| 1 | // Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved. |
| 2 | // Use of this source code is governed by an MIT license that can be found in the LICENSE file. |
| 3 | module checker |
| 4 | |
| 5 | import v.ast |
| 6 | |
| 7 | // error_type_name returns a proper type name reference for error messages |
| 8 | // ? => Option type |
| 9 | // ! => Result type |
| 10 | // others => type `name` |
| 11 | fn (mut c Checker) error_type_name(exp_type ast.Type) string { |
| 12 | return if exp_type == ast.void_type.set_flag(.result) { |
| 13 | 'Result type' |
| 14 | } else if exp_type == ast.void_type.set_flag(.option) { |
| 15 | 'Option type' |
| 16 | } else { |
| 17 | 'type `${c.table.type_to_str(exp_type)}`' |
| 18 | } |
| 19 | } |
| 20 | |
| 21 | @[inline] |
| 22 | fn (mut c Checker) error_unaliased_type_name(exp_type ast.Type) string { |
| 23 | return c.error_type_name(c.table.unaliased_type(exp_type)) |
| 24 | } |
| 25 | |
| 26 | // returns_call_like_result_expr reports whether `expr` is a `CallExpr`, |
| 27 | // possibly wrapped in redundant `ParExpr`s. Used to decide whether the |
| 28 | // return path is shaped like `return foo()` / `return (foo())` — the |
| 29 | // shapes for which cgen can emit a `_result_*` alias clone. |
| 30 | fn returns_call_like_result_expr(expr ast.Expr) bool { |
| 31 | mut e := expr |
| 32 | for e is ast.ParExpr { |
| 33 | e = e.expr |
| 34 | } |
| 35 | return e is ast.CallExpr |
| 36 | } |
| 37 | |
| 38 | // TODO: non deferred |
| 39 | fn (mut c Checker) return_stmt(mut node ast.Return) { |
| 40 | if c.table.cur_fn == unsafe { nil } { |
| 41 | return |
| 42 | } |
| 43 | prev_inside_return := c.inside_return |
| 44 | c.inside_return = true |
| 45 | defer { |
| 46 | c.inside_return = prev_inside_return |
| 47 | } |
| 48 | |
| 49 | // check `defer_stmts` in return, to ensure the same behavior with `cgen` |
| 50 | old_inside_defer := c.inside_defer |
| 51 | c.inside_defer = true |
| 52 | for i := c.table.cur_fn.defer_stmts.len - 1; i >= 0; i-- { |
| 53 | c.stmts(mut c.table.cur_fn.defer_stmts[i].stmts) |
| 54 | } |
| 55 | c.inside_defer = old_inside_defer |
| 56 | |
| 57 | c.expected_type = c.table.cur_fn.return_type |
| 58 | mut expected_type := c.unwrap_generic(c.expected_type) |
| 59 | if expected_type != 0 && c.table.sym(expected_type).kind == .alias { |
| 60 | unaliased_type := c.table.unaliased_type(expected_type) |
| 61 | if unaliased_type.has_option_or_result() { |
| 62 | expected_type = unaliased_type |
| 63 | } |
| 64 | } |
| 65 | expected_type_sym := c.table.sym(expected_type) |
| 66 | if expected_type_sym.info is ast.ArrayFixed { |
| 67 | c.table.find_or_register_array_fixed(expected_type_sym.info.elem_type, |
| 68 | expected_type_sym.info.size, expected_type_sym.info.size_expr, true) |
| 69 | } |
| 70 | if node.exprs.len > 0 && c.table.cur_fn.return_type == ast.void_type { |
| 71 | c.error('unexpected argument, current function does not return anything', |
| 72 | node.exprs[0].pos()) |
| 73 | return |
| 74 | } else if node.exprs.len > 1 && c.table.cur_fn.return_type == ast.void_type.set_flag(.option) { |
| 75 | c.error('can only return `none` from an Option-only return function', node.exprs[0].pos()) |
| 76 | return |
| 77 | } else if node.exprs.len > 1 && c.table.cur_fn.return_type == ast.void_type.set_flag(.result) { |
| 78 | c.error('functions with Result-only return types can only return an error', |
| 79 | node.exprs[0].pos()) |
| 80 | return |
| 81 | } else if node.exprs.len == 0 && !(c.expected_type == ast.void_type |
