no-unsafe-any: allow truthyness and falsyness checks

[bugfix] `no-unsafe-any`: allow truthyness and falsyness checks
Fixes: #2981

src/rules/noUnsafeAnyRule.ts

@@ -60,6 +60,7 @@ function walk(ctx: Lint.WalkContext<void>, checker: ts.TypeChecker): void {
 
             case ts.SyntaxKind.Parameter: {
                 const { type, initializer } = node as ts.ParameterDeclaration;
+                // TODO handle destructuring
                 if (initializer !== undefined) {
                     return cb(initializer, /*anyOk*/ type !== undefined && type.kind === ts.SyntaxKind.AnyKeyword);
                 }
@@ -187,6 +188,29 @@ function walk(ctx: Lint.WalkContext<void>, checker: ts.TypeChecker): void {
                 return;
             }
 
+            case ts.SyntaxKind.IfStatement: {
+                const { expression, thenStatement, elseStatement } = node as ts.IfStatement;
+                cb(expression, true); // allow truthyness check
+                cb(thenStatement);
+                if (elseStatement !== undefined) { cb(elseStatement); }
+                return;
+            }
+
+            case ts.SyntaxKind.PrefixUnaryExpression: {
+                const {operator, operand} = node as ts.PrefixUnaryExpression;
+                cb(operand, operator === ts.SyntaxKind.ExclamationToken); // allow falsyness check
+                check();
+                return;
+            }
+
+            case ts.SyntaxKind.ForStatement: {
+                const { initializer, condition, incrementor, statement } = node as ts.ForStatement;
+                if (initializer !== undefined) { cb(initializer); }
+                if (condition !== undefined) { cb(condition, true); } // allow truthyness check
+                if (incrementor !== undefined) { cb(incrementor); }
+                return cb(statement);
+            }
+
             default:
                 if (!(isExpression(node) && check())) {
                     return ts.forEachChild(node, cb);
@@ -230,6 +254,8 @@ function walk(ctx: Lint.WalkContext<void>, checker: ts.TypeChecker): void {
                 return cb(right);
 
             case ts.SyntaxKind.CommaToken: // Allow `any, any`
+            case ts.SyntaxKind.BarBarToken: // Allow `any || any`
+            case ts.SyntaxKind.AmpersandAmpersandToken: // Allow `any && any`
                 cb(left, /*anyOk*/ true);
                 return cb(right, /*anyOk*/ true);
 

test/rules/no-unsafe-any/test.ts.lint

@@ -181,4 +181,9 @@ switch (x.y) {
 
 declare global {}
 
+if (x) {}
+if (!x) {}
+if (!x || x) {}
+for (;x;) {}
+
 [0]: Unsafe use of expression of type 'any'.