cgen: fix codegen for indexing generic map (fix #23376) (#23402)

Author: felipensp

vlib/v/gen/c/assign.v

@@ -341,15 +341,13 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 						}
 						g.assign_ct_type = var_type
 					}
-				} else if val is ast.IndexExpr {
-					if val.left is ast.Ident && g.type_resolver.is_generic_param_var(val.left) {
-						ctyp := g.unwrap_generic(g.get_gn_var_type(val.left))
-						if ctyp != ast.void_type {
-							var_type = ctyp
-							val_type = var_type
-							left.obj.typ = var_type
-							g.assign_ct_type = var_type
-						}
+				} else if val is ast.IndexExpr && (val.left is ast.Ident && val.left.ct_expr) {
+					ctyp := g.unwrap_generic(g.type_resolver.get_type(val))
+					if ctyp != ast.void_type {
+						var_type = ctyp
+						val_type = var_type
+						left.obj.typ = var_type
+						g.assign_ct_type = var_type
 					}
 				} else if left.obj.ct_type_var == .generic_var && val is ast.CallExpr {
 					if val.return_type_generic != 0 && val.return_type_generic.has_flag(.generic) {

vlib/v/gen/c/fn.v

@@ -1353,27 +1353,6 @@ fn (mut g Gen) gen_to_str_method_call(node ast.CallExpr) bool {
 	return false
 }
 
-fn (mut g Gen) get_gn_var_type(var ast.Ident) ast.Type {
-	if g.cur_fn != unsafe { nil } && g.cur_fn.generic_names.len > 0 {
-		for k, cur_param in g.cur_fn.params {
-			if (k == 0 && g.cur_fn.is_method) || !cur_param.typ.has_flag(.generic)
-				|| var.name != cur_param.name {
-				continue
-			}
-			mut typ := cur_param.typ
-			mut cparam_type_sym := g.table.sym(g.unwrap_generic(typ))
-
-			if cparam_type_sym.kind == .array {
-				typ = g.unwrap_generic((cparam_type_sym.info as ast.Array).elem_type)
-			} else if cparam_type_sym.kind == .array_fixed {
-				typ = g.unwrap_generic((cparam_type_sym.info as ast.ArrayFixed).elem_type)
-			}
-			return typ
-		}
-	}
-	return ast.void_type
-}
-
 // resolve_return_type resolves the generic return type of CallExpr
 fn (mut g Gen) resolve_return_type(node ast.CallExpr) ast.Type {
 	if node.is_method {

vlib/v/tests/comptime/comptime_generic_map_test.v

@@ -0,0 +1,27 @@
+module main
+
+fn validate[T](values map[string]T, rules map[string][]string) ! {
+	for key, _ in rules {
+		value := values[key]!
+		assert typeof(value).name == T.name
+	}
+}
+
+fn test_main() {
+	validate({
+		'age': 31
+	}, {
+		'age': [
+			'required',
+		]
+	}) or { assert false }
+
+	validate({
+		'foo': 'bar'
+	}, {
+		'foo': [
+			'required',
+		]
+	}) or { assert false }
+	assert true
+}