| 82 | || expected_type_sym.kind == .void) { |
| 83 | stype := c.table.type_to_str(expected_type) |
| 84 | arg := if expected_type_sym.kind == .multi_return { 'arguments' } else { 'argument' } |
| 85 | c.error('expected `${stype}` ${arg}', node.pos) |
| 86 | return |
| 87 | } |
| 88 | if node.exprs.len == 0 { |
| 89 | return |
| 90 | } |
| 91 | exp_is_option := expected_type.has_flag(.option) |
| 92 | exp_is_result := expected_type.has_flag(.result) |
| 93 | mut expected_types := [expected_type] |
| 94 | if expected_type_sym.info is ast.MultiReturn { |
| 95 | expected_types = expected_type_sym.info.types.clone() |
| 96 | if c.table.cur_concrete_types.len > 0 { |
| 97 | expected_types = expected_types.map(c.unwrap_generic(it)) |
| 98 | c.table.used_features.comptime_syms[c.table.find_or_register_multi_return(expected_types)] = true |
| 99 | } |
| 100 | } |
| 101 | mut got_types := []ast.Type{} |
| 102 | mut expr_idxs := []int{} |
| 103 | for i, mut expr in node.exprs { |
| 104 | mut typ := c.expr(mut expr) |
| 105 | if typ == 0 { |
| 106 | return |
| 107 | } |
| 108 | // Handle `return unsafe { none }` |
| 109 | if mut expr is ast.UnsafeExpr && expr.expr is ast.None { |
| 110 | c.error('cannot return `none` in unsafe block', expr.expr.pos) |
| 111 | } |
| 112 | if typ == ast.void_type { |
| 113 | c.error('`${expr}` used as value', node.pos) |
| 114 | return |
| 115 | } |
| 116 | // Unpack multi return types |
| 117 | sym := c.table.sym(typ) |
| 118 | if sym.kind == .multi_return { |
| 119 | if i > 0 || i != node.exprs.len - 1 { |
| 120 | c.error('cannot use multi-return with other return types', expr.pos()) |
| 121 | } |
| 122 | for t in sym.mr_info().types { |
| 123 | got_types << t |
| 124 | expr_idxs << i |
| 125 | } |
| 126 | } else { |
| 127 | if mut expr is ast.Ident && expr.obj is ast.Var { |
| 128 | if expr.obj.smartcasts.len > 0 { |
| 129 | typ = c.unwrap_generic(c.visible_var_type_for_read(expr.obj)) |
| 130 | } |
| 131 | if expr.obj.ct_type_var != .no_comptime { |
| 132 | typ = c.type_resolver.get_type_or_default(expr, typ) |
| 133 | } |
| 134 | if expr.obj.expr is ast.IfGuardExpr { |
| 135 | if var := expr.scope.find_var(expr.name) { |
| 136 | typ = var.typ |
| 137 | } |
| 138 | } |
| 139 | } else if mut expr is ast.SelectorExpr { |
| 140 | if expr.expr_type != 0 { |
| 141 | scope_field := expr.scope.find_struct_field(smartcast_selector_expr_str(expr), |
| 142 | expr.expr_type, expr.field_name) |
| 143 | if scope_field != unsafe { nil } && scope_field.smartcasts.len > 0 { |
| 144 | typ = c.unwrap_generic(c.exposed_smartcast_type(scope_field.orig_type, |
| 145 | scope_field.smartcasts.last(), scope_field.is_mut)) |
| 146 | } |
| 147 | } |
| 148 | } |
| 149 | got_types << typ |
| 150 | expr_idxs << i |
| 151 | } |
| 152 | } |
| 153 | node.types = got_types |
| 154 | $if debug_manualfree ? { |
| 155 | cfn := c.table.cur_fn |
| 156 | if cfn.is_manualfree { |
| 157 | pnames := cfn.params.map(it.name) |
| 158 | for expr in node.exprs { |
| 159 | if expr is ast.Ident { |
| 160 | if expr.name in pnames { |
| 161 | c.note('returning a parameter in a fn marked with `@[manualfree]` can cause double freeing in the caller', |
| 162 | node.pos) |
| 163 | } |
| 164 | } |
| 165 | } |
| 166 | } |
| 167 | } |
| 168 | // allow `none` & `error` return types for function that returns option |
| 169 | option_type_idx := c.table.type_idxs['_option'] |
| 170 | result_type_idx := c.table.type_idxs['_result'] |
| 171 | got_types_0_idx := got_types[0].idx() |
| 172 | if exp_is_option && got_types_0_idx == ast.error_type_idx { |
