feat(linter/strict-boolean-expression): add rule

Author: camc314

apps/oxlint/fixtures/tsgolint/.oxlintrc.json

@@ -39,6 +39,7 @@
     "typescript/restrict-plus-operands": "error",
     "typescript/restrict-template-expressions": "error",
     "typescript/return-await": "error",
+    "typescript/strict-boolean-expressions": "error",
     "typescript/switch-exhaustiveness-check": "error",
     "typescript/unbound-method": "error",
     "typescript/use-unknown-in-catch-callback-variable": "error",

apps/oxlint/fixtures/tsgolint/strict-boolean-expressions/index.ts

@@ -0,0 +1,67 @@
+// Examples of incorrect code for strict-boolean-expressions rule
+
+// Non-boolean values in conditions
+const str = 'hello';
+if (str) { // string is not a boolean
+  console.log('string');
+}
+
+const num = 42;
+if (num) { // number is not a boolean
+  console.log('number');
+}
+
+const obj = { foo: 'bar' };
+if (obj) { // object is not a boolean
+  console.log('object');
+}
+
+// Nullable booleans
+declare const maybeBool: boolean | null;
+if (maybeBool) { // nullable boolean
+  console.log('maybe');
+}
+
+// Undefined checks
+declare const maybeString: string | undefined;
+if (maybeString) { // should explicitly check !== undefined
+  console.log(maybeString);
+}
+
+// Logical operators with non-booleans
+const result1 = str && num;
+const result2 = obj || num;
+
+// While loops with non-boolean
+while (num) {
+  console.log('loop');
+  break;
+}
+
+// Do-while with non-boolean
+do {
+  console.log('do');
+} while (str);
+
+// For loop with non-boolean
+for (let i = 0; i; i++) {
+  console.log('for');
+}
+
+// Ternary with non-boolean
+const ternary = str ? 'yes' : 'no';
+
+// Logical NOT on non-boolean
+const negated = !str;
+
+// Mixed types in logical expressions
+declare const mixed: string | number;
+if (mixed) {
+  console.log('mixed');
+}
+
+// any type (should allow or warn depending on config)
+declare const anyValue: any;
+if (anyValue) {
+  console.log('any');
+}