cgen, markused, checker: fix iteration over mutable option (fix #24860) (#25199)

vlib/v/ast/ast.v

@@ -1018,8 +1018,12 @@ pub mut:
 	stmts                 []Stmt   // all the statements in the source file
 	imports               []Import // all the imports
 	auto_imports          []string // imports that were implicitly added
+	used_imports          []string
+	implied_imports       []string                  // ​imports that the user's code uses but omitted to import explicitly, used by `vfmt`
 	embedded_files        []EmbeddedFile            // list of files to embed in the binary
 	imported_symbols      map[string]string         // used for `import {symbol}`, it maps symbol => module.symbol
+	imported_symbols_trie token.KeywordsMatcherTrie // constructed from imported_symbols, to accelerate presense checks
+	imported_symbols_used map[string]bool
 	errors                []errors.Error   // all the checker errors in the file
 	warnings              []errors.Warning // all the checker warnings in the file
 	notices               []errors.Notice  // all the checker notices in the file

vlib/v/checker/checker.v

@@ -4261,7 +4261,7 @@ fn (mut c Checker) ident(mut node ast.Ident) ast.Type {
 		}
 		mut name := node.name
 		// check for imported symbol
-		if name in c.file.imported_symbols {
+		if c.file.imported_symbols_trie.matches(name) {
 			name = c.file.imported_symbols[name]
 		}
 		// prepend mod to look for fn call or const

vlib/v/checker/for.v

@@ -254,6 +254,9 @@ fn (mut c Checker) for_in_stmt(mut node ast.ForInStmt) {
 			}
 			if node.val_is_mut {
 				value_type = value_type.ref()
+				if value_type.has_flag(.option) {
+					value_type = value_type.set_flag(.option_mut_param_t)
+				}
 				match mut node.cond {
 					ast.Ident {
 						if mut node.cond.obj is ast.Var {

vlib/v/fmt/comments.v

@@ -117,7 +117,7 @@ pub fn (mut f Fmt) import_comments(comments []ast.Comment, options CommentsOptio
 		return
 	}
 	if options.same_line {
-		f.remove_new_line(imports_buffer: true)
+		f.remove_new_line()
 	}
 	for c in comments {
 		ctext := c.text.trim_left('\x01')
@@ -129,7 +129,7 @@ pub fn (mut f Fmt) import_comments(comments []ast.Comment, options CommentsOptio
 			out_s += ' '
 		}
 		out_s += ctext
-		f.out_imports.writeln(out_s)
+		f.writeln(out_s)
 	}
 }
 

vlib/v/fmt/fmt.v

@@ -22,7 +22,6 @@ pub mut:
 	table              &ast.Table = unsafe { nil }
 	is_debug           bool
 	out                strings.Builder
-	out_imports        strings.Builder
 	indent             int
 	empty_line         bool
 	line_len           int    // the current line length, Note: it counts \t as 4 spaces, and starts at 0 after f.writeln
@@ -32,13 +31,12 @@ pub mut:
 	array_init_depth   int    // current level of hierarchy in array init
 	single_line_if     bool
 	cur_mod            string
-	did_imports        bool
+	import_pos         int               // position of the last import in the resulting string
-	import_pos         int               // position of the imports in the resulting string
-	auto_imports       map[string]bool   // potentially hidden imports(`sync` when using channels) and preludes(when embedding files)
-	used_imports       map[string]bool   // to remove unused imports
-	import_syms_used   map[string]bool   // to remove unused import symbols
 	mod2alias          map[string]string // for `import time as t`, will contain: 'time'=>'t'
 	mod2syms           map[string]string // import time { now } 'time.now'=>'now'
+	implied_import_str string            // ​imports that the user's code uses but omitted to import explicitly
+	processed_imports  []string
+	has_import_stmt    bool
 	use_short_fn_args  bool
 	single_line_fields bool // should struct fields be on a single line
 	in_lambda_depth    int
@@ -68,7 +66,6 @@ pub fn fmt(file ast.File, mut table ast.Table, pref_ &pref.Preferences, is_debug
 		pref:     pref_
 		is_debug: is_debug
 		out:      strings.new_builder(1000)
-		out_imports: strings.new_builder(200)
 	}
 	f.source_text = options.source_text
 	f.process_file_imports(file)
@@ -76,16 +73,15 @@ pub fn fmt(file ast.File, mut table ast.Table, pref_ &pref.Preferences, is_debug
 	f.indent--
 	f.stmts(file.stmts)
 	f.indent++
-	// Format after file import symbols are processed.
-	f.imports(f.file.imports)
 	res := f.out.str().trim_space() + '\n'
+
+	// `implied_imports` should append to end of `import` block
 	if res.len == 1 {
-		return f.out_imports.str().trim_space() + '\n'
+		return f.implied_import_str + '\n'
 	}
 	if res.len <= f.import_pos {
-		imp_str := f.out_imports.str().trim_space()
+		if f.implied_import_str.len > 0 {
-		if imp_str.len > 0 {
+			return res + '\n' + f.implied_import_str + '\n'
-			return res + '\n' + imp_str + '\n'
 		}
 		return res
 	}
@@ -98,7 +94,11 @@ pub fn fmt(file ast.File, mut table ast.Table, pref_ &pref.Preferences, is_debug
 			import_start_pos = stmt.pos.len
 		}
 	}
-	return res[..import_start_pos] + f.out_imports.str() + res[import_start_pos..]
+	if f.has_import_stmt || f.implied_import_str.len == 0 {
+		return res[..import_start_pos] + f.implied_import_str + res[import_start_pos..]
+	} else {
+		return res[..import_start_pos] + f.implied_import_str + '\n' + res[import_start_pos..]
+	}
 }
 
