feat(editor): colour global variables (the semantic global modifier) (#1393)

lua-language-server marks globals with the `global` token modifier, but
the editor dropped it, so a global variable looked like a local unless
rainbow highlighting was on. The modifier now sets `cm-sem-global`, drawn
in a new Language Defaults › Identifiers › Global variable colour
(`--syn-global`): library globals keep the predefined colour and calls the
function-call colour. Imported IntelliJ themes and .icls schemes take it
from DEFAULT_GLOBAL_VARIABLE. Built-in schemes default it to the local
variable colour (IntelliJ's fallback for the key), so they look as before
until a scheme sets it.

Fixes #1370

src/platform/colorScheme.ts

@@ -113,6 +113,7 @@ export const ATTRIBUTES: readonly AttributeDef[] = [
   syn("keyword", "Keyword", [LD], "keyword"),
   syn("identifier", "Identifiers › Local variable", [LD], "variable"),
   syn("parameter", "Identifiers › Parameter", [LD], "param"),
+  syn("globalVariable", "Identifiers › Global variable", [LD], "global"),
   syn("constant", "Identifiers › Constant", [LD], "constant"),
   syn("field", "Identifiers › Instance field", [LD], "property"),
   { id: "staticSymbol", name: "Identifiers › Static symbol", path: [LD], token: "static", italicOnly: true },

src/platform/icls.test.ts

@@ -41,6 +41,17 @@ describe(".icls schemes", () => {
     expect(customs).toEqual(before);
   });
 
+  it("imports the global variable colour", () => {
+    const xml =
+      '<scheme name="G" parent_scheme="Darcula"><attributes><option name="DEFAULT_GLOBAL_VARIABLE"><value>' +
+      '<option name="FOREGROUND" value="9876aa"/><option name="FONT_TYPE" value="2"/></value></option></attributes></scheme>';
+    expect(parseIcls(xml).scheme.attributes.globalVariable).toEqual({
+      foreground: "#9876aa",
+      bold: false,
+      italic: true,
+    });
+  });
+
   it.each([
     ["Darcula", "ffffff", "dark"],
     ["Default", "000000", "light"],

src/platform/icls.ts

@@ -11,6 +11,7 @@ const ATTRIBUTE_NAMES: Record<string, string> = {
   DEFAULT_IDENTIFIER: "identifier",
   DEFAULT_LOCAL_VARIABLE: "identifier",
   DEFAULT_PARAMETER: "parameter",
+  DEFAULT_GLOBAL_VARIABLE: "globalVariable",
   DEFAULT_CONSTANT: "constant",
   DEFAULT_INSTANCE_FIELD: "field",
   DEFAULT_STATIC_FIELD: "constant",