all: allow defer use from other scope (#10284)

vlib/v/ast/ast.v

@@ -629,6 +629,7 @@ pub:
 	tok_kind token.Kind
 	pos      token.Position
 	mut_pos  token.Position
+	comptime bool
 pub mut:
 	scope  &Scope
 	obj    ScopeObject
@@ -983,6 +984,7 @@ pub:
 	stmts []Stmt
 	pos   token.Position
 pub mut:
+	defer_vars []Ident
 	ifdef      string
 	idx_in_fn  int = -1 // index in FnDecl.defer_stmts
 }

vlib/v/checker/checker.v

@@ -3955,6 +3955,29 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 			if c.locked_names.len != 0 || c.rlocked_names.len != 0 {
 				c.error('defers are not allowed in lock statements', node.pos)
 			}
+			for i, ident in node.defer_vars {
+				mut id := ident
+				if id.info is ast.IdentVar {
+					if id.comptime && (id.name in checker.valid_comp_if_compilers
+						|| id.name in checker.valid_comp_if_os
+						|| id.name in checker.valid_comp_if_other
+						|| id.name in checker.valid_comp_if_platforms) {
+						node.defer_vars[i] = ast.Ident{
+							scope: 0
+							name: ''
+						}
+						continue
+					}
+					mut info := id.info as ast.IdentVar
+					typ := c.ident(mut id)
+					if typ == ast.error_type_idx {
+						continue
+					}
+					info.typ = typ
+					id.info = info
+					node.defer_vars[i] = id
+				}
+			}
 			c.stmts(node.stmts)
 		}
 		ast.EnumDecl {

vlib/v/gen/c/cgen.v

@@ -174,6 +174,8 @@ mut:
 	obf_table          map[string]string
 	// main_fn_decl_node  ast.FnDecl
 	expected_cast_type ast.Type // for match expr of sumtypes
+	defer_vars         []string
+	anon_fn            bool
 }
 
 pub fn gen(files []&ast.File, table &ast.Table, pref &pref.Preferences) string {
@@ -2248,7 +2250,11 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 			g.writeln(';')
 			for i, lx in assign_stmt.left {
 				mut is_auto_heap := false
+				mut ident := ast.Ident{
+					scope: 0
+				}
 				if lx is ast.Ident {
+					ident = lx
 					if lx.kind == .blank_ident {
 						continue
 					}
@@ -2256,7 +2262,11 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 						is_auto_heap = lx.obj.is_auto_heap
 					}
 				}
-				styp := g.typ(assign_stmt.left_types[i])
+				styp := if ident.name in g.defer_vars {
+					''
+				} else {
+					g.typ(assign_stmt.left_types[i])
+				}
 				if assign_stmt.op == .decl_assign {
 					g.write('$styp ')
 					if is_auto_heap {
@@ -2403,7 +2413,7 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 				is_auto_heap = left.obj.is_auto_heap
 			}
 		}
-		styp := g.typ(var_type)
+		styp := if ident.name in g.defer_vars { '' } else { g.typ(var_type) }
 		mut is_fixed_array_init := false
 		mut has_val := false
 		match val {
@@ -2946,7 +2956,9 @@ fn (mut g Gen) autofree_var_call(free_fn_name string, v ast.Var) {
 fn (mut g Gen) gen_anon_fn_decl(mut node ast.AnonFn) {
 	if !node.has_gen {
 		pos := g.out.len
+		g.anon_fn = true
 		g.stmt(node.decl)
+		g.anon_fn = false
 		fn_body := g.out.after(pos)
 		g.out.go_back(fn_body.len)
 		g.anon_fn_definitions << fn_body

vlib/v/gen/c/fn.v

@@ -103,6 +103,18 @@ fn (mut g Gen) gen_fn_decl(node &ast.FnDecl, skip bool) {
 		// || node.no_body {
 		return
 	}
+
+	tmp_defer_vars := g.defer_vars // must be here because of workflow
+	if !g.anon_fn {
+		g.defer_vars = []string{}
+	} else {
+		if node.defer_stmts.len > 0 {
+			g.defer_vars = []string{}
+			defer {
+				g.defer_vars = tmp_defer_vars
+			}
+		}
+	}
 	// Skip [if xxx] if xxx is not defined
 	/*
 	for attr in node.attrs {
@@ -265,6 +277,18 @@ fn (mut g Gen) gen_fn_decl(node &ast.FnDecl, skip bool) {
 	g.writeln(') {')
 	for defer_stmt in node.defer_stmts {
 		g.writeln('bool ${g.defer_flag_var(defer_stmt)} = false;')
+		for var in defer_stmt.defer_vars {
+			if var.name in fargs || var.kind == .constant {
+				continue
+			}
+			if var.info is ast.IdentVar {
+				info := var.info
+				if var.name !in g.defer_vars {
+					g.defer_vars << var.name
+					g.writeln('${g.typ(info.typ)} $var.name;')
+				}
+			}
+		}
 	}
 	if is_live_wrap {
 		// The live function just calls its implementation dual, while ensuring

vlib/v/parser/assign.v

@@ -6,7 +6,15 @@ module parser
 import v.ast
 
 fn (mut p Parser) assign_stmt() ast.Stmt {
+	mut defer_vars := p.defer_vars
+	p.defer_vars = []ast.Ident{}
+
 	exprs, comments := p.expr_list()
+
+	if !(p.inside_defer && p.tok.kind == .decl_assign) {
+		defer_vars << p.defer_vars
+	}
+	p.defer_vars = defer_vars
 	return p.partial_assign_stmt(exprs, comments)
 }
 

vlib/v/parser/if_match.v

@@ -106,7 +106,9 @@ fn (mut p Parser) if_expr(is_comptime bool) ast.IfExpr {
 			prev_guard = true
 		} else {
 			prev_guard = false
+			p.comp_if_cond = true
 			cond = p.expr(0)
+			p.comp_if_cond = false
 		}
 		comments << p.eat_comments({})
 		end_pos := p.prev_tok.position()

vlib/v/parser/parser.v

@@ -77,6 +77,9 @@ mut:
 	inside_asm_template bool
 	inside_asm          bool
 	global_labels       []string
+	inside_defer        bool
+	comp_if_cond        bool
+	defer_vars          []ast.Ident
 }
 