 /*
@@ -121,6 +121,12 @@ pub fn (f &Fmt) type_to_str(typ ast.Type) string {
 */
 
 pub fn (mut f Fmt) process_file_imports(file &ast.File) {
+	mut sb := strings.new_builder(128)
+	for imp in file.implied_imports {
+		sb.writeln('import ${imp}')
+	}
+	f.implied_import_str = sb.str()
+
 	for imp in file.imports {
 		f.mod2alias[imp.mod] = imp.alias
 		f.mod2alias[imp.mod.all_after('${file.mod.name}.')] = imp.alias
@@ -131,12 +137,8 @@ pub fn (mut f Fmt) process_file_imports(file &ast.File) {
 			f.mod2syms['${imp.mod}.${sym.name}'] = sym.name
 			f.mod2syms['${imp.mod.all_after_last('.')}.${sym.name}'] = sym.name
 			f.mod2syms[sym.name] = sym.name
-			f.import_syms_used[sym.name] = false
 		}
 	}
-	for mod in f.file.auto_imports {
-		f.auto_imports[mod] = true
-	}
 }
 
 //=== Basic buffer write operations ===//
@@ -186,15 +188,9 @@ pub fn (mut f Fmt) wrap_long_line(penalty_idx int, add_indent bool) bool {
 	return true
 }
 
-@[params]
-pub struct RemoveNewLineConfig {
-pub:
-	imports_buffer bool // Work on f.out_imports instead of f.out
-}
-
 // When the removal action actually occurs, the string of the last line after the removal is returned
-pub fn (mut f Fmt) remove_new_line(cfg RemoveNewLineConfig) string {
+pub fn (mut f Fmt) remove_new_line() string {
-	mut buffer := if cfg.imports_buffer { unsafe { &f.out_imports } } else { unsafe { &f.out } }
+	mut buffer := unsafe { &f.out }
 	mut i := 0
 	for i = buffer.len - 1; i >= 0; i-- {
 		if !buffer.byte_at(i).is_space() { // != `\n` {
@@ -314,76 +310,30 @@ pub fn (mut f Fmt) short_module(name string) string {
 
 //=== Import-related methods ===//
 
-pub fn (mut f Fmt) mark_types_import_as_used(typ ast.Type) {
+pub fn (mut f Fmt) import_stmt(imp ast.Import) {
-	sym := f.table.sym(typ)
+	f.has_import_stmt = true
-	match sym.info {
+	if imp.mod in f.file.auto_imports && imp.mod !in f.file.used_imports {
-		ast.Map {
-			map_info := sym.map_info()
-			f.mark_types_import_as_used(map_info.key_type)
-			f.mark_types_import_as_used(map_info.value_type)
-			return
-		}
-		ast.Array, ast.ArrayFixed {
-			f.mark_types_import_as_used(sym.info.elem_type)
-			return
-		}
-		ast.GenericInst {
-			for concrete_typ in sym.info.concrete_types {
-				f.mark_types_import_as_used(concrete_typ)
-			}
-		}
-		else {}
-	}
-	// `Type[T]` -> `Type` || `[]thread Type` -> `Type`.
-	name := sym.name.all_before('[').all_after(' ')
-	f.mark_import_as_used(name)
-}
-
-pub fn (mut f Fmt) mark_import_as_used(name string) {
-	parts := name.split('.')
-	sym := parts.last()
-	if sym in f.import_syms_used {
-		f.import_syms_used[sym] = true
-	}
-	if parts.len == 1 {
-		return
-	}
-	mod := parts[..parts.len - 1].join('.')
-	f.used_imports[mod] = true
-}
-
-pub fn (mut f Fmt) imports(imports []ast.Import) {
-	if f.did_imports || imports.len == 0 {
-		return
-	}
-	f.did_imports = true
-	mut processed_imports := map[string]bool{}
-	for imp in imports {
-		if imp.mod in f.auto_imports && imp.mod !in f.used_imports {
 		// Skip hidden imports like preludes.
-			continue
+		return
 	}
 	imp_stmt := f.imp_stmt_str(imp)
-		if imp_stmt in processed_imports {
+	if imp_stmt in f.processed_imports {
 		// Skip duplicates.
 		f.import_comments(imp.next_comments)
-			continue
+		return
 	}
-		processed_imports[imp_stmt] = true
+	f.processed_imports << imp_stmt
 	if !f.format_state.is_vfmt_on {
 		original_imp_line := f.get_source_lines()#[imp.pos.line_nr..imp.pos.last_line + 1].join('\n')
 		// Same line comments(`imp.comments`) are included in the `original_imp_line`.
-			f.out_imports.writeln(original_imp_line)
+		f.writeln(original_imp_line)
 		f.import_comments(imp.next_comments)
 	} else {
-			f.out_imports.writeln('import ${imp_stmt}')
+		f.writeln('import ${imp_stmt}')
 		f.import_comments(imp.comments, same_line: true)
 		f.import_comments(imp.next_comments)
 	}
-	}
+	f.import_pos = f.out.len
-	if processed_imports.len > 0 {
-		f.out_imports.writeln('')
-	}
 }
 
