checker: fix generics with multi generic struct types (#10808)

vlib/v/checker/checker.v

@@ -1968,6 +1968,13 @@ pub fn (mut c Checker) method_call(mut call_expr ast.CallExpr) ast.Type {
 	left_type := c.expr(call_expr.left)
 	c.expected_type = left_type
 	mut is_generic := left_type.has_flag(.generic)
+	// x is Bar<T>, x.foo() -> x.foo<T>()
+	if is_generic && call_expr.concrete_types.len == 0 {
+		rec_sym := c.table.get_type_symbol(left_type)
+		if rec_sym.info is ast.Struct {
+			call_expr.concrete_types = rec_sym.info.generic_types
+		}
+	}
 	call_expr.left_type = left_type
 	// Set default values for .return_type & .receiver_type too,
 	// or there will be hard to diagnose 0 type panics in cgen.

vlib/v/gen/c/fn.v

@@ -831,6 +831,7 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 	// left & left_type will be `x` and `x type` in `x.fieldfn()`
 	// will be `0` for `foo()`
 	mut is_interface_call := false
+	mut is_selector_call := false
 	if node.left_type != 0 {
 		left_sym := g.table.get_type_symbol(node.left_type)
 		if left_sym.kind == .interface_ {
@@ -843,6 +844,7 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 		} else {
 			g.write('.')
 		}
+		is_selector_call = true
 	}
 	mut name := node.name
 	is_print := name in ['print', 'println', 'eprint', 'eprintln', 'panic']
@@ -914,7 +916,9 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 			panic('cgen: obf name "$key" not found, this should never happen')
 		}
 	}
-	name = g.generic_fn_name(node.concrete_types, name, false)
+	if !is_selector_call {
+		name = g.generic_fn_name(node.concrete_types, name, false)
+	}
 	// TODO2
 	// cgen shouldn't modify ast nodes, this should be moved
 	// g.generate_tmp_autofree_arg_vars(node, name)

vlib/v/tests/generics_with_multi_generics_struct_types_test.v

@@ -0,0 +1,19 @@
+struct Animal<T> {
+	metadata T
+}
+
+fn (a Animal<T>) get<T>() T {
+	return a.metadata
+}
+
+fn extract<T>(x Animal<T>) T {
+	return x.get()
+}
+
+fn test_generics_with_multi_generic_struct_types() {
+	a := Animal<int>{123}
+	b := Animal<string>{'456'}
+
+	assert extract<int>(a) == 123
+	assert extract<string>(b) == '456'
+}