[WIP] Port TypeScript PR #60304: More rigorous ASI prevention when emitting return/yield

internal/printer/printer.go

@@ -2950,7 +2950,54 @@ func (p *Printer) emitPartiallyEmittedExpression(node *ast.PartiallyEmittedExpre
 }
 
 func (p *Printer) willEmitLeadingNewLine(node *ast.Expression) bool {
-	return false // !!! check if node will emit a leading comment that contains a trailing newline
+	// !!! check if node will emit a leading comment that contains a trailing newline
+	// This is a simplified implementation for the ASI fix.
+	// We assume that PartiallyEmittedExpressions that came from parenthesized 
+	// expressions might have leading comments that need parentheses for ASI prevention.
+	if node.Kind == ast.KindPartiallyEmittedExpression {
+		parseNode := p.emitContext.ParseNode(node.AsNode())
+		if parseNode != nil && parseNode.Kind == ast.KindParenthesizedExpression {
+			// Be more permissive - assume parenthesized expressions in this context
+			// likely had comments that require ASI prevention
+			return true
+		}
+	}
+	return false
+}
+
+func (p *Printer) shouldParenthesizeForNoAsi(node *ast.Expression) bool {
+	if p.commentsDisabled {
+		return false
+	}
+
+	switch node.Kind {
+	case ast.KindPartiallyEmittedExpression:
+		if p.willEmitLeadingNewLine(node) {
+			return true
+		}
+		return p.shouldParenthesizeForNoAsi(node.AsPartiallyEmittedExpression().Expression)
+	case ast.KindPropertyAccessExpression:
+		return p.shouldParenthesizeForNoAsi(node.AsPropertyAccessExpression().Expression)
+	case ast.KindElementAccessExpression:
+		return p.shouldParenthesizeForNoAsi(node.AsElementAccessExpression().Expression)
+	case ast.KindCallExpression:
+		return p.shouldParenthesizeForNoAsi(node.AsCallExpression().Expression)
+	case ast.KindTaggedTemplateExpression:
+		return p.shouldParenthesizeForNoAsi(node.AsTaggedTemplateExpression().Tag)
+	case ast.KindPostfixUnaryExpression:
+		return p.shouldParenthesizeForNoAsi(node.AsPostfixUnaryExpression().Operand)
+	case ast.KindBinaryExpression:
+		return p.shouldParenthesizeForNoAsi(node.AsBinaryExpression().Left)
+	case ast.KindConditionalExpression:
+		return p.shouldParenthesizeForNoAsi(node.AsConditionalExpression().Condition)
+	case ast.KindAsExpression:
+		return p.shouldParenthesizeForNoAsi(node.AsAsExpression().Expression)
+	case ast.KindSatisfiesExpression:
+		return p.shouldParenthesizeForNoAsi(node.AsSatisfiesExpression().Expression)
+	case ast.KindNonNullExpression:
+		return p.shouldParenthesizeForNoAsi(node.AsNonNullExpression().Expression)
+	}
+	return false
 }
 
 func (p *Printer) emitExpressionNoASI(node *ast.Expression, precedence ast.OperatorPrecedence) {
@@ -2966,7 +3013,7 @@ func (p *Printer) emitExpressionNoASI(node *ast.Expression, precedence ast.Opera
 	//	    a;
 	//	}
 	// Due to ASI, this would result in a `return` with no value followed by an unreachable expression statement.
-	if !p.commentsDisabled && node.Kind == ast.KindPartiallyEmittedExpression && p.willEmitLeadingNewLine(node) {
+	if p.shouldParenthesizeForNoAsi(node) {
 		// !!! if there is an original parse tree node, restore it with location to preserve comments and source maps.
 		p.emitExpression(node, ast.OperatorPrecedenceParentheses)
 	} else {

testdata/baselines/reference/submodule/conformance/returnStatementNoAsiAfterTransform(target=es5).js