 pub fn (f &Fmt) imp_stmt_str(imp ast.Import) string {
@@ -391,7 +341,7 @@ pub fn (f &Fmt) imp_stmt_str(imp ast.Import) string {
 	// E.g.: `import foo { Foo }` || `import foo as f { Foo }`
 	has_alias := imp.alias != imp.source_name.all_after_last('.')
 	mut suffix := if has_alias { ' as ${imp.alias}' } else { '' }
-	mut syms := imp.syms.map(it.name).filter(f.import_syms_used[it])
+	mut syms := imp.syms.map(it.name).filter(f.file.imported_symbols_used[it])
 	syms.sort()
 	if syms.len > 0 {
 		suffix += if imp.syms[0].pos.line_nr == imp.pos.line_nr {
@@ -440,9 +390,9 @@ fn (f &Fmt) should_insert_newline_before_node(node ast.Node, prev_node ast.Node)
 					return true
 				}
 			}
-			// Imports are handled special hence they are ignored here
+			// Force a newline after imports
 			ast.Import {
-				return false
+				return node !is ast.Import
 			}
 			ast.ConstDecl {
 				if node !is ast.ConstDecl && !(node is ast.ExprStmt && node.expr is ast.Comment) {
@@ -572,9 +522,7 @@ pub fn (mut f Fmt) stmt(node ast.Stmt) {
 			f.hash_stmt(node)
 		}
 		ast.Import {
-			// Imports are handled after the file is formatted, to automatically add necessary modules
+			f.import_stmt(node)
-			// Just remember the position of the imports for now
-			f.import_pos = f.out.len
 		}
 		ast.InterfaceDecl {
 			f.interface_decl(node)
@@ -932,9 +880,6 @@ pub fn (mut f Fmt) comptime_for(node ast.ComptimeFor) {
 		(node.expr as ast.Ident).name
 	}
 	f.write('\$for ${node.val_var} in ${typ}.${node.kind.str()} {')
-	if node.typ != ast.void_type {
-		f.mark_types_import_as_used(node.typ)
-	}
 	if node.stmts.len > 0 || node.pos.line_nr < node.pos.last_line {
 		f.writeln('')
 		f.stmts(node.stmts)
@@ -1202,11 +1147,6 @@ fn (mut f Fmt) fn_body(node ast.FnDecl) {
 	} else {
 		f.writeln('')
 	}
-	// Mark all function's used type so that they are not removed from imports
-	for arg in node.params {
-		f.mark_types_import_as_used(arg.typ)
-	}
-	f.mark_types_import_as_used(node.return_type)
 }
 
 pub fn (mut f Fmt) for_c_stmt(node ast.ForCStmt) {
@@ -1355,7 +1295,6 @@ pub fn (mut f Fmt) global_decl(node ast.GlobalDecl) {
 		if node.is_block {
 			f.writeln('')
 		}
-		f.mark_types_import_as_used(field.typ)
 	}
 	f.comments_after_last_field(node.end_comments)
 	if node.is_block {
@@ -1568,7 +1507,6 @@ pub fn (mut f Fmt) interface_field(field ast.StructField, mut type_align FieldAl
 	if next_line_cmts.len > 0 {
 		f.comments(next_line_cmts, level: .indent)
 	}
-	f.mark_types_import_as_used(field.typ)
 }
 
 pub fn (mut f Fmt) interface_method(method ast.FnDecl, mut comment_align FieldAlign) {
@@ -1587,10 +1525,6 @@ pub fn (mut f Fmt) interface_method(method ast.FnDecl, mut comment_align FieldAl
 		f.writeln('')
 	}
 	f.comments(method.next_comments, level: .indent)
-	for param in method.params {
-		f.mark_types_import_as_used(param.typ)
-	}
-	f.mark_types_import_as_used(method.return_type)
 }
 
 pub fn (mut f Fmt) module_stmt(mod ast.Module) {
@@ -1655,7 +1589,6 @@ pub fn (mut f Fmt) sql_stmt_line(node ast.SqlStmtLine) {
 		table_name = f.no_cur_mod(f.short_module(sym.name)) // TODO: f.type_to_str?
 	}
 
-	f.mark_types_import_as_used(node.table_expr.typ)
 	f.write('\t')
 	match node.kind {
 		.insert {
@@ -1712,7 +1645,6 @@ pub fn (mut f Fmt) alias_type_decl(node ast.AliasTypeDecl) {
 			f.write('type ${node.name} = ')
 			f.struct_decl(ast.StructDecl{ fields: sym.info.fields }, true)
 			f.comments(node.comments, has_nl: false)
-			f.mark_types_import_as_used(node.parent_type)
 			return
 		}
 	}
@@ -1720,7 +1652,6 @@ pub fn (mut f Fmt) alias_type_decl(node ast.AliasTypeDecl) {
 	f.write('type ${node.name} = ${ptype}')
 
 	f.comments(node.comments, has_nl: false)
-	f.mark_types_import_as_used(node.parent_type)
 }
 
