parser: disallow using generic functions as a field type name inside struct decl (fix #25452) (#25705)

Delta456 · web-flow · commit 8ef3db5874a0 · 2025-11-10T08:55:37.000+02:00
diff --git a/vlib/v/parser/parse_type.v b/vlib/v/parser/parse_type.v
@@ -617,6 +617,7 @@ If you need to modify an array in a function, use a mutable argument instead: `f
 }
 
 fn (mut p Parser) parse_any_type(language ast.Language, is_ptr bool, check_dot bool, is_option bool) ast.Type {
+	name_pos := p.tok.pos()
 	mut name := p.tok.lit
 	if language == .c {
 		name = 'C.${name}'
@@ -779,7 +780,7 @@ fn (mut p Parser) parse_any_type(language ast.Language, is_ptr bool, check_dot b
 							return p.parse_generic_type(name)
 						}
 						if p.tok.kind in [.lt, .lsbr] && p.tok.is_next_to(p.prev_tok) {
-							return p.parse_generic_inst_type(name)
+							return p.parse_generic_inst_type(name, name_pos)
 						}
 						return p.find_type_or_add_placeholder(name, language)
 					}
@@ -904,7 +905,7 @@ fn (mut p Parser) parse_generic_type(name string) ast.Type {
 	return ast.new_type(idx).set_flag(.generic)
 }
 
-fn (mut p Parser) parse_generic_inst_type(name string) ast.Type {
+fn (mut p Parser) parse_generic_inst_type(name string, name_pos token.Pos) ast.Type {
 	p.generic_type_level++
 	defer {
 		p.generic_type_level--
@@ -999,7 +1000,13 @@ fn (mut p Parser) parse_generic_inst_type(name string) ast.Type {
 						concrete_types_pos)
 				}
 			}
-			else {}
+			else {
+				// Disallow generic function as type inside struct decl
+				if parent_sym.kind == .placeholder && p.inside_struct_field_decl
+					&& !parent_sym.name.all_after_last('.')[0].is_capital() {
+					p.error_with_pos('unknown type `${parent_sym.name}`', name_pos)
+				}
+			}
 		}
 
 		idx := p.table.register_sym(ast.TypeSymbol{
diff --git a/vlib/v/parser/tests/generic_imp_symbol_struct_field_err.out b/vlib/v/parser/tests/generic_imp_symbol_struct_field_err.out
@@ -0,0 +1,6 @@
+vlib/v/parser/tests/generic_imp_symbol_struct_field_err.vv:4:8: error: unknown type `math.vec.vec3`
+    2 | 
+    3 | struct Veca {
+    4 |     field vec3[f64]
+      |           ~~~~
+    5 | }
diff --git a/vlib/v/parser/tests/generic_imp_symbol_struct_field_err.vv b/vlib/v/parser/tests/generic_imp_symbol_struct_field_err.vv
@@ -0,0 +1,5 @@
+import math.vec { vec3 }
+
+struct Veca {
+	field vec3[f64]
+}

Original file line number	Diff line number	Diff line change
@@ -617,6 +617,7 @@ If you need to modify an array in a function, use a mutable argument instead: `f
`617`	`617`	`}`
`618`	`618`
`619`	`619`	`fn (mut p Parser) parse_any_type(language ast.Language, is_ptr bool, check_dot bool, is_option bool) ast.Type {`
	`620`	`+ name_pos := p.tok.pos()`
`620`	`621`	`mut name := p.tok.lit`
`621`	`622`	`if language == .c {`
`622`	`623`	`name = 'C.${name}'`
`@@ -779,7 +780,7 @@ fn (mut p Parser) parse_any_type(language ast.Language, is_ptr bool, check_dot b`
`779`	`780`	`return p.parse_generic_type(name)`
`780`	`781`	`}`
`781`	`782`	`if p.tok.kind in [.lt, .lsbr] && p.tok.is_next_to(p.prev_tok) {`
`782`		`- return p.parse_generic_inst_type(name)`
	`783`	`+ return p.parse_generic_inst_type(name, name_pos)`
`783`	`784`	`}`
`784`	`785`	`return p.find_type_or_add_placeholder(name, language)`
`785`	`786`	`}`
`@@ -904,7 +905,7 @@ fn (mut p Parser) parse_generic_type(name string) ast.Type {`
`904`	`905`	`return ast.new_type(idx).set_flag(.generic)`
`905`	`906`	`}`
`906`	`907`
`907`		`-fn (mut p Parser) parse_generic_inst_type(name string) ast.Type {`
	`908`	`+fn (mut p Parser) parse_generic_inst_type(name string, name_pos token.Pos) ast.Type {`
`908`	`909`	`p.generic_type_level++`
`909`	`910`	`defer {`
`910`	`911`	`p.generic_type_level--`
`@@ -999,7 +1000,13 @@ fn (mut p Parser) parse_generic_inst_type(name string) ast.Type {`
`999`	`1000`	`concrete_types_pos)`
`1000`	`1001`	`}`
`1001`	`1002`	`}`
`1002`		`- else {}`
	`1003`	`+ else {`
	`1004`	`+ // Disallow generic function as type inside struct decl`
	`1005`	`+ if parent_sym.kind == .placeholder && p.inside_struct_field_decl`
	`1006`	`+ && !parent_sym.name.all_after_last('.')[0].is_capital() {`
	`1007`	+ p.error_with_pos('unknown type `${parent_sym.name}`', name_pos)
	`1008`	`+ }`
	`1009`	`+ }`
`1003`	`1010`	`}`
`1004`	`1011`
`1005`	`1012`	`idx := p.table.register_sym(ast.TypeSymbol{`