Subject: bug#61205: 'function' in 3rd element of treesit-font-lock-feature-list

From: Dmitry Gutov <[email-masked]>
Date: Thu, 2 Feb 2023 04:34:44 +0200

On 01/02/2023 07:18, Yuan Fu wrote:
> 
> 
>> On Jan 31, 2023, at 6:08 PM, Dmitry Gutov <[email-masked]> wrote:
>>
>> X-Debbugs-Cc: Yuan Fu <[email-masked]>, Randy Taylor <[email-masked]>
>>
>> Some new built-in modes has 'function' feature highlighting thus enabled by default.
>>
>> rust-ts-mode, go-ts-mode, cmake-mode
>>
>> Should we move it to 4 for consistency with the rest?
>>
>> Previously, we talked about that and concluded that function calls are usually everywhere and are easy to notice without additional highlighting.
> 
> Right, I think they should be level 4.

OK, I tried simply changing that, and it turned out none of these modes 
have a 'definition' feature, so highlightings get stripped from all 
definitions as well.

And in a couple of cases function calls got highlighted either as a 
type, or as a property. I fixed the latter by deleting one selector, and 
the latter didn't touch per se.

But since the same modes had 'variable' and 'property' features in the 
3rd level as well, I moved them to the 4th (that resolved the incorrect 
highlighting as property mentioned above, but it's probably need to be 
improved later, in case someone will want to enable 'property' but not 
'function' highlighting).

And I added the 'definition' features and moved some highlighting rules 
there. And added some.

So the patch looks a bit more complex than expected, see attached.

cmake-ts-mode, in the end, I ended up keeping as-is. The 'variable' 
selector is more functional there than everywhere else (the grammar uses 
those nodes for template expansion), and if 'function' is removed, the 
buffer looks almost devoid of highlighting.

Also none of these modes have highlighting for function parameters or 
assignments. That can be improved later.

diff --git a/lisp/progmodes/go-ts-mode.el b/lisp/progmodes/go-ts-mode.el
index 5f3e1ea3e68..3536a6cb0cd 100644
--- a/lisp/progmodes/go-ts-mode.el
+++ b/lisp/progmodes/go-ts-mode.el
@@ -119,17 +119,27 @@ go-ts-mode--font-lock-settings
    :feature 'delimiter
    '((["," "." ";" ":"]) @font-lock-delimiter-face)
 
+   :language 'go
+   :feature 'definition
+   '((function_declaration
+      name: (identifier) @font-lock-function-name-face)
+     (method_declaration
+      name: (field_identifier) @font-lock-function-name-face)
+     (method_spec
+      name: (field_identifier) @font-lock-function-name-face))
+
+   :language 'go
+   :feature 'definition
+   '((field_declaration
+      name: (field_identifier) @font-lock-property-face))
+
    :language 'go
    :feature 'function
    '((call_expression
       function: (identifier) @font-lock-function-name-face)
      (call_expression
       function: (selector_expression
-                 field: (field_identifier) @font-lock-function-name-face))
-     (function_declaration
-      name: (identifier) @font-lock-function-name-face)
-     (method_declaration
-      name: (field_identifier) @font-lock-function-name-face))
+                 field: (field_identifier) @font-lock-function-name-face)))
 
    :language 'go
    :feature 'keyword
@@ -218,10 +228,10 @@ go-ts-mode
     (setq-local treesit-font-lock-settings go-ts-mode--font-lock-settings)
     (setq-local treesit-font-lock-feature-list
                 '(( comment)
-                  ( keyword string type)
-                  ( constant escape-sequence function label number
-                    property variable)
-                  ( bracket delimiter error operator)))
+                  ( keyword string type definition)
+                  ( constant escape-sequence label number)
+                  ( bracket delimiter error operator function variable
+                    property)))
 
     (treesit-major-mode-setup)))
 
diff --git a/lisp/progmodes/rust-ts-mode.el b/lisp/progmodes/rust-ts-mode.el
index e317793d211..20ee2e420d3 100644
--- a/lisp/progmodes/rust-ts-mode.el
+++ b/lisp/progmodes/rust-ts-mode.el
@@ -155,6 +155,16 @@ rust-ts-mode--font-lock-settings
    :feature 'delimiter
    '((["," "." ";" ":" "::"]) @font-lock-delimiter-face)
 
+   :language 'rust
+   :feature 'definition
+   '((function_item name: (identifier) @font-lock-function-name-face)
+     (macro_definition "macro_rules!" @font-lock-constant-face)
+     (macro_definition (identifier) @font-lock-preprocessor-face))
+
+   :language 'rust
+   :feature 'definition
+   '((field_declaration name: (field_identifier) @font-lock-property-face))
+
    :language 'rust
    :feature 'function
    '((call_expression
@@ -164,15 +174,12 @@ rust-ts-mode--font-lock-settings
         field: (field_identifier) @font-lock-function-name-face)
        (scoped_identifier
         name: (identifier) @font-lock-function-name-face)])
-     (function_item (identifier) @font-lock-function-name-face)
      (generic_function
       function: [(identifier) @font-lock-function-name-face
                  (field_expression
                   field: (field_identifier) @font-lock-function-name-face)
                  (scoped_identifier
                   name: (identifier) @font-lock-function-name-face)])
-     (macro_definition "macro_rules!" @font-lock-constant-face)
-     (macro_definition (identifier) @font-lock-preprocessor-face)
      (macro_invocation macro: (identifier) @font-lock-preprocessor-face))
 
    :language 'rust
@@ -208,7 +215,6 @@ rust-ts-mode--font-lock-settings
      (mod_item name: (identifier) @font-lock-constant-face)
      (primitive_type) @font-lock-type-face
      (type_identifier) @font-lock-type-face
-     (scoped_identifier name: (identifier) @font-lock-type-face)
      (scoped_identifier path: (identifier) @font-lock-constant-face)
      (scoped_identifier
       (scoped_identifier
@@ -318,10 +324,10 @@ rust-ts-mode
     (setq-local treesit-font-lock-settings rust-ts-mode--font-lock-settings)
     (setq-local treesit-font-lock-feature-list
                 '(( comment)
-                  ( keyword string)
+                  ( keyword string definition)
                   ( attribute builtin constant escape-sequence
-                    function number property type variable)
-                  ( bracket delimiter error operator)))
+                    number type)
+                  ( bracket delimiter error operator function property variable)))
 
     ;; Imenu.
     (setq-local treesit-simple-imenu-settings