 pub fn (mut f Fmt) fn_type_decl(node ast.FnTypeDecl) {
@@ -1743,7 +1674,6 @@ pub fn (mut f Fmt) fn_type_decl(node ast.FnTypeDecl) {
 			f.write(arg.typ.share().str() + ' ')
 		}
 		f.write(arg.name)
-		f.mark_types_import_as_used(arg.typ)
 		mut s := f.no_cur_mod(f.table.type_to_str_using_aliases(arg.typ, f.mod2alias))
 		if arg.is_mut {
 			if s.starts_with('&') {
@@ -1769,7 +1699,6 @@ pub fn (mut f Fmt) fn_type_decl(node ast.FnTypeDecl) {
 	}
 	f.write(')')
 	if fn_info.return_type.idx() != ast.void_type_idx {
-		f.mark_types_import_as_used(fn_info.return_type)
 		ret_str := f.no_cur_mod(f.table.type_to_str_using_aliases(fn_info.return_type,
 			f.mod2alias))
 		f.write(' ${ret_str}')
@@ -1801,7 +1730,6 @@ pub fn (mut f Fmt) sum_type_decl(node ast.SumTypeDecl) {
 	mut variants := []Variant{cap: node.variants.len}
 	for i, variant in node.variants {
 		variants << Variant{f.table.type_to_str_using_aliases(variant.typ, f.mod2alias), i}
-		f.mark_types_import_as_used(variant.typ)
 	}
 	// The first variant is now used as the default variant when doing `a:= Sumtype{}`, i.e. a change in semantics.
 	// Sorting is disabled, because it is no longer a cosmetic change - it can change the default variant.
@@ -1851,7 +1779,6 @@ pub fn (mut f Fmt) array_init(node ast.ArrayInit) {
 	}
 	if node.exprs.len == 0 && node.typ != 0 && node.typ != ast.void_type {
 		// `x := []string{}`
-		f.mark_types_import_as_used(node.typ)
 		if node.alias_type != ast.void_type {
 			f.write(f.table.type_to_str_using_aliases(node.alias_type, f.mod2alias))
 		} else {
@@ -2054,7 +1981,6 @@ pub fn (mut f Fmt) array_init(node ast.ArrayInit) {
 }
 
 pub fn (mut f Fmt) as_cast(node ast.AsCast) {
-	f.mark_types_import_as_used(node.typ)
 	type_str := f.table.type_to_str_using_aliases(node.typ, f.mod2alias)
 	f.expr(node.expr)
 	f.write(' as ${type_str}')
@@ -2078,7 +2004,6 @@ pub fn (mut f Fmt) at_expr(node ast.AtExpr) {
 }
 
 fn (mut f Fmt) write_static_method(name string, short_name string) {
-	f.mark_import_as_used(name.split('__static__')[0])
 	if short_name.contains('.') {
 		indx := short_name.index('.') or { -1 } + 1
 		f.write(short_name[0..indx] + short_name[indx..].replace('__static__', '.').capitalize())
@@ -2094,20 +2019,6 @@ pub fn (mut f Fmt) call_expr(node ast.CallExpr) {
 			f.in_lambda_depth++
 			defer { f.in_lambda_depth-- }
 		}
-		if node.left is ast.Ident {
-			// `time.now()` without `time imported` is processed as a method call with `time` being
-			// a `node.left` expression. Import `time` automatically.
-			// TODO: fetch all available modules
-			if node.left.name in ['time', 'os', 'strings', 'math', 'json', 'base64']
-				&& !node.left.scope.known_var(node.left.name) {
-				f.file.imports << ast.Import{
-					source_name: node.left.name
-					mod:         node.left.name
-					alias:       node.left.name
-				}
-				f.used_imports[node.left.name] = true
-			}
-		}
 		f.expr(node.left)
 		is_method_newline = node.left.pos().last_line != node.name_pos.line_nr
 		if is_method_newline {
@@ -2126,7 +2037,6 @@ pub fn (mut f Fmt) call_expr(node ast.CallExpr) {
 			if node.is_static_method {
 				f.write_static_method(node.name, name)
 			} else {
-				f.mark_import_as_used(name)
 				f.write(name)
 			}
 		}
@@ -2164,7 +2074,6 @@ fn (mut f Fmt) write_generic_call_if_require(node ast.CallExpr) {
 				name = 'C.' + name
 			}
 			f.write(name)
-			f.mark_types_import_as_used(concrete_type)
 			if i != node.concrete_types.len - 1 {
 				f.write(', ')
 			}
@@ -2227,7 +2136,6 @@ pub fn (mut f Fmt) cast_expr(node ast.CastExpr) {
 		}
 	}
 	f.write('${typ}(')
-	f.mark_types_import_as_used(node.typ)
 	f.expr(node.expr)
 	if node.has_arg {
 		f.write(', ')
@@ -2370,7 +2278,6 @@ pub fn (mut f Fmt) dump_expr(node ast.DumpExpr) {
 pub fn (mut f Fmt) enum_val(node ast.EnumVal) {
 	name := f.short_module(node.enum_name)
 	f.write(name + '.' + node.val)
-	f.mark_import_as_used(name)
 }
 
 pub fn (mut f Fmt) ident(node ast.Ident) {
@@ -2414,7 +2321,6 @@ pub fn (mut f Fmt) ident(node ast.Ident) {
 		if node.name.contains('__static__') {
 			f.write_static_method(node.name, name)
 		} else {
-			f.mark_import_as_used(name)
 			f.write(name)
 		}
 		if node.concrete_types.len > 0 {
@@ -2433,7 +2339,6 @@ pub fn (mut f Fmt) ident(node ast.Ident) {
 		} else if node.or_expr.kind == .block {
 			f.or_expr(node.or_expr)
 		}
-		f.mark_import_as_used(name)
 	}
 }
 
