feat(theming): separate highlight for function declarations

Add separate highlighting scope for function (and method) declarations
that allows styling the declarations differently from their calls.

Author: matoous

book/src/themes.md

@@ -193,8 +193,9 @@ We use a similar set of scopes as
 - `operator` - `||`, `+=`, `>`
 
 - `function`
-  - `builtin`
-  - `method`
+  - `declaration` - Declaration of a function (e.g. `fn foo() { }` in Rust)
+  - `builtin` - Built-in functions (e.q. `println!` in Rust)
+  - `method` - Methods
   - `macro`
   - `special` (preprocessor in C)
 

runtime/queries/c/highlights.scm

@@ -109,13 +109,13 @@
 (char_literal) @constant.character
 
 (call_expression
-  function: (identifier) @function)
+  function: (identifier) @function.declaration)
 (call_expression
   function: (field_expression
-    field: (field_identifier) @function))
+    field: (field_identifier) @function.declaration))
 (call_expression (argument_list (identifier) @variable))
 (function_declarator
-  declarator: [(identifier) (field_identifier)] @function)
+  declarator: [(identifier) (field_identifier)] @function.declaration)
 (parameter_declaration
   declarator: (identifier) @variable.parameter)
 (parameter_declaration

runtime/queries/ecma/highlights.scm

@@ -26,9 +26,9 @@
 (function
   name: (identifier) @function)
 (function_declaration
-  name: (identifier) @function)
+  name: (identifier) @function.declaration)
 (method_definition
-  name: (property_identifier) @function.method)
+  name: (property_identifier) @function.declaration)
 
 (pair
   key: (property_identifier) @function.method

runtime/queries/go/highlights.scm

@@ -14,10 +14,10 @@
 ; Function definitions
 
 (function_declaration
-  name: (identifier) @function)
+  name: (identifier) @function.declaration)
 
 (method_declaration
-  name: (field_identifier) @function.method)
+  name: (field_identifier) @function.declaration)
 
 ; Identifiers
 

runtime/queries/rust/highlights.scm

@@ -263,10 +263,10 @@
   ])
 
 (function_item
-  name: (identifier) @function)
+  name: (identifier) @function.declaration)
 
 (function_signature_item
-  name: (identifier) @function)
+  name: (identifier) @function.declaration)
 
 ; ---
 ; Macros

runtime/themes/fleet_dark.toml

@@ -32,7 +32,7 @@
 "keyword.control.exception" = "purple"
 "operator" = "light"
 "function" = "yellow"
-"function.macro" = "green"
+"function.declaration" = { fg = "lightest", modifiers = ["bold"] }
 "function.builtin" = "green"
 "function.special" = "green"
 "function.method" = "light"