From eed496d0bcd2a5171bbcecc9af5a2764b95891ca Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Sun, 17 Jul 2022 23:09:15 +0800
Subject: [PATCH] checker: check generic struct declaration (#15106)

---
 vlib/v/checker/struct.v                       | 24 +++++++++++++++++++
 .../generics_struct_decl_no_mention_err.out   | 14 +++++++++++
 .../generics_struct_decl_no_mention_err.vv    | 10 ++++++++
 3 files changed, 48 insertions(+)
 create mode 100644 vlib/v/checker/tests/generics_struct_decl_no_mention_err.out
 create mode 100644 vlib/v/checker/tests/generics_struct_decl_no_mention_err.vv

diff --git a/vlib/v/checker/struct.v b/vlib/v/checker/struct.v
index 4ef9b675f5..40f298be5d 100644
--- a/vlib/v/checker/struct.v
+++ b/vlib/v/checker/struct.v
@@ -24,6 +24,18 @@ pub fn (mut c Checker) struct_decl(mut node ast.StructDecl) {
 					struct_sym.info.is_heap = true
 				}
 			}
+			// Ensure each generic type of the embed was declared in the struct's definition
+			if node.generic_types.len > 0 && embed.typ.has_flag(.generic) {
+				embed_generic_names := c.table.generic_type_names(embed.typ)
+				node_generic_names := node.generic_types.map(c.table.type_to_str(it))
+				for name in embed_generic_names {
+					if name !in node_generic_names {
+						struct_generic_names := node_generic_names.join(', ')
+						c.error('generic type name `$name` is not mentioned in struct `$node.name<$struct_generic_names>`',
+							embed.pos)
+					}
+				}
+			}
 		}
 		if struct_sym.info.is_minify {
 			node.fields.sort_with_compare(minify_sort_fn)
@@ -122,6 +134,18 @@ pub fn (mut c Checker) struct_decl(mut node ast.StructDecl) {
 					}
 				}
 			}
+			// Ensure each generic type of the field was declared in the struct's definition
+			if node.generic_types.len > 0 && field.typ.has_flag(.generic) {
+				field_generic_names := c.table.generic_type_names(field.typ)
+				node_generic_names := node.generic_types.map(c.table.type_to_str(it))
+				for name in field_generic_names {
+					if name !in node_generic_names {
+						struct_generic_names := node_generic_names.join(', ')
+						c.error('generic type name `$name` is not mentioned in struct `$node.name<$struct_generic_names>`',
+							field.type_pos)
+					}
+				}
+			}
 		}
 		if node.generic_types.len == 0 && has_generic_types {
 			c.error('generic struct declaration must specify the generic type names, e.g. Foo<T>',
diff --git a/vlib/v/checker/tests/generics_struct_decl_no_mention_err.out b/vlib/v/checker/tests/generics_struct_decl_no_mention_err.out
new file mode 100644
index 0000000000..163688e135
--- /dev/null
+++ b/vlib/v/checker/tests/generics_struct_decl_no_mention_err.out
@@ -0,0 +1,14 @@
+vlib/v/checker/tests/generics_struct_decl_no_mention_err.vv:4:2: error: generic type name `T` is not mentioned in struct `Foo<U>`
+    2 |
+    3 | struct Foo<U> {
+    4 |     Bar<T>
+      |     ~~~~~~
+    5 |     foo U
+    6 |     bar P
+vlib/v/checker/tests/generics_struct_decl_no_mention_err.vv:6:6: error: generic type name `P` is not mentioned in struct `Foo<U>`
+    4 |     Bar<T>
+    5 |     foo U
+    6 |     bar P
+      |         ^
+    7 | }
+    8 |
diff --git a/vlib/v/checker/tests/generics_struct_decl_no_mention_err.vv b/vlib/v/checker/tests/generics_struct_decl_no_mention_err.vv
new file mode 100644
index 0000000000..b2573ca46c
--- /dev/null
+++ b/vlib/v/checker/tests/generics_struct_decl_no_mention_err.vv
@@ -0,0 +1,10 @@
+fn main() {}
+
+struct Foo<U> {
+	Bar<T>
+	foo U
+	bar P
+}
+
+struct Bar<T> {
+}