@@ -2791,10 +2696,6 @@ pub fn (mut f Fmt) lock_expr(node ast.LockExpr) {
 pub fn (mut f Fmt) map_init(node ast.MapInit) {
 	if node.keys.len == 0 && !node.has_update_expr {
 		if node.typ > ast.void_type {
-			sym := f.table.sym(node.typ)
-			info := sym.info as ast.Map
-			f.mark_types_import_as_used(info.key_type)
-			f.mark_types_import_as_used(info.value_type)
 			f.write(f.table.type_to_str_using_aliases(node.typ, f.mod2alias))
 		}
 		if node.pos.line_nr == node.pos.last_line {
@@ -2929,7 +2830,6 @@ pub fn (mut f Fmt) match_expr(node ast.MatchExpr) {
 
 pub fn (mut f Fmt) offset_of(node ast.OffsetOf) {
 	f.write('__offsetof(${f.table.type_to_str_using_aliases(node.struct_type, f.mod2alias)}, ${node.field})')
-	f.mark_types_import_as_used(node.struct_type)
 }
 
 pub fn (mut f Fmt) or_expr(node ast.OrExpr) {
@@ -3272,7 +3172,6 @@ pub fn (mut f Fmt) string_inter_literal(node ast.StringInterLiteral) {
 
 pub fn (mut f Fmt) type_expr(node ast.TypeNode) {
 	if node.stmt == ast.empty_stmt {
-		f.mark_types_import_as_used(node.typ)
 		f.write(f.table.type_to_str_using_aliases(node.typ, f.mod2alias))
 	} else {
 		f.struct_decl(ast.StructDecl{ fields: (node.stmt as ast.StructDecl).fields },

vlib/v/fmt/struct.v

@@ -41,7 +41,6 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl, is_anon bool) {
 			if i < node.implements_types.len - 1 {
 				f.write(', ')
 			}
-			f.mark_types_import_as_used(t.typ)
 		}
 	}
 	// Calculate the alignments first
@@ -52,7 +51,6 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl, is_anon bool) {
 		f.comments_before_field(node.pre_comments)
 	}
 	for embed in node.embeds {
-		f.mark_types_import_as_used(embed.typ)
 		styp := f.table.type_to_str_using_aliases(embed.typ, f.mod2alias)
 
 		pre_comments := embed.comments.filter(it.pos.pos < embed.pos.pos)
@@ -101,7 +99,6 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl, is_anon bool) {
 		if !f.write_anon_struct_field_decl(field.typ, field.anon_struct_decl) {
 			f.write(field_types[i])
 		}
-		f.mark_types_import_as_used(field.typ)
 		attrs_len := inline_attrs_len(field.attrs)
 		if field.has_default_expr {
 			f.write(' '.repeat(default_expr_align.max_len(field.pos.line_nr) - field_types[i].len))
@@ -202,7 +199,6 @@ pub fn (mut f Fmt) struct_init(node ast.StructInit) {
 	defer {
 		f.is_struct_init = struct_init_save
 	}
-	f.mark_types_import_as_used(node.typ)
 	sym_name := f.table.sym(node.typ).name
 	// f.write('<old name: $type_sym.name>')
 	mut name := if !sym_name.starts_with('C.') && !sym_name.starts_with('JS.') {
@@ -228,11 +224,9 @@ pub fn (mut f Fmt) struct_init(node ast.StructInit) {
 			f.comments(node.pre_comments, same_line: true, has_nl: true, level: .indent)
 			f.write('}')
 		}
-		f.mark_import_as_used(name)
 	} else if node.no_keys {
 		// `Foo{1,2,3}` (short syntax, no keys)
 		f.write('${name}{')
-		f.mark_import_as_used(name)
 		if node.has_update_expr {
 			f.write('...')
 			f.expr(node.update_expr)
@@ -255,7 +249,6 @@ pub fn (mut f Fmt) struct_init(node ast.StructInit) {
 		}
 		if !use_short_args || node.is_anon {
 			f.write('${name}{')
-			f.mark_import_as_used(name)
 			if single_line_fields {
 				f.write(' ')
 			}

vlib/v/fmt/tests/import_selective_with_func_call_args_keep.vv

@@ -0,0 +1,8 @@
+module main
+
+import term { bright_cyan, colorize }
+
+fn main() {
+	n := colorize(bright_cyan, 'hello')
+	println(n)
+}

vlib/v/gen/c/assign.v

@@ -866,9 +866,19 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 							g.write('*')
 						}
 						if node_.op == .assign && var_type.has_flag(.option_mut_param_t) {
+							if val is ast.CastExpr {
+								g.expr(left)
+								g.write('->state = ')
+								g.expr(val)
+								g.writeln('.state;')
+							}
 							g.write('memcpy(&')
 							g.expr(left)
+							if val is ast.CastExpr {
+								g.write('->data, ')
+							} else {
 								g.write('->data, *(${g.styp(val_type)}**)&')
+							}
 						} else if var_type.has_flag(.option_mut_param_t) {
 							g.expr(left)
 							g.write(' = ')

vlib/v/gen/c/autofree.v

@@ -62,7 +62,7 @@ fn (mut g Gen) autofree_scope_vars2(scope &ast.Scope, start_pos int, end_pos int
 		match obj {
 			ast.Var {
 				g.trace_autofree('// var "${obj.name}" var.pos=${obj.pos.pos} var.line_nr=${obj.pos.line_nr}')
-				if obj.name == g.returned_var_name {
+				if obj.name in g.returned_var_names {
 					g.print_autofree_var(obj, 'returned from function')
 					g.trace_autofree('// skipping returned var')
 					continue
@@ -247,3 +247,17 @@ fn (mut g Gen) autofree_var_call(free_fn_name string, v ast.Var) {
 	}
 	g.autofree_scope_stmts << af.str()
 }
+
+fn (mut g Gen) detect_used_var_on_return(expr ast.Expr) {
+	match expr {
+		ast.Ident {
+			g.returned_var_names[expr.name] = true
+		}
+		ast.StructInit {
+			for field_expr in expr.init_fields {
+				g.detect_used_var_on_return(field_expr.expr)
+			}
+		}
+		else {}
+	}
+}

