checker: fix generics with nested external generics fn (#9933)

vlib/v/checker/checker.v

@@ -197,6 +197,8 @@ pub fn (mut c Checker) check_files(ast_files []ast.File) {
 	// post process generic functions. must be done after all files have been
 	// checked, to eunsure all generic calls are processed as this information
 	// is needed when the generic type is auto inferred from the call argument
+	// Check 2 times (in order to check nested generics fn)
+	for _ in 0 .. 2 {
 		for i in 0 .. ast_files.len {
 			file := unsafe { &ast_files[i] }
 			if file.generic_fns.len > 0 {
@@ -204,6 +206,7 @@ pub fn (mut c Checker) check_files(ast_files []ast.File) {
 				c.post_process_generic_fns()
 			}
 		}
+	}
 	// restore the original c.file && c.mod after post processing
 	c.change_current_file(last_file)
 	c.timers.show('checker_post_process_generic_fns')
@@ -1990,7 +1993,7 @@ pub fn (mut c Checker) fn_call(mut call_expr ast.CallExpr) ast.Type {
 		}
 	}
 	if has_generic {
-		if c.mod != '' && !fn_name.starts_with('${c.mod}.') {
+		if c.mod != '' && !fn_name.contains('.') {
 			// Need to prepend the module when adding a generic type to a function
 			c.table.register_fn_concrete_types(c.mod + '.' + fn_name, concrete_types)
 		} else {
@@ -6573,8 +6576,6 @@ fn (mut c Checker) fetch_and_verify_orm_fields(info ast.Struct, pos token.Positi
 fn (mut c Checker) post_process_generic_fns() {
 	// Loop thru each generic function concrete type.
 	// Check each specific fn instantiation.
-	// Check 2 times (in order to check nested generics fn)
-	for _ in 0 .. 2 {
 	for i in 0 .. c.file.generic_fns.len {
 		if c.table.fn_generic_types.len == 0 {
 			// no concrete types, so just skip:
@@ -6592,7 +6593,6 @@ fn (mut c Checker) post_process_generic_fns() {
 		node.cur_generic_types = []
 	}
 }
-}
 
 fn (mut c Checker) fn_decl(mut node ast.FnDecl) {
 	c.returns = false

vlib/v/tests/generics_with_nested_external_generics_fn_test.v

@@ -0,0 +1,21 @@
+import rand.util
+import rand
+
+pub fn sample<T>(arr []T, k int) []T {
+	mut result := arr.clone()
+
+	rand.seed([u32(1), 2]) // set seed to produce same results in order
+	util.shuffle<T>(mut result, k)
+
+	return result[0..k]
+}
+
+fn test_generics_with_nested_external_generics_fn() {
+	mut arr := [11, 32, 24, 45, 57, 32, 37, 52, 37, 24]
+	println(arr)
+
+	ret := sample<int>(arr, 5)
+	println(ret)
+
+	assert ret == [32, 45, 57, 11, 37]
+}