fix(fontlock): fontify return type in a function type definition

Author: Fuco1

typescript-mode-general-tests.el

@@ -565,7 +565,11 @@ should be fontified as variable, keyword and type."
   (test-with-fontified-buffer
       "private genericArray3: SomeType<Foo[]>[];"
     (should (eq (get-face-at "SomeType") 'font-lock-type-face))
-    (should (eq (get-face-at "Foo") 'font-lock-type-face))))
+    (should (eq (get-face-at "Foo") 'font-lock-type-face)))
+
+  (test-with-fontified-buffer
+      "const f: () => SomeType = () => {}"
+    (should (eq (get-face-at "SomeType") 'font-lock-type-face))))
 
 (ert-deftest font-lock/type-names-level4-namespaces ()
   "Namespaced Typenames should be highlighted in declarations"

typescript-mode.el

@@ -2003,9 +2003,10 @@ This performs fontification according to `typescript--class-styles'."
     ;; - private genericArray: SomeType<Foo>[]
     ;; - function testFunc(): SomeType<> {
     ;; - function testFunc(a): a is SomeType<> {
+    ;; - () => SomeType
     ;; TODO: namespaced classes!
     ,(list
-      (concat ":\\s-\\(?:\\s-*\\(" typescript--name-re "\\)\\s-*\\(is\\)\\s-*\\)?" "\\(" typescript--type-name-re "\\)\\(<" typescript--type-name-re ">\\)?\\(\[\]\\)?\\([,;]\\)?\\s-*{?")
+      (concat "\\(?::\\|=>\\)\\s-\\(?:\\s-*\\(" typescript--name-re "\\)\\s-*\\(is\\)\\s-*\\)?" "\\(" typescript--type-name-re "\\)\\(<" typescript--type-name-re ">\\)?\\(\[\]\\)?\\([,;]\\)?\\s-*{?")
       '(1 'font-lock-variable-name-face nil t)
       '(2 'font-lock-keyword-face nil t)
       '(3 'font-lock-type-face))