Improve error position/range for arrow functions with expression body

Fixes #57866
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 1ff3a2a..2ea2c5e 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -2527,6 +2527,14 @@ export function getErrorSpanForNode(sourceFile: SourceFile, node: Node): TextSpa
         }
     }

+    if (node.parent !== undefined && node.parent.kind === SyntaxKind.ArrowFunction) {
+        const arrowFn = node.parent as ArrowFunction;
+        if (arrowFn.body === node && arrowFn.type !== undefined) {
+            const pos = skipTrivia(sourceFile.text, arrowFn.type.pos);
+            return getSpanOfTokenAtPosition(sourceFile, pos);
+        }
+    }
+
     if (errorNode === undefined) {
         // If we don't have a better node, then just set the error on the first token of
         // construct.
diff --git a/tests/baselines/reference/conditionalTypes1.errors.txt b/tests/baselines/reference/conditionalTypes1.errors.txt
index aa2ae24..476345e 100644
--- a/tests/baselines/reference/conditionalTypes1.errors.txt
+++ b/tests/baselines/reference/conditionalTypes1.errors.txt
@@ -73,7 +73,7 @@ conditionalTypes1.ts(160,5): error TS2322: Type 'T' is not assignable to type 'Z
   Type 'string | number' is not assignable to type 'ZeroOf<T>'.
     Type 'string' is not assignable to type 'ZeroOf<T>'.
 conditionalTypes1.ts(263,9): error TS2403: Subsequent variable declarations must have the same type.  Variable 'z' must be of type 'T1', but here has type 'Foo<T & U>'.
-conditionalTypes1.ts(288,43): error TS2322: Type 'T95<U>' is not assignable to type 'T94<U>'.
+conditionalTypes1.ts(288,33): error TS2322: Type 'T95<U>' is not assignable to type 'T94<U>'.
   Type 'number | boolean' is not assignable to type 'T94<U>'.
     Type 'number' is not assignable to type 'T94<U>'.
       Type 'boolean' is not assignable to type 'true'.
@@ -465,7 +465,7 @@ conditionalTypes1.ts(288,43): error TS2322: Type 'T95<U>' is not assignable to t
     type T95<T> = T extends string ? boolean : number;
     const f44 = <U>(value: T94<U>): T95<U> => value;
     const f45 = <U>(value: T95<U>): T94<U> => value;  // Error
-                                              ~~~~~
+                                    ~~~
 !!! error TS2322: Type 'T95<U>' is not assignable to type 'T94<U>'.
 !!! error TS2322:   Type 'number | boolean' is not assignable to type 'T94<U>'.
 !!! error TS2322:     Type 'number' is not assignable to type 'T94<U>'.
diff --git a/tests/baselines/reference/mappedTypeConstraints2.errors.txt b/tests/baselines/reference/mappedTypeConstraints2.errors.txt
index 0d3b324..098bbd3 100644
--- a/tests/baselines/reference/mappedTypeConstraints2.errors.txt
+++ b/tests/baselines/reference/mappedTypeConstraints2.errors.txt
@@ -6,7 +6,7 @@ mappedTypeConstraints2.ts(16,11): error TS2322: Type 'Mapped3<K>[Uppercase<K>]'
 mappedTypeConstraints2.ts(42,7): error TS2322: Type 'Mapped6<K>[keyof Mapped6<K>]' is not assignable to type '`_${string}`'.
   Type 'Mapped6<K>[string] | Mapped6<K>[number] | Mapped6<K>[symbol]' is not assignable to type '`_${string}`'.
     Type 'Mapped6<K>[string]' is not assignable to type '`_${string}`'.
-mappedTypeConstraints2.ts(51,57): error TS2322: Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'.
+mappedTypeConstraints2.ts(51,52): error TS2322: Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'.
   'T' could be instantiated with an arbitrary type which could be unrelated to 'Foo<T>[`get${T}`]'.
 mappedTypeConstraints2.ts(82,9): error TS2322: Type 'ObjectWithUnderscoredKeys<K>[`_${K}`]' is not assignable to type 'true'.
   Type 'ObjectWithUnderscoredKeys<K>[`_${string}`]' is not assignable to type 'true'.
@@ -75,7 +75,7 @@ mappedTypeConstraints2.ts(82,9): error TS2322: Type 'ObjectWithUnderscoredKeys<K
     };