| 173 | c.error('Option and Result types have been split, use `!Foo` to return errors', node.pos) |
| 174 | } else if exp_is_result && got_types_0_idx == ast.none_type_idx { |
| 175 | c.error('Option and Result types have been split, use `?` to return none', node.pos) |
| 176 | } |
| 177 | expected_fn_return_type_has_option := c.table.cur_fn.return_type.has_flag(.option) |
| 178 | expected_fn_return_type_has_result := c.table.cur_fn.return_type.has_flag(.result) |
| 179 | if exp_is_option && expected_fn_return_type_has_result { |
| 180 | if got_types_0_idx == ast.none_type_idx { |
| 181 | c.error('cannot use `none` as ${c.error_type_name(c.table.unaliased_type(c.table.cur_fn.return_type))} in return argument', |
| 182 | node.pos) |
| 183 | return |
| 184 | } |
| 185 | return |
| 186 | } |
| 187 | if exp_is_result && expected_fn_return_type_has_option { |
| 188 | c.error('expecting to return a ?Type, but you are returning ${c.error_type_name(expected_type)} instead', |
| 189 | node.pos) |
| 190 | return |
| 191 | } |
| 192 | if (exp_is_option |
| 193 | && got_types_0_idx in [ast.none_type_idx, ast.error_type_idx, option_type_idx]) |
| 194 | || (exp_is_result && got_types_0_idx in [ast.error_type_idx, result_type_idx]) { |
| 195 | return |
| 196 | } |
| 197 | if expected_types.len > 0 && expected_types.len != got_types.len { |
| 198 | // `fn foo() !(int, string) { return Err{} }` |
| 199 | if (exp_is_option || exp_is_result) && node.exprs.len == 1 { |
| 200 | mut expr_ := node.exprs[0] |
| 201 | got_type := c.expr(mut expr_) |
| 202 | got_type_sym := c.table.sym(got_type) |
| 203 | if got_type_sym.kind == .struct && c.type_implements(got_type, ast.error_type, node.pos) { |
| 204 | node.exprs[0] = ast.CastExpr{ |
| 205 | expr: node.exprs[0] |
| 206 | typname: 'IError' |
| 207 | typ: ast.error_type |
| 208 | expr_type: got_type |
| 209 | pos: node.pos |
| 210 | } |
| 211 | node.types[0] = ast.error_type |
| 212 | return |
| 213 | } |
| 214 | } |
| 215 | arg := if expected_types.len == 1 { 'argument' } else { 'arguments' } |
| 216 | midx := int_max(0, int_min(expected_types.len, expr_idxs.len - 1)) |
| 217 | mismatch_pos := node.exprs[expr_idxs[midx]].pos() |
| 218 | c.error('expected ${expected_types.len} ${arg}, but got ${got_types.len}', mismatch_pos) |
| 219 | return |
| 220 | } |
| 221 | for i, exp_type in expected_types { |
| 222 | exprv := node.exprs[expr_idxs[i]] |
| 223 | if exprv is ast.Ident && exprv.or_expr.kind == .propagate_option { |
| 224 | if exp_type.has_flag(.option) { |
| 225 | c.warn('unwrapping option is redundant as the function returns option', node.pos) |
| 226 | } else { |
| 227 | c.error('should not unwrap option var on return, it could be none', node.pos) |
| 228 | } |
| 229 | } |
| 230 | got_type := c.unwrap_generic(got_types[i]) |
| 231 | if got_type.has_flag(.option) && (!exp_type.has_flag(.option) |
| 232 | || !c.check_types(got_type.clear_flag(.option), exp_type.clear_flag(.option))) { |
| 233 | c.error('cannot use `${c.table.type_to_str(got_type)}` as ${c.error_type_name(exp_type)} in return argument', |
| 234 | exprv.pos()) |
| 235 | } |
| 236 | if got_type.has_flag(.result) { |
| 237 | // Accept payload-equivalent aliases only when the expression is a |
| 238 | // call (optionally wrapped in `()`); the cgen alias clone path only |
| 239 | // handles bare calls today. For anything else, fall back to a |
| 240 | // strict identity check so cgen never emits a struct cast between |
| 241 | // distinct `_result_*` types (which C rejects). |
