Needless operation lint should ignore lambdas (#2406)

Fixes #2039

Author: swernli

compiler/qsc_linter/src/lints/hir.rs

@@ -161,7 +161,7 @@ impl HirLintPass for NeedlessOperation {
         buffer: &mut Vec<Lint>,
         _compilation: Compilation,
     ) {
-        if decl.kind == CallableKind::Operation {
+        if decl.kind == CallableKind::Operation && &*decl.name.name != "<lambda>" {
             let mut op_limits = IsQuantumOperation::default();
 
             op_limits.visit_callable_decl(decl);

compiler/qsc_linter/src/tests.rs

@@ -433,19 +433,11 @@ fn redundant_semicolons() {
 }
 
 #[test]
-fn needless_operation_lambda_operations() {
+fn needless_operation_no_lint_for_lambda_operations() {
     check(
         &wrap_in_callable("let a = (a) => a + 1;", CallableKind::Function),
         &expect![[r#"
-            [
-                SrcLint {
-                    source: "(a) => a + 1",
-                    level: Allow,
-                    message: "operation does not contain any quantum operations",
-                    help: "this callable can be declared as a function instead",
-                    code_action_edits: [],
-                },
-            ]
+            []
         "#]],
     );
 }
@@ -557,6 +549,7 @@ fn needless_operation_partial_application() {
         "#]],
     );
 }
+
 #[test]
 fn deprecated_newtype_usage() {
     check(