vkd3d-shader/preproc: Support namespaces in macro identifiers.

Approved-by: Elizabeth Figura (@zfigura)
Approved-by: Henri Verbeet (@hverbeet)
Merge-Request: https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/1096

libs/vkd3d-shader/preproc.l

@@ -66,7 +66,7 @@ static void update_location(struct preproc_ctx *ctx);
 
 NEWLINE         \r?\n
 WS              [ \t\r]
-IDENTIFIER      [A-Za-z_][A-Za-z0-9_]*
+IDENTIFIER      (::)?[A-Za-z_]((::)?[A-Za-z0-9_]+)*
 INT_SUFFIX      [uUlL]{0,2}
 
 %%

tests/preproc-macro.shader_test

@@ -317,3 +317,61 @@ KEY(pa)
 #define KEY KEY2(fa il)
 KEY
 pass
+
+[preproc]
+#define Key1::Key2 pass
+Key1::Key2
+
+[preproc]
+#define ::Key pass
+::Key
+
+[preproc]
+#define Key1::Key2(x) pass
+Key1::Key2(fail)
+
+[preproc]
+#define Key1::Key2::Key3 pass
+Key1::Key2::Key3
+
+[preproc]
+#define Key1:pass value
+Key1:pass
+
+[preproc]
+#define Key1::::pass value
+Key1::::pass
+
+[preproc]
+#define fail:: pass
+fail
+
+[preproc]
+#define pass bar
+#define key::bar fail
+key::pass
+
+[preproc]
+#define pass bar
+#define bar::key fail
+pass::key
+
+[preproc]
+#define fail::1KEY pass
+fail::1KEY
+
+[preproc]
+#define::pass value
+::pass
+
+[preproc]
+#define fail(key1::key2) key1::key2
+fail(pass)
+
+[preproc]
+#define key1:: key2 pass
+key1
+
+[preproc]
+#define key1 ::key2 pass
+key1