vlib/v/gen/c/cgen.v

@@ -233,7 +233,7 @@ mut:
 	aggregate_type_idx  int
 	arg_no_auto_deref   bool            // smartcast must not be dereferenced
 	branch_parent_pos   int             // used in BranchStmt (continue/break) for autofree stop position
-	returned_var_name   string   // to detect that a var doesn't need to be freed since it's being returned
+	returned_var_names  map[string]bool // to detect that vars doesn't need to be freed since it's being returned
 	infix_left_var_name string          // a && if expr
 	curr_var_name       []string        // curr var name on assignment
 	called_fn_name      string
@@ -6241,6 +6241,9 @@ fn (mut g Gen) return_stmt(node ast.Return) {
 				g.writeln(' }, (${option_name}*)(&${tmpvar}), sizeof(${styp}));')
 			}
 			g.write_defer_stmts_when_needed()
+			if g.is_autofree {
+				g.detect_used_var_on_return(expr0)
+			}
 			g.autofree_scope_vars(node.pos.pos - 1, node.pos.line_nr, true)
 			g.writeln('return ${tmpvar};')
 			return
@@ -6286,6 +6289,9 @@ fn (mut g Gen) return_stmt(node ast.Return) {
 				g.writeln(' }, (${result_name}*)(&${tmpvar}), sizeof(${styp}));')
 			}
 			g.write_defer_stmts_when_needed()
+			if g.is_autofree {
+				g.detect_used_var_on_return(expr0)
+			}
 			g.autofree_scope_vars(node.pos.pos - 1, node.pos.line_nr, true)
 			g.writeln('return ${tmpvar};')
 			return
@@ -6294,9 +6300,7 @@ fn (mut g Gen) return_stmt(node ast.Return) {
 		// set free_parent_scopes to true, since all variables defined in parent
 		// scopes need to be freed before the return
 		if g.is_autofree {
-			if expr0 is ast.Ident {
+			g.detect_used_var_on_return(expr0)
-				g.returned_var_name = expr0.name
-			}
 			if !use_tmp_var && !g.is_builtin_mod {
 				use_tmp_var = expr0 is ast.CallExpr
 			}

vlib/v/gen/c/fn.v

@@ -196,7 +196,7 @@ fn (mut g Gen) gen_fn_decl(node &ast.FnDecl, skip bool) {
 	}
 	*/
 
-	g.returned_var_name = ''
+	g.returned_var_names.clear()
 	old_g_autofree := g.is_autofree
 	if node.is_manualfree {
 		g.is_autofree = false

vlib/v/gen/c/testdata/autofree_toml.c.must_have

@@ -0,0 +1,9 @@
+_result_toml__scanner__Scanner_ptr toml__scanner__new_scanner(toml__scanner__Config config) {
+	_result_toml__scanner__Scanner_ptr _t3 = {0};
+	_result_ok(&(toml__scanner__Scanner*[]) { s }, (_result*)(&_t3), sizeof(toml__scanner__Scanner*));
+	return _t3;
+}
+toml__ast__Quoted toml__parser__Parser_quoted(toml__parser__Parser* p) {
+	return ((toml__ast__Quoted){.text =  string_clone_static(lit),.pos = toml__token__Token_pos(&p->tok),.is_multiline = is_multiline,.quote = quote,});
+}
+

vlib/v/gen/c/testdata/autofree_toml.vv

@@ -0,0 +1,15 @@
+// vtest vflags: -autofree
+import toml
+import os
+
+fn main() {
+	config_fname := 'config.toml'
+	tab_title := 'test tab title'
+	if !os.exists(config_fname) {
+		mut f := os.create(config_fname) or { panic(err) }
+		f.writeln('tab_title = "${tab_title}"') or { panic(err) }
+		f.close()
+	}
+	doc := toml.parse_file(config_fname) or { panic(err) }
+	assert doc.value('tab_title').string() == tab_title
+}

vlib/v/markused/walker.v

@@ -1300,6 +1300,10 @@ fn (mut w Walker) mark_resource_dependencies() {
 		w.fn_by_name(builderptr_idx + '.write_string')
 		w.fn_by_name('strings.new_builder')
 		w.uses_free[ast.string_type] = true
+
+		if w.table.dumps.keys().any(ast.Type(u32(it)).has_flag(.option)) {
+			w.fn_by_name('str_intp')
+		}
 	}
 	if w.features.auto_str_ptr {
 		w.fn_by_name('isnil')

vlib/v/parser/enum.v

@@ -61,7 +61,7 @@ fn (mut p Parser) enum_decl() ast.EnumDecl {
 			end_pos)
 		return ast.EnumDecl{}
 	}
-	if enum_name in p.imported_symbols {
+	if p.is_imported_symbol(enum_name) {
 		p.error_with_pos('cannot register enum `${enum_name}`, this type was already imported',
 			end_pos)
 		return ast.EnumDecl{}

