Fix preserveNewlines printer option when a list child has the same start or end as its parent

Author: andrewbranch

src/compiler/emitter.ts

@@ -4301,6 +4301,7 @@ namespace ts {
                         return getEffectiveLines(
                             includeComments => getLinesBetweenPositionAndPrecedingNonWhitespaceCharacter(
                                 firstChild.pos,
+                                parentNode.pos,
                                 currentSourceFile!,
                                 includeComments));
                     }
@@ -4358,6 +4359,7 @@ namespace ts {
                         return getEffectiveLines(
                             includeComments => getLinesBetweenPositionAndNextNonWhitespaceCharacter(
                                 lastChild.end,
+                                parentNode.end,
                                 currentSourceFile!,
                                 includeComments));
                     }

src/compiler/utilities.ts

@@ -4776,19 +4776,19 @@ namespace ts {
         return positionIsSynthesized(range.pos) ? -1 : skipTrivia(sourceFile.text, range.pos, /*stopAfterLineBreak*/ false, includeComments);
     }
 
-    export function getLinesBetweenPositionAndPrecedingNonWhitespaceCharacter(pos: number, sourceFile: SourceFile, includeComments?: boolean) {
+    export function getLinesBetweenPositionAndPrecedingNonWhitespaceCharacter(pos: number, stopPos: number, sourceFile: SourceFile, includeComments?: boolean) {
         const startPos = skipTrivia(sourceFile.text, pos, /*stopAfterLineBreak*/ false, includeComments);
-        const prevPos = getPreviousNonWhitespacePosition(startPos, sourceFile);
+        const prevPos = getPreviousNonWhitespacePosition(startPos, stopPos, sourceFile);
         return getLinesBetweenPositions(sourceFile, prevPos || 0, startPos);
     }
 
-    export function getLinesBetweenPositionAndNextNonWhitespaceCharacter(pos: number, sourceFile: SourceFile, includeComments?: boolean) {
+    export function getLinesBetweenPositionAndNextNonWhitespaceCharacter(pos: number, stopPos: number, sourceFile: SourceFile, includeComments?: boolean) {
         const nextPos = skipTrivia(sourceFile.text, pos, /*stopAfterLineBreak*/ false, includeComments);
-        return getLinesBetweenPositions(sourceFile, pos, nextPos);
+        return getLinesBetweenPositions(sourceFile, pos, Math.min(stopPos, nextPos));
     }
 
-    function getPreviousNonWhitespacePosition(pos: number, sourceFile: SourceFile) {
-        while (pos-- > 0) {
+    function getPreviousNonWhitespacePosition(pos: number, stopPos = 0, sourceFile: SourceFile) {
+        while (pos-- > stopPos) {
             if (!isWhiteSpaceLike(sourceFile.text.charCodeAt(pos))) {
                 return pos;
             }

tests/cases/fourslash/textChangesPreserveNewlines8.ts

@@ -0,0 +1,29 @@
+// #37813
+
+/// <reference path="fourslash.ts" />
+
+////function foo() {
+////    /*1*/var x: number
+////
+////    x = 10;
+////    return x;/*2*/
+////}
+
+goTo.select("1", "2");
+edit.applyRefactor({
+  refactorName: "Extract Symbol",
+  actionName: "function_scope_1",
+  actionDescription: "Extract to function in global scope",
+  newContent:
+`function foo() {
+    return /*RENAME*/newFunction();
+}
+
+function newFunction() {
+    var x: number;
+
+    x = 10;
+    return x;
+}
+`
+});