ast, parser: add additional pos info for FnDecl and InterfaceDecl nodes (#9603)

vlib/v/ast/ast.v

@@ -259,6 +259,7 @@ pub:
 pub struct InterfaceDecl {
 pub:
 	name         string
+	name_pos     token.Position
 	field_names  []string
 	is_pub       bool
 	methods      []FnDecl
@@ -365,7 +366,6 @@ pub:
 	language        Language
 	no_body         bool // just a definition `fn C.malloc()`
 	is_builtin      bool // this function is defined in builtin/strconv
-	pos             token.Position // function declaration position
 	body_pos        token.Position // function bodys position
 	file            string
 	generic_params  []GenericParam
@@ -373,15 +373,17 @@ pub:
 	attrs           []Attr
 	skip_gen        bool // this function doesn't need to be generated (for example [if foo])
 pub mut:
-	stmts         []Stmt
-	defer_stmts   []DeferStmt
-	return_type   Type
-	has_return    bool
-	comments      []Comment // comments *after* the header, but *before* `{`; used for InterfaceDecl
-	next_comments []Comment // coments that are one line after the decl; used for InterfaceDecl
-	source_file   &File = 0
-	scope         &Scope
-	label_names   []string
+	stmts           []Stmt
+	defer_stmts     []DeferStmt
+	return_type     Type
+	return_type_pos token.Position // `string` in `fn (u User) name() string` position
+	has_return      bool
+	comments        []Comment // comments *after* the header, but *before* `{`; used for InterfaceDecl
+	next_comments   []Comment // coments that are one line after the decl; used for InterfaceDecl
+	source_file     &File = 0
+	scope           &Scope
+	label_names     []string
+	pos             token.Position // function declaration position
 }
 
 pub struct GenericParam {
@@ -1603,7 +1605,7 @@ pub fn (node Node) position() token.Position {
 		StructField {
 			return node.pos.extend(node.type_pos)
 		}
-		MatchBranch, SelectBranch, EnumField, ConstField, StructInitField, GlobalField, Param {
+		MatchBranch, SelectBranch, EnumField, ConstField, StructInitField, GlobalField, CallArg {
 			return node.pos
 		}
 		IfBranch {
@@ -1625,6 +1627,9 @@ pub fn (node Node) position() token.Position {
 				}
 			}
 		}
+		Param {
+			return node.pos.extend(node.type_pos)
+		}
 		File {
 			mut pos := token.Position{}
 			if node.stmts.len > 0 {
@@ -1634,9 +1639,6 @@ pub fn (node Node) position() token.Position {
 			}
 			return pos
 		}
-		CallArg {
-			return node.pos
-		}
 	}
 }
 
@@ -1719,7 +1721,8 @@ pub fn (node Node) children() []Node {
 				children << node.expr
 			}
 			InterfaceDecl {
-				return node.methods.map(Node(Stmt(it)))
+				children << node.methods.map(Node(Stmt(it)))
+				children << node.fields.map(Node(it))
 			}
 			AssignStmt {
 				children << node.left.map(Node(it))

vlib/v/checker/checker.v

@@ -353,7 +353,7 @@ pub fn (mut c Checker) interface_decl(decl ast.InterfaceDecl) {
 	for method in decl.methods {
 		c.check_valid_snake_case(method.name, 'method name', method.pos)
 		if method.return_type != ast.Type(0) {
-			c.ensure_type_exists(method.return_type, method.pos) or { return }
+			c.ensure_type_exists(method.return_type, method.return_type_pos) or { return }
 		}
 		for param in method.params {
 			c.ensure_type_exists(param.typ, param.pos) or { return }

vlib/v/checker/tests/interface_return_parameter_err.out

@@ -1,8 +1,8 @@
-vlib/v/checker/tests/interface_return_parameter_err.vv:2:5: error: unknown type `Baz`.
+vlib/v/checker/tests/interface_return_parameter_err.vv:2:17: error: unknown type `Baz`.
 Did you mean `Foo`?
     1 | interface Foo {
     2 |     bar(string) []Baz
-      |     ~~~~~~~~~~~
+      |                 ~~~~~
     3 |     bar2(Bax) string
     4 | }
 vlib/v/checker/tests/interface_return_parameter_err.vv:3:10: error: unknown type `Bax`.

vlib/v/parser/fn.v

@@ -293,12 +293,14 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 		}
 	}
 	// Return type
+	mut return_type_pos := p.tok.position()
 	mut return_type := ast.void_type
 	// don't confuse token on the next line: fn decl, [attribute]
 	same_line := p.tok.line_nr == p.prev_tok.line_nr
 	if (p.tok.kind.is_start_of_type() && (same_line || p.tok.kind != .lsbr))
 		|| (same_line && p.tok.kind == .key_fn) {
 		return_type = p.parse_type()
+		return_type_pos = return_type_pos.extend(p.prev_tok.position())
 	}
 	mut type_sym_method_idx := 0
 	no_body := p.tok.kind != .lcbr
@@ -398,6 +400,7 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 		mod: p.mod
 		stmts: stmts
 		return_type: return_type
+		return_type_pos: return_type_pos
 		params: params
 		is_manualfree: is_manualfree
 		is_deprecated: is_deprecated
@@ -574,10 +577,12 @@ fn (mut p Parser) anon_fn() ast.AnonFn {
 	}
 	mut same_line := p.tok.line_nr == p.prev_tok.line_nr
 	mut return_type := ast.void_type
+	mut return_type_pos := p.tok.position()
 	// lpar: multiple return types
 	if same_line {
 		if p.tok.kind.is_start_of_type() {
 			return_type = p.parse_type()
+			return_type_pos = return_type_pos.extend(p.tok.position())
 		} else if p.tok.kind != .lcbr {
 			p.error_with_pos('expected return type, not $p.tok for anonymous function',
 				p.tok.position())
@@ -618,6 +623,7 @@ fn (mut p Parser) anon_fn() ast.AnonFn {
 			mod: p.mod
 			stmts: stmts
 			return_type: return_type
+			return_type_pos: return_type_pos
 			params: args
 			is_variadic: is_variadic
 			is_method: false

vlib/v/parser/struct.v

@@ -518,7 +518,10 @@ fn (mut p Parser) interface_decl() ast.InterfaceDecl {
 				scope: p.scope
 			}
 			if p.tok.kind.is_start_of_type() && p.tok.line_nr == line_nr {
+				method.return_type_pos = p.tok.position()
 				method.return_type = p.parse_type()
+				method.return_type_pos = method.return_type_pos.extend(p.tok.position())
+				method.pos = method.pos.extend(method.return_type_pos)
 			}
 			mcomments := p.eat_comments(same_line: true)
 			mnext_comments := p.eat_comments({})
@@ -577,5 +580,6 @@ fn (mut p Parser) interface_decl() ast.InterfaceDecl {
 		pos: pos
 		pre_comments: pre_comments
 		mut_pos: mut_pos
+		name_pos: name_pos
 	}
 }