fix: Removing last modifier should not remove preceding comments.

lib/ts-simple-ast.d.ts

@@ -4271,7 +4271,7 @@ export declare class Node<NodeType extends ts.Node = ts.Node> {
      */
     getFullStart(): number;
     /**
-     * Gets the first source file text position from the result of .getPos() that is not whitespace.
+     * Gets the first source file text position that is not whitespace.
      */
     getNonWhitespaceStart(): number;
     /**

src/compiler/ast/common/Node.ts

@@ -780,10 +780,15 @@ export class Node<NodeType extends ts.Node = ts.Node> {
     }
 
     /**
-     * Gets the first source file text position from the result of .getPos() that is not whitespace.
+     * Gets the first source file text position that is not whitespace.
      */
-    getNonWhitespaceStart() {
-        return getNextNonWhitespacePos(this.sourceFile.getFullText(), this.getPos());
+    getNonWhitespaceStart(): number {
+        const parent = this.getParent() as Node | undefined;
+        const parentTakesPrecedence = parent != null
+            && !TypeGuards.isSourceFile(parent)
+            && parent.getPos() === this.getPos();
+
+        return getNextNonWhitespacePos(this.sourceFile.getFullText(), parentTakesPrecedence ? this.getStart(true) : this.getPos());
     }
 
     /**

src/tests/compiler/base/modifierableNodeTests.ts

@@ -135,5 +135,17 @@ describe(nameof(ModifierableNode), () => {
             firstChild.toggleModifier("export", false);
             expect(firstChild.getText()).to.equal("class Identifier {}");
         });
+
+        it("should not remove jsdoc comment", () => {
+            const { sourceFile, firstChild } = getInfoFromText<ClassDeclaration>("/** test */declare function Test {}");
+            firstChild.toggleModifier("declare", false);
+            expect(sourceFile.getFullText()).to.equal("/** test */function Test {}");
+        });
+
+        it("should not remove comment", () => {
+            const { sourceFile, firstChild } = getInfoFromText<ClassDeclaration>("// test\ndeclare function Test {}");
+            firstChild.toggleModifier("declare", false);
+            expect(sourceFile.getFullText()).to.equal("// test\nfunction Test {}");
+        });
     });
 });

src/tests/compiler/common/nodeTests.ts

@@ -1498,4 +1498,30 @@ class MyClass {
             expect(syntaxList.getTrailingTriviaEnd()).to.equal(expectedTriviaEnd);
         });
     });
+
+    describe(nameof<Node>(n => n.getNonWhitespaceStart), () => {
+        function doTest(text: string, selectNode: (sourceFile: SourceFile) => Node, expected: number) {
+            const { sourceFile } = getInfoFromText(text);
+            const node = selectNode(sourceFile);
+            expect(node.getNonWhitespaceStart()).to.equal(expected);
+        }
+
+        // todo: more tests
+
+        it("should include the jsdocs if a node with jsdocs", () => {
+            doTest("/** test */declare function test() {}", sourceFile => sourceFile.getFunctions()[0], 0);
+        });
+
+        it("should not include jsdocs when the pos is before and the start is after", () => {
+            doTest("/** test */declare function test() {}", sourceFile => sourceFile.getFunctions()[0].getModifiers()[0], 11);
+        });
+
+        it("should not include the comment when for a child with the same pos as the parent", () => {
+            doTest("// testing\ndeclare function test() {}", sourceFile => sourceFile.getFunctions()[0].getModifiers()[0], 11);
+        });
+
+        it("should include the comment for the node that handles it", () => {
+            doTest("// testing\ndeclare function test() {}", sourceFile => sourceFile.getFunctions()[0], 0);
+        });
+    });
 });