vlib/v/parser/fn.v

@@ -89,10 +89,13 @@ fn (mut p Parser) call_expr(language ast.Language, mod string) ast.CallExpr {
 		}
 		or_kind = if is_not { .propagate_result } else { .propagate_option }
 	}
-	if fn_name in p.imported_symbols {
+	if p.is_imported_symbol(fn_name) {
+		check := !p.imported_symbols_used[fn_name]
 		fn_name = p.imported_symbols[fn_name]
+		if check {
 			p.register_used_import_for_symbol_name(fn_name)
 		}
+	}
 	comments := p.eat_comments(same_line: true)
 	pos.update_last_line(p.prev_tok.line_nr)
 	return ast.CallExpr{
@@ -148,6 +151,13 @@ fn (mut p Parser) call_args() []ast.CallArg {
 			expr = p.struct_init('void_type', .short_syntax, false)
 		} else {
 			expr = p.expr(0)
+			if mut expr is ast.Ident {
+				if p.is_imported_symbol(expr.name) && !p.imported_symbols_used[expr.name] {
+					// func call arg is another function call
+					// import term { bright_cyan, colorize } ... colorize(bright_cyan, 'hello')
+					p.register_used_import_for_symbol_name(p.imported_symbols[expr.name])
+				}
+			}
 		}
 		if array_decompose {
 			expr = ast.ArrayDecompose{
@@ -383,7 +393,7 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 			}
 		}
 		if !p.pref.is_fmt {
-			if name in p.imported_symbols {
+			if p.is_imported_symbol(name) {
 				p.error_with_pos('cannot redefine imported function `${name}`', name_pos)
 				return ast.FnDecl{
 					scope: unsafe { nil }

vlib/v/parser/module.v

@@ -35,6 +35,10 @@ fn (mut p Parser) register_used_import(alias string) {
 
 fn (mut p Parser) register_used_import_for_symbol_name(sym_name string) {
 	short_import_name := sym_name.all_before_last('.').all_after_last('.')
+	short_symbol_name := sym_name.all_after_last('.')
+	if p.is_imported_symbol(short_symbol_name) {
+		p.imported_symbols_used[short_symbol_name] = true
+	}
 	for alias, mod in p.imports {
 		if mod == short_import_name {
 			p.register_used_import(alias)
@@ -62,7 +66,14 @@ fn (mut p Parser) register_auto_import(alias string) {
 	if alias !in p.auto_imports {
 		p.auto_imports << alias
 	}
-	p.register_used_import(alias)
+	// do not call `register_used_import()` here as it may not used by the code.
+	// for example, when using `chan`, but we has no `sync.xx()` call in the code.
+}
+
+fn (mut p Parser) register_implied_import(alias string) {
+	if alias !in p.implied_imports {
+		p.implied_imports << alias
+	}
 }
 
 fn (mut p Parser) check_unused_imports() {
@@ -75,7 +86,8 @@ fn (mut p Parser) check_unused_imports() {
 	for import_m in p.ast_imports {
 		alias := import_m.alias
 		mod := import_m.mod
-		if !(alias.len == 1 && alias[0] == `_`) && !p.is_used_import(alias) {
+		if !(alias.len == 1 && alias[0] == `_`) && !p.is_used_import(alias)
+			&& alias !in p.auto_imports {
 			mod_alias := if alias == mod { alias } else { '${alias} (${mod})' }
 			p.warn_with_pos("module '${mod_alias}' is imported but never used", import_m.mod_pos)
 		}
@@ -310,12 +322,13 @@ fn (mut p Parser) import_syms(mut parent ast.Import) {
 	for p.tok.kind == .name {
 		pos := p.tok.pos()
 		alias := p.check_name()
-		if alias in p.imported_symbols {
+		if p.is_imported_symbol(alias) {
 			p.error_with_pos('cannot register symbol `${alias}`, it was already imported',
 				pos)
 			return
 		}
 		p.imported_symbols[alias] = parent.mod + '.' + alias
+		p.rebuild_imported_symbols_matcher(alias)
 		// so we can work with this in fmt+checker
 		parent.syms << ast.ImportSymbol{
 			pos:  pos
@@ -335,3 +348,12 @@ fn (mut p Parser) import_syms(mut parent ast.Import) {
 	}
 	p.next()
 }
+
+fn (mut p Parser) rebuild_imported_symbols_matcher(name string) {
+	p.imported_symbols_trie = token.new_keywords_matcher_from_array_trie(p.imported_symbols.keys())
+}
+
+@[inline]
+fn (mut p Parser) is_imported_symbol(name string) bool {
+	return p.imported_symbols_trie.matches(name)
+}

vlib/v/parser/parse_type.v

@@ -636,9 +636,12 @@ fn (mut p Parser) parse_any_type(language ast.Language, is_ptr bool, check_dot b
 	} else if p.expr_mod != '' && !p.inside_generic_params {
 		// p.expr_mod is from the struct and not from the generic parameter
 		name = p.expr_mod + '.' + name
-	} else if name in p.imported_symbols {
+	} else if p.is_imported_symbol(name) {
+		check := !p.imported_symbols_used[name]
 		name = p.imported_symbols[name]
+		if check {
 			p.register_used_import_for_symbol_name(name)
+		}
 	} else if !p.builtin_mod && name.len > 1 && name !in p.table.type_idxs {
 		// `Foo` in module `mod` means `mod.Foo`
 		name = p.mod + '.' + name