| 242 | payload_compat := if returns_call_like_result_expr(exprv) { |
| 243 | c.table.are_payloads_alias_compatible(got_type.clear_flag(.result), |
| 244 | exp_type.clear_flag(.result)) |
| 245 | } else { |
| 246 | got_type.clear_flag(.result) == exp_type.clear_flag(.result) |
| 247 | } |
| 248 | if !exp_type.has_flag(.result) || !payload_compat { |
| 249 | c.error('cannot use `${c.table.type_to_str(got_type)}` as ${c.error_type_name(exp_type)} in return argument', |
| 250 | exprv.pos()) |
| 251 | } |
| 252 | } |
| 253 | if exprv is ast.ComptimeCall && exprv.kind == .tmpl |
| 254 | && c.table.final_sym(exp_type).kind != .string { |
| 255 | c.error('cannot use `string` as type `${c.table.type_to_str(exp_type)}` in return argument', |
| 256 | exprv.pos) |
| 257 | } |
| 258 | if exprv !is ast.ComptimeCall { |
| 259 | got_type_sym := c.table.sym(got_type) |
| 260 | exp_type_sym := c.table.sym(exp_type) |
| 261 | if c.check_types(got_type, exp_type) { |
| 262 | if exp_type.is_unsigned() && got_type.is_int_literal() { |
| 263 | if exprv is ast.IntegerLiteral { |
| 264 | var := (node.exprs[expr_idxs[i]] as ast.IntegerLiteral).val |
| 265 | if var[0] == `-` { |
| 266 | c.note('cannot use a negative value as value of ${c.error_type_name(exp_type)} in return argument', |
| 267 | exprv.pos) |
| 268 | } |
| 269 | } |
| 270 | } |
| 271 | } else { |
| 272 | if c.pref.skip_unused && got_types[i].has_flag(.generic) { |
| 273 | c.table.used_features.comptime_syms[got_type] = true |
| 274 | } |
| 275 | if exp_type_sym.kind == .interface |
| 276 | || (exp_type_sym.kind == .generic_inst && exp_type_sym.info is ast.GenericInst |
| 277 | && c.table.type_symbols[exp_type_sym.info.parent_idx].kind == .interface) { |
| 278 | if c.type_implements(got_type, exp_type, node.pos) { |
| 279 | if !got_type.is_any_kind_of_pointer() && got_type_sym.kind != .interface |
| 280 | && !c.inside_unsafe { |
| 281 | c.mark_as_referenced(mut &node.exprs[expr_idxs[i]], true) |
| 282 | } |
| 283 | } |
| 284 | continue |
| 285 | } |
| 286 | exp_final_sym := c.table.final_sym(exp_type) |
| 287 | got_final_sym := c.table.final_sym(got_type) |
| 288 | if exp_final_sym.kind == .array_fixed && got_final_sym.kind == .array_fixed { |
| 289 | got_arr_sym := c.table.sym(c.cast_to_fixed_array_ret(got_type, got_final_sym)) |
| 290 | if (exp_final_sym.info as ast.ArrayFixed).is_compatible(got_arr_sym.info as ast.ArrayFixed) { |
| 291 | continue |
| 292 | } |
| 293 | } |
| 294 | // `fn foo() !int { return Err{} }` |
| 295 | if expected_fn_return_type_has_result && got_type_sym.kind == .struct |
| 296 | && c.type_implements(got_type, ast.error_type, node.pos) { |
| 297 | node.exprs[expr_idxs[i]] = ast.CastExpr{ |
| 298 | expr: exprv |
| 299 | typname: 'IError' |
| 300 | typ: ast.error_type |
| 301 | expr_type: got_type |
| 302 | pos: node.pos |
| 303 | } |
| 304 | node.types[expr_idxs[i]] = ast.error_type |
| 305 | continue |
| 306 | } |
| 307 | got_type_name := if got_type_sym.kind == .function { |
| 308 | '${c.table.type_to_str(got_type)}' |
| 309 | } else { |
| 310 | got_type_sym.name |
| 311 | } |
| 312 | // ignore generic lambda return in this phase |
| 313 | if c.inside_lambda && exp_type.has_flag(.generic) { |
| 314 | continue |
| 315 | } |
| 316 | if exp_final_sym.info is ast.ArrayFixed |
| 317 | && c.array_fixed_has_unresolved_size(exp_final_sym.info) { |
| 318 | continue |
| 319 | } |
| 320 | // In generic functions, scope variable types can be stale from a |
| 321 | // different instantiation pass. Skip the error if the original |
