning):
             result["tags"] = [DiagnosticTag.Deprecated]
 
+        if isinstance(err, UnusedWarning):
+            result["tags"] = [DiagnosticTag.Unnecessary]
+
         if len(err.references) > 0:
             result["relatedInformation"] = [
                 {

blueprintcompiler/tokenizer.py

@@ -127,6 +127,13 @@ class Range:
     def text(self) -> str:
         return self.original_text[self.start : self.end]
 
+    @property
+    def with_trailing_newline(self) -> "Range":
+        if len(self.original_text) > self.end and self.original_text[self.end] == "\n":
+            return Range(self.start, self.end + 1, self.original_text)
+        else:
+            return self
+
     @staticmethod
     def join(a: T.Optional["Range"], b: T.Optional["Range"]) -> T.Optional["Range"]:
         if a is None:

tests/sample_errors/deprecations.blp

@@ -1,5 +1,4 @@
 using Gtk 4.0;
-using Gio 2.0;
 
 Dialog {
   use-header-bar: 1;

tests/sample_errors/deprecations.err

@@ -1 +1 @@
-4,1,6,Gtk.Dialog is deprecated
+3,1,6,Gtk.Dialog is deprecated

tests/sample_errors/warn_unused_import.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+using GLib 2.0;
+using Gio 2.0;
+
+Gio.Cancellable {}

tests/sample_errors/warn_unused_import.err

@@ -0,0 +1 @@
+2,1,15,Unused import: GLib

tests/samples/parseable.blp

@@ -1,5 +1,4 @@
 using Gtk 4.0;
-using Gio 2.0;
 
 Gtk.Shortcut {
   trigger: "Escape";