 // for tests
@@ -792,9 +795,13 @@ pub fn (mut p Parser) stmt(is_top_level bool) ast.Stmt {
 		.key_defer {
 			p.next()
 			spos := p.tok.position()
+			p.inside_defer = true
+			p.defer_vars = []ast.Ident{}
 			stmts := p.parse_block()
+			p.inside_defer = false
 			return ast.DeferStmt{
 				stmts: stmts
+				defer_vars: p.defer_vars.clone()
 				pos: spos.extend_with_last_line(p.tok.position(), p.prev_tok.line_nr)
 			}
 		}
@@ -1689,7 +1696,18 @@ fn (mut p Parser) parse_multi_expr(is_top_level bool) ast.Stmt {
 	// collect things upto hard boundaries
 	tok := p.tok
 	mut pos := tok.position()
+
+	mut defer_vars := p.defer_vars
+	p.defer_vars = []ast.Ident{}
+
 	left, left_comments := p.expr_list()
+
+	if !(p.inside_defer && p.tok.kind == .decl_assign) {
+		defer_vars << p.defer_vars
+	}
+
+	p.defer_vars = defer_vars
+
 	left0 := left[0]
 	if tok.kind == .key_mut && p.tok.kind != .decl_assign {
 		return p.error('expecting `:=` (e.g. `mut x :=`)')
@@ -1750,6 +1768,7 @@ pub fn (mut p Parser) parse_ident(language ast.Language) ast.Ident {
 			return ast.Ident{
 				tok_kind: p.tok.kind
 				name: '_'
+				comptime: p.comp_if_cond
 				kind: .blank_ident
 				pos: pos
 				info: ast.IdentVar{
@@ -1769,6 +1788,7 @@ pub fn (mut p Parser) parse_ident(language ast.Language) ast.Ident {
 			tok_kind: p.tok.kind
 			kind: .unresolved
 			name: name
+			comptime: p.comp_if_cond
 			language: language
 			mod: p.mod
 			pos: pos
@@ -1954,7 +1974,14 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 				} else if p.peek_tok.kind == .dot && p.peek_token(2).kind != .eof
 					&& p.peek_token(2).lit.len == 0 {
 					// incomplete module selector must be handled by dot_expr instead
-					node = p.parse_ident(language)
+					ident := p.parse_ident(language)
+					node = ident
+					if p.inside_defer {
+						if p.defer_vars.filter(it.name == ident.name
+							&& it.mod == ident.mod).len == 0 && ident.name != 'err' {
+							p.defer_vars << ident
+						}
+					}
 					return node
 				}
 			}
@@ -1975,7 +2002,14 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 	same_line := p.tok.line_nr == p.peek_tok.line_nr
 	// `(` must be on same line as name token otherwise it's a ParExpr
 	if !same_line && p.peek_tok.kind == .lpar {
-		node = p.parse_ident(language)
+		ident := p.parse_ident(language)
+		node = ident
+		if p.inside_defer {
+			if p.defer_vars.filter(it.name == ident.name && it.mod == ident.mod).len == 0
+				&& ident.name != 'err' {
+				p.defer_vars << ident
+			}
+		}
 	} else if p.peek_tok.kind == .lpar
 		|| (is_optional && p.peek_token(2).kind == .lpar) || p.is_generic_call() {
 		// foo(), foo<int>() or type() cast
@@ -2087,7 +2121,14 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 		// JS. function call with more than 1 dot
 		node = p.call_expr(language, mod)
 	} else {
-		node = p.parse_ident(language)
+		ident := p.parse_ident(language)
+		node = ident
+		if p.inside_defer {
+			if p.defer_vars.filter(it.name == ident.name && it.mod == ident.mod).len == 0
+				&& ident.name != 'err' {
+				p.defer_vars << ident
+			}
+		}
 	}
 	p.expr_mod = ''
 	return node

vlib/v/parser/pratt.v

@@ -33,7 +33,14 @@ pub fn (mut p Parser) check_expr(precedence int) ?ast.Expr {
 	// Prefix
 	match p.tok.kind {
 		.key_mut, .key_shared, .key_atomic, .key_static {
-			node = p.parse_ident(ast.Language.v)
+			ident := p.parse_ident(ast.Language.v)
+			node = ident
+			if p.inside_defer {
+				if p.defer_vars.filter(it.name == ident.name && it.mod == ident.mod).len == 0
+					&& ident.name != 'err' {
+					p.defer_vars << ident
+				}
+			}
 			p.is_stmt_ident = is_stmt_ident
 		}
 		.name, .question {

vlib/v/tests/defer_test.v

@@ -117,3 +117,28 @@ fn test_defer_order() {
 		assert i == 1
 	}
 }
+
+fn test_defer_access() {
+	if true {
+		mut i := 0
+		defer {
+			i++
+			assert i == 1
+		}
+	}
+}
+
+fn test_defer_arrays() {
+	mut ia := []int{}
+	defer {
+		ia << 1
+	}
+}
+
+fn test_defer_str_interpol() {
+	mut t := []string{}
+	defer {
+		t << 'test'
+		t << '${t[0]}'
+	}
+}