Improve printing of [no LineTerminator here] with comments

packages/babel-generator/src/generators/expressions.ts

@@ -26,14 +26,11 @@ export function UnaryExpression(this: Printer, node: t.UnaryExpression) {
 }
 
 export function DoExpression(this: Printer, node: t.DoExpression) {
-  // ensure no line terminator between `async` and `do`
-  this.ensureNoLineTerminator(() => {
-    if (node.async) {
-      this.word("async");
-      this.space();
-    }
-    this.word("do");
-  });
+  if (node.async) {
+    this.word("async", true);
+    this.space();
+  }
+  this.word("do");
   this.space();
   this.print(node.body, node);
 }
@@ -230,12 +227,10 @@ export function AwaitExpression(this: Printer, node: t.AwaitExpression) {
 }
 
 export function YieldExpression(this: Printer, node: t.YieldExpression) {
-  this.word("yield");
+  this.word("yield", node.delegate);
 
   if (node.delegate) {
-    this.ensureNoLineTerminator(() => {
-      this.token("*");
-    });
+    this.token("*");
     if (node.argument) {
       this.space();
       // line terminators are allowed after yield*
@@ -360,12 +355,9 @@ export function V8IntrinsicIdentifier(
 }
 
 export function ModuleExpression(this: Printer, node: t.ModuleExpression) {
-  this.word("module");
+  this.word("module", true);
   this.space();
-  // ensure no line terminator between `module` and `{`
-  this.ensureNoLineTerminator(() => {
-    this.token("{");
-  });
+  this.token("{");
   this.indent();
   const { body } = node;
   if (body.body.length || body.directives.length) {

packages/babel-generator/src/generators/methods.ts

@@ -10,6 +10,7 @@ export function _params(
   this.token("(");
   this._parameters(node.params, node);
   this.token(")");
+  this._noLineTerminator = true;
 
   this.print(node.returnType, node, node.type === "ArrowFunctionExpression");
 }
@@ -72,11 +73,8 @@ export function _methodHead(this: Printer, node: t.Method | t.TSDeclareMethod) {
     this.space();
   }
 
-  const { _noLineTerminator } = this;
   if (node.async) {
-    // ensure no line terminator between async and class element name / *
-    this._noLineTerminator = true;
-    this.word("async");
+    this.word("async", true);
     this.space();
   }
 
@@ -87,18 +85,15 @@ export function _methodHead(this: Printer, node: t.Method | t.TSDeclareMethod) {
   ) {
     if (node.generator) {
       this.token("*");
-      this._noLineTerminator = _noLineTerminator;
     }
   }
 
   if (node.computed) {
     this.token("[");
-    this._noLineTerminator = _noLineTerminator;
     this.print(key, node);
     this.token("]");
   } else {
     this.print(key, node);
-    this._noLineTerminator = _noLineTerminator;
   }
 
   if (
@@ -118,13 +113,14 @@ export function _predicate(
     | t.FunctionDeclaration
     | t.FunctionExpression
     | t.ArrowFunctionExpression,
+  noLineTerminatorAfter?: boolean,
 ) {
   if (node.predicate) {
     if (!node.returnType) {
       this.token(":");
     }
     this.space();
-    this.print(node.predicate, node);
+    this.print(node.predicate, node, noLineTerminatorAfter);
   }
 }
 
@@ -172,10 +168,8 @@ export function ArrowFunctionExpression(
   this: Printer,
   node: t.ArrowFunctionExpression,
 ) {
-  const { _noLineTerminator } = this;
   if (node.async) {
-    this._noLineTerminator = true;
-    this.word("async");
+    this.word("async", true);
     this.space();
   }
 
@@ -188,22 +182,18 @@ export function ArrowFunctionExpression(
     isIdentifier((firstParam = node.params[0])) &&
     !hasTypesOrComments(node, firstParam)
   ) {
-    this.print(firstParam, node);
-    this._noLineTerminator = _noLineTerminator;
+    this.print(firstParam, node, true);
   } else {
-    this._noLineTerminator = _noLineTerminator;
     this._params(node);
   }
 
-  this._predicate(node);
-  this.ensureNoLineTerminator(() => {
-    this.space();
-    // When printing (x)/*1*/=>{}, we remove the parentheses
-    // and thus there aren't two contiguous inner tokens.
-    // We forcefully print inner comments here.
-    this.printInnerComments();
-    this.token("=>");
-  });
+  this._predicate(node, true);
+  this.space();
+  // When printing (x)/*1*/=>{}, we remove the parentheses
+  // and thus there aren't two contiguous inner tokens.
+  // We forcefully print inner comments here.
+  this.printInnerComments();
+  this.token("=>");
 
   this.space();
 

packages/babel-generator/src/generators/modules.ts

@@ -70,6 +70,7 @@ export function _printAssertions(
   this: Printer,
   node: Extract<t.Node, { assertions?: t.ImportAttribute[] }>,
 ) {
+  this.word("assert");
   this.space();
   this.token("{");
   this.space();
@@ -94,11 +95,8 @@ export function ExportAllDeclaration(
   this.space();
   // @ts-expect-error Fixme: assertions is not defined in DeclareExportAllDeclaration
   if (node.assertions?.length) {
-    this.ensureNoLineTerminator(() => {
-      this.print(node.source, node);
-      this.space();
-      this.word("assert");
-    });
+    this.print(node.source, node, true);
+    this.space();
     // @ts-expect-error Fixme: assertions is not defined in DeclareExportAllDeclaration
     this._printAssertions(node);
   } else {
@@ -169,11 +167,8 @@ export function ExportNamedDeclaration(
       this.word("from");
       this.space();
       if (node.assertions?.length) {
-        this.ensureNoLineTerminator(() => {
-          this.print(node.source, node);
-          this.space();
-          this.word("assert");
-        });
+        this.print(node.source, node, true);
+        this.space();
         this._printAssertions(node);
       } else {
         this.print(node.source, node);
@@ -258,10 +253,7 @@ export function ImportDeclaration(this: Printer, node: t.ImportDeclaration) {
 
   if (node.assertions?.length) {
     this.print(node.source, node, true);
-    this.ensureNoLineTerminator(() => {
-      this.space();
-      this.word("assert");
-    });
+    this.space();
     this._printAssertions(node);
   } else {
     this.print(node.source, node);

packages/babel-generator/src/generators/statements.ts

@@ -1,5 +1,4 @@
 import type Printer from "../printer";
-import type { PrintJoinOptions } from "../printer";
 import {
   isFor,
   isForStatement,
@@ -262,12 +261,7 @@ export function VariableDeclaration(
   }
 
   const { kind } = node;
-  this.word(kind);
-  const { _noLineTerminator } = this;
-  if (kind === "using") {
-    // ensure no line break after `using`
-    this._noLineTerminator = true;
-  }
+  this.word(kind, kind === "using");
   this.space();
 
   let hasInits = false;
@@ -293,24 +287,13 @@ export function VariableDeclaration(
   //       bar = "foo";
   //
 
-  let iterator: PrintJoinOptions["iterator"] | undefined;
-  if (kind === "using") {
-    // Ensure no line break between `using` and the first declarator
-    iterator = (_, i: number) => {
-      if (i === 0) {
-        this._noLineTerminator = _noLineTerminator;
-      }
-    };
-  }
-
   this.printList(node.declarations, node, {
     separator: hasInits
       ? function (this: Printer) {
           this.token(",");
           this.newline();
         }
       : undefined,
-    iterator,
     indent: node.declarations.length > 1 ? true : false,
   });