fix literal_only_boolean_expressions if-case false positives (dart-archive/linter#4355)

Author: pq

lib/src/rules/literal_only_boolean_expressions.dart

@@ -160,6 +160,7 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitIfStatement(IfStatement node) {
+    if (node.caseClause != null) return;
     if (_onlyLiterals(node.expression)) {
       rule.reportLint(node);
     }

test/rules/literal_only_boolean_expressions_test.dart

@@ -36,6 +36,77 @@ class LiteralOnlyBooleanExpressionsTestLanguage300 extends LintRuleTest
   @override
   String get lintRule => 'literal_only_boolean_expressions';
 
+  test_ifCase_intLiteral() async {
+    await assertDiagnostics(r'''
+void f() {
+  if (1 case {1:0}) {
+    print('');
+  }
+}
+''', [
+      // No lint
+      error(WarningCode.PATTERN_NEVER_MATCHES_VALUE_TYPE, 24, 5),
+    ]);
+  }
+
+  test_ifCase_listLiteral() async {
+    await assertNoDiagnostics(r'''
+void f() {
+  if ([1] case [1]) {
+    print('');
+  }
+}
+''');
+  }
+
+  test_ifCase_mapLiteral() async {
+    await assertNoDiagnostics(r'''
+void f() {
+  if ({1:0} case {1:0}) {
+    print('');
+  }
+}
+''');
+  }
+
+  test_ifCase_objectInstantiation() async {
+    await assertNoDiagnostics(r'''
+class A {
+  final int a;
+  A(this.a);
+}
+
+void f() {
+  if (A(1) case A(a: 1)) {
+    print('');
+  }
+}
+''');
+  }
+
+  /// https://github.com/dart-lang/linter/issues/4352
+  test_ifCase_record() async {
+    await assertNoDiagnostics(r'''
+void f() {
+  if (('', '') case (String(), String())) {
+    print('');
+  }
+}
+''');
+  }
+
+  test_switchExpression() async {
+    await assertNoDiagnostics(r'''
+bool f(Object o) => switch(o) {
+    [1] => true,
+    {1:1} => false,
+    (1, 1) => false,
+    String(isEmpty: false) => false,
+    _ => false,
+  };
+''');
+  }
+
   test_whenClause() async {
     await assertDiagnostics(r'''
 void f() {