fix: analysis ParenthesizedExpression or FunctionExpression more correctly in parser (AssemblyScript#2605)

Author: HerrCai0907

Diff for: src/parser.ts

@@ -514,19 +514,23 @@ export class Parser extends DiagnosticEmitter {
       if (signature) {
         if (isInnerParenthesized) {
           if (!tn.skip(Token.CloseParen)) {
-            this.error(
-              DiagnosticCode._0_expected,
-              tn.range(), ")"
-            );
+            if (!suppressErrors) {
+              this.error(
+                DiagnosticCode._0_expected,
+                tn.range(), ")"
+              );
+            }
             return null;
           }
         }
         type = signature;
       } else if (isInnerParenthesized || this.tryParseSignatureIsSignature) {
-        this.error(
-          DiagnosticCode.Unexpected_token,
-          tn.range()
-        );
+        if (!suppressErrors) {
+          this.error(
+            DiagnosticCode.Unexpected_token,
+            tn.range()
+          );
+        }
         return null;
       // Type (',' Type)* ')'
       } else if (acceptParenthesized) {
@@ -545,10 +549,12 @@ export class Parser extends DiagnosticEmitter {
         type.range.start = startPos;
         type.range.end = tn.pos;
       } else {
-        this.error(
-          DiagnosticCode.Unexpected_token,
-          tn.range()
-        );
+        if (!suppressErrors) {
+          this.error(
+            DiagnosticCode.Unexpected_token,
+            tn.range()
+          );
+        }
         return null;
       }
 
@@ -3780,14 +3786,20 @@ export class Parser extends DiagnosticEmitter {
 
                 // if we got here, check for arrow
                 case Token.CloseParen: {
-                  if (
-                    !tn.skip(Token.Colon) &&
-                    !tn.skip(Token.Equals_GreaterThan)
-                  ) {
-                    again = false;
-                    break;
+                    // `Identifier):Type =>` is function expression
+                  if (tn.skip(Token.Colon)) {
+                    let type = this.parseType(tn, true, true);
+                    if (type == null) {
+                      again = false;
+                      break;
+                    }
                   }
-                  // fall-through
+                  if (tn.skip(Token.Equals_GreaterThan)) {
+                    tn.reset(state);
+                    return this.parseFunctionExpression(tn);
+                  }
+                  again = false;
+                  break;
                 }
                 // function expression
                 case Token.Colon: {    // type annotation

Diff for: tests/parser/arrow-functions.ts

@@ -9,4 +9,6 @@ x => x;
 
 // not an array function
 (b ? x : y);
+b ? (x) : y;
+b ? (x):i32=>1 : y;
 (b ? f : g)();

Diff for: tests/parser/arrow-functions.ts.fixture.ts

@@ -6,4 +6,6 @@
 x => x;
 () => {};
 (b ? x : y);
+b ? (x) : y;
+b ? (x): i32 => 1 : y;
 (b ? f : g)();