| 322 | // return type is generic — the cgen resolves types per-instantiation. |
| 323 | if c.table.cur_fn != unsafe { nil } && c.table.cur_fn.return_type.has_flag(.generic) |
| 324 | && c.table.cur_concrete_types.len > 0 { |
| 325 | continue |
| 326 | } |
| 327 | |
| 328 | c.error('cannot use `${got_type_name}` as ${c.error_type_name(exp_type)} in return argument', |
| 329 | exprv.pos()) |
| 330 | } |
| 331 | } |
| 332 | if exprv is ast.Ident { |
| 333 | if exprv.obj is ast.Var && exprv.obj.smartcasts.len > 0 { |
| 334 | orig_sym := c.table.final_sym(exprv.obj.orig_type) |
| 335 | if orig_sym.kind == .interface { |
| 336 | continue |
| 337 | } |
| 338 | } |
| 339 | } |
| 340 | if got_type.is_any_kind_of_pointer() && !exp_type.is_any_kind_of_pointer() |
| 341 | && !c.table.unaliased_type(exp_type).is_any_kind_of_pointer() { |
| 342 | if exprv.is_auto_deref_var() { |
| 343 | continue |
| 344 | } |
| 345 | c.add_error_detail('use `return *pointer` instead of `return pointer`, and just `return value` instead of `return &value`') |
| 346 | c.error('fn `${c.table.cur_fn.name}` expects you to return a non reference type `${c.table.type_to_str(exp_type)}`, but you are returning `${c.table.type_to_str(got_type)}` instead', |
| 347 | exprv.pos()) |
| 348 | } |
| 349 | if exp_type.is_any_kind_of_pointer() && !got_type.is_any_kind_of_pointer() |
| 350 | && !c.table.unaliased_type(got_type).is_any_kind_of_pointer() |
| 351 | && got_type != ast.int_literal_type && !c.pref.translated && !c.file.is_translated { |
| 352 | if exprv.is_auto_deref_var() { |
| 353 | continue |
| 354 | } |
| 355 | if c.table.final_sym(exp_type).kind == .interface |
| 356 | && c.table.final_sym(got_type).kind == .interface |
| 357 | && exp_type.deref().idx() == got_type.idx() { |
| 358 | continue |
| 359 | } |
| 360 | c.error('fn `${c.table.cur_fn.name}` expects you to return a reference type `${c.table.type_to_str(exp_type)}`, but you are returning `${c.table.type_to_str(got_type)}` instead', |
| 361 | exprv.pos()) |
| 362 | } |
| 363 | if exp_type.is_ptr() && got_type.is_ptr() { |
| 364 | r_expr := node.exprs[expr_idxs[i]] |
| 365 | if r_expr is ast.Ident { |
| 366 | mut ident_expr := r_expr |
| 367 | c.fail_if_stack_struct_action_outside_unsafe(mut ident_expr, 'returned') |
| 368 | } else if r_expr is ast.PrefixExpr && r_expr.op == .amp { |
| 369 | // &var |
| 370 | if r_expr.right is ast.Ident { |
| 371 | mut ident_expr := r_expr.right |
| 372 | c.fail_if_stack_struct_action_outside_unsafe(mut ident_expr, 'returned') |
| 373 | } |
| 374 | } |
| 375 | } |
| 376 | } |
| 377 | if exp_is_option && node.exprs.len > 0 { |
| 378 | expr0 := node.exprs[0] |
| 379 | if expr0 is ast.CallExpr { |
| 380 | if expr0.or_block.kind == .propagate_option && node.exprs.len == 1 { |
| 381 | v_name := if expr0.is_static_method { |
| 382 | expr0.name.all_before('__static__') + '.' + expr0.name.all_after('__static__') |
| 383 | } else { |
| 384 | expr0.name |
| 385 | } |
| 386 | c.error('`?` is not needed, use `return ${v_name}()`', expr0.pos) |
| 387 | } |
| 388 | } |
| 389 | } |
| 390 | } |
| 391 | |
| 392 | fn (mut c Checker) find_unreachable_statements_after_noreturn_calls(stmts []ast.Stmt) { |
| 393 | mut prev_stmt_was_noreturn_call := false |
| 394 | for stmt in stmts { |
| 395 | if stmt is ast.ExprStmt { |
| 396 | if stmt.expr is ast.CallExpr { |
| 397 | if prev_stmt_was_noreturn_call { |
| 398 | c.warn('unreachable code after a @[noreturn] call', stmt.pos) |
| 399 | return |
| 400 | } |
| 401 | prev_stmt_was_noreturn_call = stmt.expr.is_noreturn |
