font-lock: highlight "foreign import" if no further text

Prior to this commit a valid code like

    foreign import
        foo

wasn't getting correctly highlighted. This fixes it.

While doing so, we also remove all the ccall/stdcall/etc stuff, which
is a legacy from haskell-mode and doesn't exist in purescript.

Author: Hi-Angel

purescript-font-lock.el

@@ -223,13 +223,10 @@ Returns keywords suitable for `font-lock-keywords'."
              (4 (symbol-value 'purescript-keyword-face) nil lax))
 
             (,reservedsym 1 (symbol-value 'purescript-operator-face))
-            ;; Special case for `foreign import'
-            ;; keywords in foreign import statements but are not otherwise reserved.
-            ("\\<\\(foreign\\)[ \t]+\\(import\\)[ \t]+\\(?:\\(ccall\\|stdcall\\|cplusplus\\|jvm\\|dotnet\\)[ \t]+\\)?\\(?:\\(safe\\|unsafe\\|interruptible\\)[ \t]+\\)?"
+            ;; Case for `foreign import'
+            ("\\<\\(foreign\\)[ \t]+\\(import\\>\\)"
              (1 (symbol-value 'purescript-keyword-face) nil lax)
-             (2 (symbol-value 'purescript-keyword-face) nil lax)
-             (3 (symbol-value 'purescript-keyword-face) nil lax)
-             (4 (symbol-value 'purescript-keyword-face) nil lax))
+             (2 (symbol-value 'purescript-keyword-face) nil lax))
 
             (,reservedsym 1 (symbol-value 'purescript-operator-face))
             ;; Special case for `foreign export'

tests/purescript-font-lock-tests.el

@@ -303,3 +303,49 @@ derive newtype instance foldableNonEmptyList :: Foldable NonEmptyList
      (449 450 font-lock-variable-name-face) (451 451 nil)
      (452 459 font-lock-type-face) (460 460 nil)
      (461 472 font-lock-type-face) (473 473 nil))))
+
+(ert-deftest foreign-imports ()
+  (purescript-test-ranges
+   "foreign import func2 :: Effect Int
+foreign import func3
+  :: Effect Int
+foreign import
+  func4 :: Effect Int
+  foreign import func5 -- invalid indentation, but allowed in other context
+"
+   '((1 7 font-lock-keyword-face)
+     (8 8 nil)
+     (9 14 font-lock-keyword-face)
+     (15 21 nil)
+     (22 23 font-lock-variable-name-face)
+     (24 24 nil)
+     (25 30 font-lock-type-face)
+     (31 31 nil)
+     (32 34 font-lock-type-face)
+     (35 35 nil)
+     (36 42 font-lock-keyword-face)
+     (43 43 nil)
+     (44 49 font-lock-keyword-face)
+     (50 58 nil)
+     (59 60 font-lock-variable-name-face)
+     (61 61 nil)
+     (62 67 font-lock-type-face)
+     (68 68 nil)
+     (69 71 font-lock-type-face)
+     (72 72 nil)
+     (73 79 font-lock-keyword-face)
+     (80 80 nil)
+     (81 86 font-lock-keyword-face)
+     (87 95 nil)
+     (96 97 font-lock-variable-name-face)
+     (98 98 nil)
+     (99 104 font-lock-type-face)
+     (105 105 nil)
+     (106 108 font-lock-type-face)
+     (109 111 nil)
+     (112 118 font-lock-keyword-face)
+     (119 119 nil)
+     (120 125 font-lock-keyword-face)
+     (126 132 nil)
+     (133 135 font-lock-comment-delimiter-face)
+     (136 185 font-lock-comment-face))))