Generic parser fixes (#1959)

This fixes some issues with the handling of separators in GenericParser

pkl-parser/src/main/java/org/pkl/parser/GenericParserImpl.java

@@ -755,37 +755,43 @@ class GenericParserImpl {
 
   private void parseAccess(List<Node> children) {
     children.add(parseIdentifier());
-    var typeArgs = tryParseTypeArgumentList();
+    var typeArgs = tryParseTypeArgumentList(children);
     if (typeArgs != null) {
       // `tryParseTypeArgumentList` guarantees that an argument list follows
       children.add(typeArgs);
       ff(children);
       children.add(parseArgumentList());
-    } else if (lookahead() == Token.LPAREN
-        && noSemicolonInbetween()
-        && _lookahead.newLinesBetween == 0) {
-      ff(children);
-      children.add(parseArgumentList());
+    } else {
+      var fullLookahead = fullLookahead();
+      if (fullLookahead.tk.token == Token.LPAREN
+          && !fullLookahead.hasSemicolon
+          && fullLookahead.tk.newLinesBetween == 0) {
+        ff(children);
+        children.add(parseArgumentList());
+      }
     }
   }
 
-  private @Nullable Node tryParseTypeArgumentList() {
-    if (lookahead() != Token.LT
-        || !noSemicolonInbetween()
-        || _lookahead.newLinesBetween != 0
-        || failedTypeArgAttempts.contains(spanLookahead.charIndex())
-        || !isTypeArgCandidate(spanLookahead.charIndex())) {
+  private @Nullable Node tryParseTypeArgumentList(List<Node> children) {
+    var fullLookahead = fullLookahead();
+    if (fullLookahead.tk.token != Token.LT
+        || fullLookahead.hasSemicolon
+        || fullLookahead.tk.newLinesBetween != 0
+        || failedTypeArgAttempts.contains(fullLookahead.tk.span.charIndex())
+        || !isTypeArgCandidate(fullLookahead.tk.span.charIndex())) {
       return null;
     }
     var savedCursor = cursor;
-    var savedCharIndex = spanLookahead.charIndex();
+    var savedCharIndex = fullLookahead.tk.span.charIndex();
     var savedIsSpeculativeParse = isSpeculativeParse;
     isSpeculativeParse = true;
     try {
+      var affixes = new ArrayList<Node>();
+      ff(affixes);
       var typeArgs = parseTypeArgumentList();
-      if (lookahead() == Token.LPAREN
-          && noSemicolonInbetween()
-          && _lookahead.newLinesBetween == 0) {
+      var fla = fullLookahead();
+      if (fla.tk.token == Token.LPAREN && !fla.hasSemicolon && fla.tk.newLinesBetween == 0) {
+        children.addAll(affixes);
         return typeArgs;
       }
     } catch (GenericParserError ignored) {
@@ -1310,7 +1316,7 @@ class GenericParserImpl {
       }
       // constrained types: have to start in the same line as the type
       var fla = fullLookahead();
-      if (fla.tk.token == Token.LPAREN && noSemicolonInbetween() && fla.tk.newLinesBetween == 0) {
+      if (fla.tk.token == Token.LPAREN && !fla.hasSemicolon && fla.tk.newLinesBetween == 0) {
         ff(children);
         var constraint = new ArrayList<Node>();
         constraint.add(makeTerminal(next()));
@@ -1565,10 +1571,6 @@ class GenericParserImpl {
     return tmp;
   }
 
-  private boolean noSemicolonInbetween() {
-    return tokens.get(cursor - 1).token != Token.SEMICOLON;
-  }
-
   private void backtrackTo(int point) {
     cursor = point;
     var tmp = tokens.get(cursor);

pkl-parser/src/test/kotlin/org/pkl/parser/GenericParserTest.kt

@@ -45,4 +45,104 @@ class GenericParserTest {
     // 1 second should still catch if we see exponential regressions
     assertTimeoutPreemptively(Duration.ofSeconds(1)) { GenericParser().parseModule(code) }
   }
+
+  // TODO: move these into ParserSnippetTests
+  @Test
+  fun `parse separator correctly -- semicolon`() {
+    val code =
+      """
+      result = new Listing {
+        a;
+        (b) { c = 1 }
+      }
+      """
+        .trimIndent()
+    assertThat(renderGenericCode(code))
+      .isEqualTo(
+        """
+        (module
+          (classProperty
+            (identifier)
+            (newExpr
+              (declaredType
+                (qualifiedIdentifier
+                  (identifier)))
+              (objectBody
+                (objectElement
+                  (unqualifiedAccessExpr
+                    (identifier)))
+                (objectElement
+                  (amendsExpr
+                    (parenthesizedExpr
+                      (unqualifiedAccessExpr
+                        (identifier)))
+                    (objectBody
+                      (objectProperty
+                        (identifier)
+                        (intLiteralExpr)))))))))
+        """
+          .trimIndent()
+      )
+  }
+
+  @Test
+  fun `parse separator correctly -- line comment in between`() {
+    val code =
+      """
+      result = new Listing {
+        a // some comment
+        (b) { c = 1 }
+      }
+      """
+        .trimIndent()
+    assertThat(renderGenericCode(code))
+      .isEqualTo(
+        """
+        (module
+          (classProperty
+            (identifier)
+            (newExpr
+              (declaredType
+                (qualifiedIdentifier
+                  (identifier)))
+              (objectBody
+                (objectElement
+                  (unqualifiedAccessExpr
+                    (identifier)))
+                (objectElement
+                  (amendsExpr
+                    (parenthesizedExpr
+                      (unqualifiedAccessExpr
+                        (identifier)))
+                    (objectBody
+                      (objectProperty
+                        (identifier)
+                        (intLiteralExpr)))))))))
+        """
+          .trimIndent()
+      )
+  }
+
+  @Test
+  fun `parse type arg list -- comment in between`() {
+    val code = "foo = a /* some comment */ <b>(c)"
+    assertThat(renderGenericCode(code))
+      .isEqualTo(
+        """
+        (module
+          (classProperty
+            (identifier)
+            (unqualifiedAccessExpr
+              (identifier)
+              (typeArgumentList
+                (declaredType
+                  (qualifiedIdentifier
+                    (identifier))))
+              (argumentList
+                (unqualifiedAccessExpr
+                  (identifier))))))
+        """
+          .trimIndent()
+      )
+  }
 }

pkl-parser/src/test/kotlin/org/pkl/parser/ParserComparisonTest.kt

@@ -64,13 +64,6 @@ class ParserComparisonTest {
       return renderer.render(mod)
     }
 
-    private fun renderGenericCode(code: String): String {
-      val parser = GenericParser()
-      val mod = parser.parseModule(code)
-      val renderer = GenericSexpRenderer(code)
-      return renderer.render(mod)
-    }
-
     // tests that are not syntactically valid Pkl
     private val exceptions =
       setOf(

pkl-parser/src/test/kotlin/org/pkl/parser/TestUtils.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright © 2026 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.parser
+
+fun renderGenericCode(code: String): String {
+  val parser = GenericParser()
+  val mod = parser.parseModule(code)
+  val renderer = GenericSexpRenderer(code)
+  return renderer.render(mod)
+}