Harden Extract Symbol against symbols without declarations

src/harness/unittests/extractFunctions.ts

@@ -552,6 +552,11 @@ export default class {
     M() {
         [#|1 + 1|];
     }
+}`);
+
+    testExtractFunction("extractFunction_NoDeclarations", `
+function F() {
+[#|arguments.length|]; // arguments has no declaration
 }`);
     });
 

src/services/refactors/extractSymbol.ts

@@ -1689,7 +1689,8 @@ namespace ts.refactor.extractSymbol {
                 return symbolId;
             }
             // find first declaration in this file
-            const declInFile = find(symbol.getDeclarations(), d => d.getSourceFile() === sourceFile);
+            const decls = symbol.getDeclarations();
+            const declInFile = decls && find(decls, d => d.getSourceFile() === sourceFile);
             if (!declInFile) {
                 return undefined;
             }
@@ -1782,7 +1783,8 @@ namespace ts.refactor.extractSymbol {
             if (!symbol) {
                 return undefined;
             }
-            if (symbol.getDeclarations().some(d => d.parent === scopeDecl)) {
+            const decls = symbol.getDeclarations();
+            if (decls && decls.some(d => d.parent === scopeDecl)) {
                 return createIdentifier(symbol.name);
             }
             const prefix = tryReplaceWithQualifiedNameOrPropertyAccess(symbol.parent, scopeDecl, isTypeNode);

tests/baselines/reference/extractFunction/extractFunction_NoDeclarations.js

@@ -0,0 +1,24 @@
+// ==ORIGINAL==
+
+function F() {
+/*[#|*/arguments.length/*|]*/; // arguments has no declaration
+}
+// ==SCOPE::Extract to inner function in function 'F'==
+
+function F() {
+    /*RENAME*/newFunction(); // arguments has no declaration
+
+
+    function newFunction() {
+        arguments.length;
+    }
+}
+// ==SCOPE::Extract to function in global scope==
+
+function F() {
+    /*RENAME*/newFunction(); // arguments has no declaration
+}
+
+function newFunction() {
+    arguments.length;
+}

tests/baselines/reference/extractFunction/extractFunction_NoDeclarations.ts

@@ -0,0 +1,24 @@
+// ==ORIGINAL==
+
+function F() {
+/*[#|*/arguments.length/*|]*/; // arguments has no declaration
+}
+// ==SCOPE::Extract to inner function in function 'F'==
+
+function F() {
+    /*RENAME*/newFunction(); // arguments has no declaration
+
+
+    function newFunction() {
+        arguments.length;
+    }
+}
+// ==SCOPE::Extract to function in global scope==
+
+function F() {
+    /*RENAME*/newFunction(); // arguments has no declaration
+}
+
+function newFunction() {
+    arguments.length;
+}