     const get = <T extends string>(t: T, foo: Foo<T>): T => foo[`get${t}`];  // Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'
-                                                            ~~~~~~~~~~~~~~
+                                                       ~
 !!! error TS2322: Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'.
 !!! error TS2322:   'T' could be instantiated with an arbitrary type which could be unrelated to 'Foo<T>[`get${T}`]'.

diff --git a/tests/baselines/reference/parserArrowFunctionExpression17.errors.txt b/tests/baselines/reference/parserArrowFunctionExpression17.errors.txt
index 28091b1..73c2b637f0 100644
--- a/tests/baselines/reference/parserArrowFunctionExpression17.errors.txt
+++ b/tests/baselines/reference/parserArrowFunctionExpression17.errors.txt
@@ -1,12 +1,12 @@
 fileJs.js(1,1): error TS2304: Cannot find name 'a'.
 fileJs.js(1,5): error TS2304: Cannot find name 'b'.
 fileJs.js(1,15): error TS2304: Cannot find name 'd'.
+fileJs.js(1,15): error TS2304: Cannot find name 'e'.
 fileJs.js(1,15): error TS8010: Type annotations can only be used in TypeScript files.
-fileJs.js(1,20): error TS2304: Cannot find name 'e'.
 fileTs.ts(1,1): error TS2304: Cannot find name 'a'.
 fileTs.ts(1,5): error TS2304: Cannot find name 'b'.
 fileTs.ts(1,15): error TS2304: Cannot find name 'd'.
-fileTs.ts(1,20): error TS2304: Cannot find name 'e'.
+fileTs.ts(1,15): error TS2304: Cannot find name 'e'.

 ==== fileJs.js (5 errors) ====
@@ -18,9 +18,9 @@ fileTs.ts(1,20): error TS2304: Cannot find name 'e'.
                   ~
 !!! error TS2304: Cannot find name 'd'.
                   ~
-!!! error TS8010: Type annotations can only be used in TypeScript files.
-                       ~
 !!! error TS2304: Cannot find name 'e'.
+                  ~
+!!! error TS8010: Type annotations can only be used in TypeScript files.

 ==== fileTs.ts (4 errors) ====
     a ? b : (c) : d => e
@@ -30,6 +30,6 @@ fileTs.ts(1,20): error TS2304: Cannot find name 'e'.
 !!! error TS2304: Cannot find name 'b'.
                   ~
 !!! error TS2304: Cannot find name 'd'.
-                       ~
+                  ~
 !!! error TS2304: Cannot find name 'e'.

\ No newline at end of file

Author: OliverJAsh

src/compiler/utilities.ts

@@ -2527,6 +2527,14 @@ export function getErrorSpanForNode(sourceFile: SourceFile, node: Node): TextSpa
         }
     }
 
+    if (node.parent !== undefined && node.parent.kind === SyntaxKind.ArrowFunction) {
+        const arrowFn = node.parent as ArrowFunction;
+        if (arrowFn.body === node && arrowFn.type !== undefined) {
+            const pos = skipTrivia(sourceFile.text, arrowFn.type.pos);
+            return getSpanOfTokenAtPosition(sourceFile, pos);
+        }
+    }
+
     if (errorNode === undefined) {
         // If we don't have a better node, then just set the error on the first token of
         // construct.

tests/baselines/reference/arrowFunctionReturnTypeErrorSpan.errors.txt

@@ -1,7 +1,7 @@
 arrowFunctionReturnTypeErrorSpan.ts(3,3): error TS2322: Type 'string' is not assignable to type 'number'.
-arrowFunctionReturnTypeErrorSpan.ts(7,25): error TS2322: Type 'string' is not assignable to type 'number'.
-arrowFunctionReturnTypeErrorSpan.ts(10,28): error TS2322: Type 'string' is not assignable to type 'number'.
 arrowFunctionReturnTypeErrorSpan.ts(12,25): error TS2304: Cannot find name 'missing'.
+arrowFunctionReturnTypeErrorSpan.ts(7,15): error TS2322: Type 'string' is not assignable to type 'number'.
+arrowFunctionReturnTypeErrorSpan.ts(10,15): error TS2322: Type 'string' is not assignable to type 'number'.
 
 
 ==== arrowFunctionReturnTypeErrorSpan.ts (4 errors) ====
@@ -14,12 +14,12 @@ arrowFunctionReturnTypeErrorSpan.ts(12,25): error TS2304: Cannot find name 'miss
 
     // expression body
     const b = (): number => "foo";
-                            ~~~~~
+                  ~~~~~~
 !!! error TS2322: Type 'string' is not assignable to type 'number'.
 
     type F<T> = T;
     const c = (): F<number> => "foo";
-                               ~~~~~
+                  ~
 !!! error TS2322: Type 'string' is not assignable to type 'number'.
 