| 402 | } |
| 403 | } else { |
| 404 | prev_stmt_was_noreturn_call = false |
| 405 | } |
| 406 | } |
| 407 | } |
| 408 | |
| 409 | // Note: has_top_return/1 should be called on *already checked* stmts, |
| 410 | // which do have their stmt.expr.is_noreturn set properly: |
| 411 | fn (mut c Checker) has_top_return(stmts []ast.Stmt) bool { |
| 412 | for stmt in stmts { |
| 413 | match stmt { |
| 414 | ast.Return { |
| 415 | return true |
| 416 | } |
| 417 | ast.Block { |
| 418 | if c.has_top_return(stmt.stmts) { |
| 419 | return true |
| 420 | } |
| 421 | } |
| 422 | ast.ExprStmt { |
| 423 | if c.expr_never_falls_through(stmt.expr) { |
| 424 | return true |
| 425 | } |
| 426 | } |
| 427 | else {} |
| 428 | } |
| 429 | } |
| 430 | return false |
| 431 | } |
| 432 | |
| 433 | fn (mut c Checker) expr_never_falls_through(expr ast.Expr) bool { |
| 434 | match expr { |
| 435 | ast.CallExpr { |
| 436 | // do not ignore panic() calls on non checked stmts |
| 437 | return expr.is_noreturn |
| 438 | || (expr.is_method == false && expr.name == 'panic') |
| 439 | || c.call_expr_propagates_always_error(expr) |
| 440 | } |
| 441 | ast.ComptimeCall { |
| 442 | return expr.kind == .compile_error |
| 443 | } |
| 444 | ast.LockExpr { |
| 445 | return c.has_top_return(expr.stmts) |
| 446 | } |
| 447 | ast.IfExpr { |
| 448 | return c.has_top_return_in_if_expr(expr) |
| 449 | } |
| 450 | ast.MatchExpr { |
| 451 | return c.has_top_return_in_match_expr(expr) |
| 452 | } |
| 453 | else {} |
| 454 | } |
| 455 | |
| 456 | return false |
| 457 | } |
| 458 | |
| 459 | fn (mut c Checker) call_expr_propagates_always_error(node ast.CallExpr) bool { |
| 460 | if node.should_be_skipped || node.or_block.kind != .propagate_result { |
| 461 | return false |
| 462 | } |
| 463 | mut func := ast.Fn{} |
| 464 | if node.is_method { |
| 465 | if node.left_type == 0 { |
| 466 | return false |
| 467 | } |
| 468 | left_sym := c.table.sym(c.unwrap_generic(node.left_type)) |
| 469 | if left_sym.kind == .placeholder { |
| 470 | return false |
| 471 | } |
| 472 | func = c.table.find_method(left_sym, node.name) or { return false } |
| 473 | } else { |
| 474 | if node.name == '' { |
| 475 | return false |
| 476 | } |
| 477 | func = c.table.find_fn(node.name) or { return false } |
| 478 | } |
| 479 | return c.fn_always_errors(func) |
| 480 | } |
| 481 | |
| 482 | fn (mut c Checker) fn_always_errors(func ast.Fn) bool { |
| 483 | if func.name == '' || func.source_fn == unsafe { nil } || func.no_body || func.language != .v |
| 484 | || !func.return_type.has_flag(.result) { |
| 485 | return false |
| 486 | } |
| 487 | fkey := func.fkey() |
| 488 | if fkey in c.always_error_fn_cache { |
| 489 | return c.always_error_fn_cache[fkey] |
| 490 | } |
| 491 | if fkey in c.always_error_fn_in_progress { |
| 492 | return false |
| 493 | } |
| 494 | c.always_error_fn_in_progress[fkey] = true |
| 495 | defer { |
| 496 | c.always_error_fn_in_progress.delete(fkey) |
| 497 | } |
| 498 | fn_decl := unsafe { &ast.FnDecl(func.source_fn) } |
| 499 | result := c.stmts_always_error(fn_decl.stmts) |
| 500 | c.always_error_fn_cache[fkey] = result |
| 501 | return result |
| 502 | } |
| 503 | |
| 504 | fn (mut c Checker) stmts_always_error(stmts []ast.Stmt) bool { |
| 505 | for stmt in stmts { |
| 506 | if c.stmt_always_errors(stmt) { |
| 507 | return true |
| 508 | } |
| 509 | } |
| 510 | return false |
| 511 | } |
| 512 | |
| 513 | fn (mut c Checker) stmt_always_errors(stmt ast.Stmt) bool { |
| 514 | match stmt { |
| 515 | ast.Return { |