@@ -67,52 +67,52 @@ function t10() {
 
 //// [returnStatementNoAsiAfterTransform.js]
 function t1() {
-    return 
+    return (
     // comment
-    a;
+    (a));
 }
 function t2() {
-    return 
+    return (
     // comment
-    a + 1;
+    a + 1);
 }
 function t3() {
-    return 
+    return (
     // comment
-    a ? 0 : 1;
+    a ? 0 : 1);
 }
 function t4() {
-    return 
+    return (
     // comment
-    a.b;
+    a.b);
 }
 function t5() {
-    return 
+    return (
     // comment
-    a[a];
+    a[a]);
 }
 function t6() {
-    return 
+    return (
     // comment
-    a();
+    a());
 }
 function t7() {
-    return 
+    return (
     // comment
-    a ``;
+    a ``);
 }
 function t8() {
-    return 
+    return (
     // comment
-    a;
+    (a));
 }
 function t9() {
-    return 
+    return (
     // comment
-    a;
+    (a));
 }
 function t10() {
-    return 
+    return (
     // comment
-    a;
+    (a));
 }

testdata/baselines/reference/submodule/conformance/returnStatementNoAsiAfterTransform(target=es5).js.diff

@@ -9,72 +9,62 @@
 -    return cooked;
 -};
  function t1() {
--    return (
-+    return 
+     return (
      // comment
 -    a);
-+    a;
++    (a));
  }
  function t2() {
--    return (
-+    return 
+     return (
      // comment
 -    a) + 1;
-+    a + 1;
++    a + 1);
  }
  function t3() {
--    return (
-+    return 
+     return (
      // comment
 -    a) ? 0 : 1;
-+    a ? 0 : 1;
++    a ? 0 : 1);
  }
  function t4() {
--    return (
-+    return 
+     return (
      // comment
 -    a).b;
-+    a.b;
++    a.b);
  }
  function t5() {
--    return (
-+    return 
+     return (
      // comment
 -    a)[a];
-+    a[a];
++    a[a]);
  }
  function t6() {
--    return (
-+    return 
+     return (
      // comment
 -    a)();
-+    a();
++    a());
  }
  function t7() {
--    return (
-+    return 
+     return (
      // comment
 -    a)(__makeTemplateObject([""], [""]));
-+    a ``;
++    a ``);
  }
  function t8() {
--    return (
-+    return 
+     return (
      // comment
 -    a);
-+    a;
++    (a));
  }
  function t9() {
--    return (
-+    return 
+     return (
      // comment
 -    a);
-+    a;
++    (a));
  }
  function t10() {
--    return (
-+    return 
+     return (
      // comment
 -    a);
-+    a;
++    (a));
  }

testdata/baselines/reference/submodule/conformance/returnStatementNoAsiAfterTransform(target=esnext).js

@@ -67,52 +67,52 @@ function t10() {
 
 //// [returnStatementNoAsiAfterTransform.js]
 function t1() {
-    return 
+    return (
     // comment
-    a;
+    (a));
 }
 function t2() {
-    return 
+    return (
     // comment
-    a + 1;
+    a + 1);
 }
 function t3() {
-    return 
+    return (
     // comment
-    a ? 0 : 1;
+    a ? 0 : 1);
 }
 function t4() {
-    return 
+    return (
     // comment
-    a.b;
+    a.b);
 }
 function t5() {
-    return 
+    return (
     // comment
-    a[a];
+    a[a]);
 }
 function t6() {
-    return 
+    return (
     // comment
-    a();
+    a());
 }
 function t7() {
-    return 
+    return (
     // comment
-    a ``;
+    a ``);
 }
 function t8() {
-    return 
+    return (
     // comment
-    a;
+    (a));
 }
 function t9() {
-    return 
+    return (
     // comment
-    a;
+    (a));
 }
 function t10() {
-    return 
+    return (
     // comment
-    a;
+    (a));
 }