     const d = (): number => missing;

tests/baselines/reference/conditionalTypes1.errors.txt

@@ -73,7 +73,7 @@ conditionalTypes1.ts(160,5): error TS2322: Type 'T' is not assignable to type 'Z
   Type 'string | number' is not assignable to type 'ZeroOf<T>'.
     Type 'string' is not assignable to type 'ZeroOf<T>'.
 conditionalTypes1.ts(263,9): error TS2403: Subsequent variable declarations must have the same type.  Variable 'z' must be of type 'T1', but here has type 'Foo<T & U>'.
-conditionalTypes1.ts(288,43): error TS2322: Type 'T95<U>' is not assignable to type 'T94<U>'.
+conditionalTypes1.ts(288,33): error TS2322: Type 'T95<U>' is not assignable to type 'T94<U>'.
   Type 'number | boolean' is not assignable to type 'T94<U>'.
     Type 'number' is not assignable to type 'T94<U>'.
       Type 'boolean' is not assignable to type 'true'.
@@ -465,7 +465,7 @@ conditionalTypes1.ts(288,43): error TS2322: Type 'T95<U>' is not assignable to t
     type T95<T> = T extends string ? boolean : number;
     const f44 = <U>(value: T94<U>): T95<U> => value;
     const f45 = <U>(value: T95<U>): T94<U> => value;  // Error
-                                              ~~~~~
+                                    ~~~
 !!! error TS2322: Type 'T95<U>' is not assignable to type 'T94<U>'.
 !!! error TS2322:   Type 'number | boolean' is not assignable to type 'T94<U>'.
 !!! error TS2322:     Type 'number' is not assignable to type 'T94<U>'.

tests/baselines/reference/mappedTypeConstraints2.errors.txt

@@ -6,7 +6,7 @@ mappedTypeConstraints2.ts(16,11): error TS2322: Type 'Mapped3<K>[Uppercase<K>]'
 mappedTypeConstraints2.ts(42,7): error TS2322: Type 'Mapped6<K>[keyof Mapped6<K>]' is not assignable to type '`_${string}`'.
   Type 'Mapped6<K>[string] | Mapped6<K>[number] | Mapped6<K>[symbol]' is not assignable to type '`_${string}`'.
     Type 'Mapped6<K>[string]' is not assignable to type '`_${string}`'.
-mappedTypeConstraints2.ts(51,57): error TS2322: Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'.
+mappedTypeConstraints2.ts(51,52): error TS2322: Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'.
   'T' could be instantiated with an arbitrary type which could be unrelated to 'Foo<T>[`get${T}`]'.
 mappedTypeConstraints2.ts(82,9): error TS2322: Type 'ObjectWithUnderscoredKeys<K>[`_${K}`]' is not assignable to type 'true'.
   Type 'ObjectWithUnderscoredKeys<K>[`_${string}`]' is not assignable to type 'true'.
@@ -75,7 +75,7 @@ mappedTypeConstraints2.ts(82,9): error TS2322: Type 'ObjectWithUnderscoredKeys<K
     };
 
     const get = <T extends string>(t: T, foo: Foo<T>): T => foo[`get${t}`];  // Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'
-                                                            ~~~~~~~~~~~~~~
+                                                       ~
 !!! error TS2322: Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'.
 !!! error TS2322:   'T' could be instantiated with an arbitrary type which could be unrelated to 'Foo<T>[`get${T}`]'.