| 516 | return c.return_stmt_always_errors(stmt) |
| 517 | } |
| 518 | ast.Block { |
| 519 | return c.stmts_always_error(stmt.stmts) |
| 520 | } |
| 521 | ast.ExprStmt { |
| 522 | return c.expr_always_errors(stmt.expr) |
| 523 | } |
| 524 | ast.ForStmt { |
| 525 | return stmt.is_inf && stmt.stmts.len == 0 |
| 526 | } |
| 527 | else {} |
| 528 | } |
| 529 | |
| 530 | return false |
| 531 | } |
| 532 | |
| 533 | fn (mut c Checker) expr_always_errors(expr ast.Expr) bool { |
| 534 | match expr { |
| 535 | ast.CallExpr { |
| 536 | return expr.is_noreturn || c.call_expr_propagates_always_error(expr) |
| 537 | } |
| 538 | ast.ComptimeCall { |
| 539 | return expr.kind == .compile_error |
| 540 | } |
| 541 | ast.IfExpr { |
| 542 | return c.if_expr_always_errors(expr) |
| 543 | } |
| 544 | ast.MatchExpr { |
| 545 | return c.match_expr_always_errors(expr) |
| 546 | } |
| 547 | ast.LockExpr { |
| 548 | return c.stmts_always_error(expr.stmts) |
| 549 | } |
| 550 | else {} |
| 551 | } |
| 552 | |
| 553 | return false |
| 554 | } |
| 555 | |
| 556 | fn (mut c Checker) return_stmt_always_errors(node ast.Return) bool { |
| 557 | if node.types.len == 1 && c.table.unaliased_type(node.types[0]).idx() == ast.error_type_idx { |
| 558 | return true |
| 559 | } |
| 560 | return false |
| 561 | } |
| 562 | |
| 563 | fn (mut c Checker) has_top_return_in_if_expr(if_expr ast.IfExpr) bool { |
| 564 | if if_expr.branches.len < 2 || !if_expr.has_else { |
| 565 | return false |
| 566 | } |
| 567 | for branch in if_expr.branches { |
| 568 | if !c.has_top_return(branch.stmts) { |
| 569 | return false |
| 570 | } |
| 571 | } |
| 572 | return true |
| 573 | } |
| 574 | |
| 575 | fn (mut c Checker) if_expr_always_errors(if_expr ast.IfExpr) bool { |
| 576 | if if_expr.branches.len < 2 || !if_expr.has_else { |
| 577 | return false |
| 578 | } |
| 579 | for branch in if_expr.branches { |
| 580 | if !c.stmts_always_error(branch.stmts) { |
| 581 | return false |
| 582 | } |
| 583 | } |
| 584 | return true |
| 585 | } |
| 586 | |
| 587 | fn (mut c Checker) has_top_return_in_match_expr(match_expr ast.MatchExpr) bool { |
| 588 | if match_expr.branches.len == 0 { |
| 589 | return false |
| 590 | } |
| 591 | if match_expr.is_comptime { |
| 592 | mut has_else := false |
| 593 | for branch in match_expr.branches { |
| 594 | if branch.is_else { |
| 595 | has_else = true |
| 596 | break |
| 597 | } |
| 598 | for expr in branch.exprs { |
| 599 | if expr is ast.Ident && expr.name == '\$else' { |
| 600 | has_else = true |
| 601 | break |
| 602 | } |
| 603 | } |
| 604 | if has_else { |
| 605 | break |
| 606 | } |
| 607 | } |
| 608 | if has_else { |
| 609 | for branch in match_expr.branches { |
| 610 | if !c.has_top_return(branch.stmts) { |
| 611 | return false |
| 612 | } |
| 613 | } |
| 614 | return true |
| 615 | } |
| 616 | return false |
| 617 | } |
| 618 | for branch in match_expr.branches { |
| 619 | if !c.has_top_return(branch.stmts) { |
| 620 | return false |
| 621 | } |
| 622 | } |
| 623 | return true |
| 624 | } |
| 625 | |
| 626 | fn (mut c Checker) match_expr_always_errors(match_expr ast.MatchExpr) bool { |
| 627 | if match_expr.branches.len == 0 { |
| 628 | return false |
| 629 | } |
| 630 | if match_expr.is_comptime { |
| 631 | mut has_else := false |
| 632 | for branch in match_expr.branches { |
| 633 | if branch.is_else { |
| 634 | has_else = true |
| 635 | break |
| 636 | } |
| 637 | for expr in branch.exprs { |
| 638 | if expr is ast.Ident && expr.name == '\$else' { |
| 639 | has_else = true |
| 640 | break |
| 641 | } |
| 642 | } |
