Stop inadvertently exempting expression statements from check

Author: amcasey

src/harness/unittests/extractConstants.ts

@@ -40,6 +40,13 @@ function F() {
 }
         `);
 
+        testExtractConstant("extractConstant_ExpressionStatementConsumesLocal", `
+function F() {
+    let i = 0;
+    [#|i++|];
+}
+        `);
+
         testExtractConstant("extractConstant_BlockScopes_NoDependencies",
             `for (let i = 0; i < 10; i++) {
     for (let j = 0; j < 10; j++) {

src/services/refactors/extractSymbol.ts

@@ -1351,14 +1351,13 @@ namespace ts.refactor.extractSymbol {
         }
 
         for (let i = 0; i < scopes.length; i++) {
-            if (!isReadonlyArray(targetRange.range)) {
-                const scopeUsages = usagesPerScope[i];
-                // Special case: in the innermost scope, all usages are available.
-                // (The computed value reflects the value at the top-level of the scope, but the
-                // local will actually be declared at the same level as the extracted expression).
-                if (i > 0 && (scopeUsages.usages.size > 0 || scopeUsages.typeParameterUsages.size > 0)) {
-                    constantErrorsPerScope[i].push(createDiagnosticForNode(targetRange.range, Messages.CannotAccessVariablesFromNestedScopes));
-                }
+            const scopeUsages = usagesPerScope[i];
+            // Special case: in the innermost scope, all usages are available.
+            // (The computed value reflects the value at the top-level of the scope, but the
+            // local will actually be declared at the same level as the extracted expression).
+            if (i > 0 && (scopeUsages.usages.size > 0 || scopeUsages.typeParameterUsages.size > 0)) {
+                const errorNode = isReadonlyArray(targetRange.range) ? targetRange.range[0] : targetRange.range;
+                constantErrorsPerScope[i].push(createDiagnosticForNode(errorNode, Messages.CannotAccessVariablesFromNestedScopes));
             }
 
             let hasWrite = false;

tests/baselines/reference/extractConstant/extractConstant_ExpressionStatementConsumesLocal.js

@@ -0,0 +1,14 @@
+// ==ORIGINAL==
+
+function F() {
+    let i = 0;
+    i++;
+}
+        
+// ==SCOPE::Extract to constant in enclosing scope==
+
+function F() {
+    let i = 0;
+    const /*RENAME*/newLocal = i++;
+}
+        

tests/baselines/reference/extractConstant/extractConstant_ExpressionStatementConsumesLocal.ts

@@ -0,0 +1,14 @@
+// ==ORIGINAL==
+
+function F() {
+    let i = 0;
+    i++;
+}
+        
+// ==SCOPE::Extract to constant in enclosing scope==
+
+function F() {
+    let i = 0;
+    const /*RENAME*/newLocal = i++;
+}
+