From dd2002cc57d2029f2441ad52c3f10f3641bce278 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Fri, 23 Apr 2021 20:17:57 +0800
Subject: [PATCH] cgen: fix generics with multi generics struct receiver
 (#9853)

---
 vlib/v/ast/table.v                            |  2 +-
 vlib/v/ast/types.v                            |  1 +
 vlib/v/checker/check_types.v                  |  8 ++++--
 vlib/v/checker/checker.v                      |  4 +--
 vlib/v/gen/c/cgen.v                           |  4 +--
 vlib/v/parser/struct.v                        |  1 +
 ...h_multiple_generics_struct_receiver_test.v | 28 +++++++++++++++++++
 7 files changed, 40 insertions(+), 8 deletions(-)
 create mode 100644 vlib/v/tests/generics_with_multiple_generics_struct_receiver_test.v

diff --git a/vlib/v/ast/table.v b/vlib/v/ast/table.v
index 17696d30f8..78fc2e9e54 100644
--- a/vlib/v/ast/table.v
+++ b/vlib/v/ast/table.v
@@ -1075,7 +1075,7 @@ pub fn (mut t Table) generic_struct_insts_to_concrete() {
 						fields[i].typ = t_typ
 					}
 				}
-				parent_info.generic_types = []
+				parent_info.is_generic = false
 				parent_info.concrete_types = info.concrete_types.clone()
 				parent_info.fields = fields
 				parent_info.parent_type = new_type(info.parent_idx).set_flag(.generic)
diff --git a/vlib/v/ast/types.v b/vlib/v/ast/types.v
index a8081ee9d9..d3337094f0 100644
--- a/vlib/v/ast/types.v
+++ b/vlib/v/ast/types.v
@@ -722,6 +722,7 @@ pub mut:
 	is_typedef     bool // C. [typedef]
 	is_union       bool
 	is_heap        bool
+	is_generic     bool
 	generic_types  []Type
 	concrete_types []Type
 	parent_type    Type
diff --git a/vlib/v/checker/check_types.v b/vlib/v/checker/check_types.v
index cc63a40710..eb7aca18f8 100644
--- a/vlib/v/checker/check_types.v
+++ b/vlib/v/checker/check_types.v
@@ -486,13 +486,15 @@ pub fn (mut c Checker) infer_fn_generic_types(f ast.Fn, mut call_expr ast.CallEx
 		mut typ := ast.void_type
 		for i, param in f.params {
 			mut to_set := ast.void_type
-			// resolve generic struct receiver (TODO: multi generic struct)
+			// resolve generic struct receiver
 			if i == 0 && call_expr.is_method && param.typ.has_flag(.generic) {
 				sym := c.table.get_type_symbol(call_expr.receiver_type)
 				if sym.kind == .struct_ {
 					info := sym.info as ast.Struct
-					if info.concrete_types.len > 0 {
-						typ = info.concrete_types[0]
+					receiver_generic_names := info.generic_types.map(c.table.get_type_symbol(it).name)
+					if gt_name in receiver_generic_names {
+						idx := receiver_generic_names.index(gt_name)
+						typ = info.concrete_types[idx]
 					}
 				}
 			}
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index a2c6fcc636..7ac9fa1d00 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1433,7 +1433,7 @@ fn (mut c Checker) check_map_and_filter(is_map bool, elem_typ ast.Type, call_exp
 fn (mut c Checker) check_return_generics_struct(return_type ast.Type, mut call_expr ast.CallExpr, generic_types []ast.Type) {
 	rts := c.table.get_type_symbol(return_type)
 	if rts.info is ast.Struct {
-		if rts.info.generic_types.len > 0 {
+		if rts.info.is_generic {
 			mut nrt := '$rts.name<'
 			mut c_nrt := '${rts.name}_T_'
 			for i in 0 .. call_expr.generic_types.len {
@@ -1462,7 +1462,7 @@ fn (mut c Checker) check_return_generics_struct(return_type ast.Type, mut call_e
 						}
 					}
 					mut info := rts.info
-					info.generic_types = []
+					info.is_generic = false
 					info.concrete_types = generic_types.clone()
 					info.parent_type = return_type
 					info.fields = fields
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 90c37c7ba4..2d9cc57d17 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -693,7 +693,7 @@ fn (mut g Gen) cc_type(typ ast.Type, is_prefix_struct bool) string {
 	mut styp := sym.cname
 	// TODO: this needs to be removed; cgen shouldn't resolve generic types (job of checker)
 	if mut sym.info is ast.Struct {
-		if sym.info.generic_types.len > 0 {
+		if sym.info.is_generic {
 			mut sgtyps := '_T'
 			for gt in sym.info.generic_types {
 				gts := g.table.get_type_symbol(g.unwrap_generic(gt))
@@ -5438,7 +5438,7 @@ fn (mut g Gen) write_types(types []ast.TypeSymbol) {
 		mut name := typ.cname
 		match mut typ.info {
 			ast.Struct {
-				if typ.info.generic_types.len > 0 {
+				if typ.info.is_generic {
 					continue
 				}
 				if name.contains('_T_') {
diff --git a/vlib/v/parser/struct.v b/vlib/v/parser/struct.v
index 02939b3ad8..9d8081874b 100644
--- a/vlib/v/parser/struct.v
+++ b/vlib/v/parser/struct.v
@@ -299,6 +299,7 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 			is_typedef: attrs.contains('typedef')
 			is_union: is_union
 			is_heap: attrs.contains('heap')
+			is_generic: generic_types.len > 0
 			generic_types: generic_types
 			attrs: attrs
 		}
diff --git a/vlib/v/tests/generics_with_multiple_generics_struct_receiver_test.v b/vlib/v/tests/generics_with_multiple_generics_struct_receiver_test.v
new file mode 100644
index 0000000000..1307e2640d
--- /dev/null
+++ b/vlib/v/tests/generics_with_multiple_generics_struct_receiver_test.v
@@ -0,0 +1,28 @@
+struct Foo<A, B> {
+	a A
+	b B
+}
+
+fn (num Foo<A, B>) get_foo1<A, B>() (A, B) {
+	return num.a, num.b
+}
+
+fn (num Foo<A, B>) get_foo2<B, A>() (A, B) {
+	return num.a, num.b
+}
+
+fn test_generics_with_multi_generics_struct_receiver() {
+	num := Foo<int,string>{
+		a: 3
+		b: 'aaa'
+	}
+	a1, b1 := num.get_foo1()
+	println('$a1, $b1')
+	assert a1 == 3
+	assert b1 == 'aaa'
+
+	a2, b2 := num.get_foo2()
+	println('$a2, $b2')
+	assert a2 == 3
+	assert b2 == 'aaa'
+}