| 643 | if has_else { |
| 644 | break |
| 645 | } |
| 646 | } |
| 647 | if !has_else { |
| 648 | return false |
| 649 | } |
| 650 | } |
| 651 | for branch in match_expr.branches { |
| 652 | if !c.stmts_always_error(branch.stmts) { |
| 653 | return false |
| 654 | } |
| 655 | } |
| 656 | return true |
| 657 | } |
| 658 | |
| 659 | fn (mut c Checker) check_noreturn_fn_decl(mut node ast.FnDecl) { |
| 660 | if !node.is_noreturn { |
| 661 | return |
| 662 | } |
| 663 | if node.no_body { |
| 664 | return |
| 665 | } |
| 666 | if node.return_type != ast.void_type { |
| 667 | c.error('[noreturn] functions cannot have return types', node.pos) |
| 668 | } |
| 669 | if uses_return_stmt(node.stmts) { |
| 670 | c.error('[noreturn] functions cannot use return statements', node.pos) |
| 671 | } |
| 672 | mut pos := node.pos |
| 673 | mut is_valid_end_of_noreturn_fn := false |
| 674 | if node.stmts.len != 0 { |
| 675 | last_stmt := node.stmts.last() |
| 676 | match last_stmt { |
| 677 | ast.ExprStmt { |
| 678 | if last_stmt.expr is ast.CallExpr { |
| 679 | if last_stmt.expr.should_be_skipped { |
| 680 | c.error('@[noreturn] functions cannot end with a skippable `@[if ..]` call', |
| 681 | last_stmt.pos) |
| 682 | return |
| 683 | } |
| 684 | if last_stmt.expr.is_noreturn { |
| 685 | is_valid_end_of_noreturn_fn = true |
| 686 | } |
| 687 | } |
| 688 | } |
| 689 | ast.ForStmt { |
| 690 | if last_stmt.is_inf && last_stmt.stmts.len == 0 { |
| 691 | is_valid_end_of_noreturn_fn = true |
| 692 | } |
| 693 | } |
| 694 | else {} |
| 695 | } |
| 696 | |
| 697 | if !is_valid_end_of_noreturn_fn { |
| 698 | pos = last_stmt.pos |
| 699 | } |
| 700 | } |
| 701 | if !is_valid_end_of_noreturn_fn { |
| 702 | c.error('@[noreturn] functions should end with a call to another @[noreturn] function, or with an infinite `for {}` loop', |
| 703 | pos) |
| 704 | } |
| 705 | } |
| 706 | |
| 707 | fn uses_return_stmt(stmts []ast.Stmt) bool { |
| 708 | if stmts.len == 0 { |
| 709 | return false |
| 710 | } |
| 711 | for stmt in stmts { |
| 712 | match stmt { |
| 713 | ast.Return { |
| 714 | return true |
| 715 | } |
| 716 | ast.Block { |
| 717 | if uses_return_stmt(stmt.stmts) { |
| 718 | return true |
| 719 | } |
| 720 | } |
| 721 | ast.ExprStmt { |
| 722 | match stmt.expr { |
| 723 | ast.CallExpr { |
| 724 | if uses_return_stmt(stmt.expr.or_block.stmts) { |
| 725 | return true |
| 726 | } |
| 727 | } |
| 728 | ast.MatchExpr { |
| 729 | for b in stmt.expr.branches { |
| 730 | if uses_return_stmt(b.stmts) { |
| 731 | return true |
| 732 | } |
| 733 | } |
| 734 | } |
| 735 | ast.SelectExpr { |
| 736 | for b in stmt.expr.branches { |
| 737 | if uses_return_stmt(b.stmts) { |
| 738 | return true |
| 739 | } |
| 740 | } |
| 741 | } |
| 742 | ast.IfExpr { |
| 743 | for b in stmt.expr.branches { |
| 744 | if uses_return_stmt(b.stmts) { |
| 745 | return true |
| 746 | } |
| 747 | } |
| 748 | } |
| 749 | else {} |
| 750 | } |
| 751 | } |
| 752 | ast.ForStmt { |
| 753 | if uses_return_stmt(stmt.stmts) { |
| 754 | return true |
| 755 | } |
| 756 | } |
| 757 | ast.ForCStmt { |
| 758 | if uses_return_stmt(stmt.stmts) { |
| 759 | return true |
| 760 | } |
| 761 | } |
| 762 | ast.ForInStmt { |
| 763 | if uses_return_stmt(stmt.stmts) { |
| 764 | return true |
| 765 | } |
| 766 | } |
| 767 | else {} |
| 768 | } |
| 769 | } |
| 770 | return false |
| 771 | } |
| 772 | |
| 773 | fn is_noreturn_callexpr(expr ast.Expr) bool { |
| 774 | if expr is ast.CallExpr { |
| 775 | return expr.is_noreturn |
| 776 | } |
| 777 | return false |
| 778 | } |
| 779 | |