vlib/v/parser/parser.v

@@ -81,9 +81,12 @@ mut:
 	last_enum_mod            string            // saves the last enum mod name on an array initialization
 	imports                  map[string]string // alias => mod_name
 	ast_imports              []ast.Import      // mod_names
-	used_imports             []string          // alias
+	used_imports             []string
 	auto_imports             []string // imports, the user does not need to specify
+	implied_imports          []string // ​imports that the user's code uses but omitted to import explicitly, used by `vfmt`
 	imported_symbols         map[string]string
+	imported_symbols_used    map[string]bool
+	imported_symbols_trie    token.KeywordsMatcherTrie
 	is_amp                   bool // for generating the right code for `&Foo{}`
 	returns                  bool
 	is_stmt_ident            bool // true while the beginning of a statement is an ident/selector
@@ -341,7 +344,11 @@ pub fn (mut p Parser) parse() &ast.File {
 		mod:                   module_decl
 		imports:               p.ast_imports
 		imported_symbols:      p.imported_symbols
+		imported_symbols_trie: token.new_keywords_matcher_from_array_trie(p.imported_symbols.keys())
+		imported_symbols_used: p.imported_symbols_used
 		auto_imports:          p.auto_imports
+		used_imports:          p.used_imports
+		implied_imports:       p.implied_imports
 		stmts:                 stmts
 		scope:                 p.scope
 		global_scope:          p.table.global_scope
@@ -587,7 +594,7 @@ fn (mut p Parser) check_name() string {
 	name := p.tok.lit
 	if p.tok.kind != .name && p.peek_tok.kind == .dot && name in p.imports {
 		p.register_used_import(name)
-	} else if p.tok.kind == .name && p.peek_tok.kind == .dot && name in p.imported_symbols {
+	} else if p.tok.kind == .name && p.is_imported_symbol(name) && !p.imported_symbols_used[name] {
 		// symbols like Enum.field_name
 		p.register_used_import_for_symbol_name(p.imported_symbols[name])
 	}
@@ -2085,6 +2092,17 @@ fn (mut p Parser) dot_expr(left ast.Expr) ast.Expr {
 		if mut left_node is ast.CallExpr {
 			left_node.is_return_used = true
 		}
+		if p.pref.is_fmt {
+			if mut left_node is ast.Ident {
+				// `time.now()` without `time imported` is processed as a method call with `time` being
+				// a `left_node` expression. Import `time` automatically.
+				// TODO: fetch all available modules
+				if left_node.name in ['time', 'os', 'strings', 'math', 'json', 'base64']
+					&& !left_node.scope.known_var(left_node.name) {
+					p.register_implied_import(left_node.name)
+				}
+			}
+		}
 		mcall_expr := ast.CallExpr{
 			left:              left
 			name:              field_name
@@ -2681,7 +2699,7 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 			return ast.FnTypeDecl{}
 		}
 	}
-	if name in p.imported_symbols {
+	if p.is_imported_symbol(name) {
 		p.error_with_pos('cannot register alias `${name}`, this type was already imported',
 			end_pos)
 		return ast.AliasTypeDecl{}

vlib/v/parser/struct.v

@@ -73,7 +73,7 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 		p.error_with_pos('struct names must have more than one character', name_pos)
 		return ast.StructDecl{}
 	}
-	if name in p.imported_symbols {
+	if p.is_imported_symbol(name) {
 		p.error_with_pos('cannot register struct `${name}`, this type was already imported',
 			name_pos)
 		return ast.StructDecl{}
@@ -651,7 +651,7 @@ fn (mut p Parser) interface_decl() ast.InterfaceDecl {
 	mut pre_comments := p.eat_comments()
 	p.check(.lcbr)
 	pre_comments << p.eat_comments()
-	if modless_name in p.imported_symbols {
+	if p.is_imported_symbol(modless_name) {
 		p.error_with_pos('cannot register interface `${interface_name}`, this type was already imported',
 			name_pos)
 		return ast.InterfaceDecl{}

vlib/v/slow_tests/valgrind/1.strings_and_arrays.v

@@ -398,6 +398,7 @@ fn advanced_options() {
 	s2 := parse_header1('foo:bar') or { return }
 	_ := s.len + s2.len // avoid warning for unused variables
 	// TODO: fix -autofree, so that it adds this free automatically:
+	unsafe { s.free() }
 	unsafe { s2.free() }
 }
 

vlib/v/tests/options/option_for_mut_test.v

@@ -0,0 +1,15 @@
+module main
+
+fn test_main() {
+	mut data := [3]?int{}
+
+	for mut d in data {
+		d = ?int(1)
+		assert '${d}' == 'Option(1)'
+	}
+
+	for i in 0 .. data.len {
+		data[i] = ?int(3)
+	}
+	assert '${data}' == '[Option(3), Option(3), Option(3)]'
+}

vlib/v/token/keywords_matcher_trie.v

@@ -11,6 +11,11 @@ pub mut:
 	max_len int
 }
 
+// str returns a short representation of matcher
+pub fn (km &KeywordsMatcherTrie) str() string {
+	return 'KeywordsMatcherTrie{ /* nodes.len: ${km.nodes.len} */ min_len: ${km.min_len}, max_len: ${km.max_len} }'
+}
+
 // TrieNode is a single node from a trie, used by KeywordsMatcherTrie
 pub struct TrieNode {
 pub mut:
@@ -18,6 +23,14 @@ pub mut:
 	value    int = -1 // when != -1, it is a leaf node representing a match
 }
 
+// str returns a string representation of the node content
+pub fn (node &TrieNode) str() string {
+	if isnil(node) {
+		return '&TrieNode(nil)'
+	}
+	return '&TrieNode{value: ${node.value}}'
+}
+
 // find tries to find the given `word` in the set of all previously added words
 // to the KeywordsMatcherTrie instance. It returns -1 if the word was NOT found
 // there at all. If the word was found, find will return the `value` (value => 0),