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fix(types): reject unknown type names instead of silent empty struct (issue 0064)

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An identifier used in a type position that resolved to nothing fell through
to `type_bridge.resolveTypeName`'s empty-struct-stub fallback, silently
interning a 0-field struct named after the identifier. A value parameter
mistakenly used as a type (`(T: Type, ...) -> T`, missing the `$`) or a
typo'd type name therefore compiled and ran, rendering as `T{}`.

New post-scan diagnostic pass `checkUnknownTypeNames` (lower.zig Pass 1f)
walks every main-file function signature and non-generic struct field type
and rejects any leaf name that is not a primitive, an in-scope generic param
(`$T` / `type_params`), a declared type, or a real (non-stub) registered
type. The load-bearing empty-struct stub is left intact — forward references
and foreign-class opaque types still depend on it during the scan — and the
pass runs before body lowering, so `hasErrors()` halts the build before any
stub reaches codegen.

A value param used as a type gets a tailored hint to write `$T: Type`; a
genuine unknown gets "unknown type 'X'". Imported concrete types are
recognized via the type table, and inline compound spellings (`[:0]u8`),
arbitrary-width ints (`u1`/`u2`), and `$`-introduced generics (`-> $R`) are
exempted to avoid false positives.

Regressions: examples/1111 (tailored hint) + 1112 (typo'd field type).
This commit is contained in:
agra
2026-06-02 10:24:30 +03:00
parent 9214eefba1
commit c490ffcfe9
10 changed files with 249 additions and 0 deletions
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185
src/ir/lower.zig
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@@ -367,6 +367,12 @@ pub const Lowering = struct {
// before body lowering — purely a diagnostic pass; `core.zig` halts on
// any error before codegen.
self.checkErrorFlow(decls);
// Pass 1f: reject identifiers used in a type position that name no
// declared type / primitive / in-scope generic param (issue 0064).
// Runs after scanning (so every real type name is registered) and
// before body lowering, so the diagnostic halts via `core.zig`
// `hasErrors()` before the empty-struct stub can reach codegen.
self.checkUnknownTypeNames(decls);
// Pass 2: lower main (and comptime side-effects)
self.lowerMainAndComptime(decls);
// Pass 3: lower deferred functions (any_to_string etc.) now that all types are registered
@@ -518,6 +524,185 @@ pub const Lowering = struct {
}
}
/// Diagnostic pass (issue 0064): reject an identifier used in a type
/// position that names no declared type, primitive, or in-scope generic
/// type parameter. Without it, `type_bridge.resolveTypeName`'s
/// empty-struct-stub fallback silently fabricates a 0-field struct named
/// after the unknown identifier — so a value param mistakenly used as a
/// type (`(T: Type, …) -> T`, missing the `$`) or a typo'd type name
/// compiles and runs, rendering as `T{}`. Main-file decls only; imported /
/// library modules are trusted, matching `checkErrorFlow`.
fn checkUnknownTypeNames(self: *Lowering, decls: []const *const Node) void {
if (self.diagnostics == null) return;
var declared = std.StringHashMap(void).init(self.alloc);
defer declared.deinit();
self.collectDeclaredTypeNames(decls, &declared);
for (decls) |decl| {
if (self.main_file) |mf| {
if (decl.source_file) |sf| {
if (!std.mem.eql(u8, sf, mf)) continue;
}
}
switch (decl.data) {
.fn_decl => self.checkFnSignatureTypes(&decl.data.fn_decl, &declared),
.struct_decl => |sd| self.checkStructFieldTypes(&sd, &declared),
.const_decl => |cd| switch (cd.value.data) {
.fn_decl => self.checkFnSignatureTypes(&cd.value.data.fn_decl, &declared),
.struct_decl => |sd| self.checkStructFieldTypes(&sd, &declared),
else => {},
},
else => {},
}
}
}
/// Collect every top-level name that can legitimately appear in a type
/// position: const-decl names (covers `T :: struct/enum/union/error/alias`
/// and value consts), plus the scan-populated foreign-class / generic-
/// template / protocol / alias maps. Built across ALL files so a main-file
/// reference to an imported type isn't flagged.
fn collectDeclaredTypeNames(self: *Lowering, decls: []const *const Node, out: *std.StringHashMap(void)) void {
for (decls) |decl| {
switch (decl.data) {
.const_decl => |cd| out.put(cd.name, {}) catch {},
.struct_decl => |sd| out.put(sd.name, {}) catch {},
else => {},
}
}
var it_fc = self.foreign_class_map.keyIterator();
while (it_fc.next()) |k| out.put(k.*, {}) catch {};
var it_tmpl = self.struct_template_map.keyIterator();
while (it_tmpl.next()) |k| out.put(k.*, {}) catch {};
var it_pd = self.protocol_decl_map.keyIterator();
while (it_pd.next()) |k| out.put(k.*, {}) catch {};
var it_pa = self.protocol_ast_map.keyIterator();
while (it_pa.next()) |k| out.put(k.*, {}) catch {};
var it_al = self.type_alias_map.keyIterator();
while (it_al.next()) |k| out.put(k.*, {}) catch {};
}
fn checkStructFieldTypes(self: *Lowering, sd: *const ast.StructDecl, declared: *std.StringHashMap(void)) void {
// Generic struct fields reference the struct's own type params ($T) —
// resolved at instantiation, not here.
if (sd.type_params.len != 0) return;
for (sd.field_types) |ft| self.checkTypeNodeForUnknown(ft, declared, &.{}, &.{});
}
fn checkFnSignatureTypes(self: *Lowering, fd: *const ast.FnDecl, declared: *std.StringHashMap(void)) void {
// Value params declared `: Type` (no `$`) — using one in a type
// position is the issue-0064 misuse; surface a tailored hint.
var type_vals = std.ArrayList([]const u8).empty;
defer type_vals.deinit(self.alloc);
for (fd.params) |p| {
if (p.type_expr.data == .type_expr) {
const cn = p.type_expr.data.type_expr.name;
if (std.mem.eql(u8, cn, "Type") or std.mem.eql(u8, cn, "type")) {
type_vals.append(self.alloc, p.name) catch {};
}
}
}
for (fd.params) |p| self.checkTypeNodeForUnknown(p.type_expr, declared, fd.type_params, type_vals.items);
if (fd.return_type) |rt| self.checkTypeNodeForUnknown(rt, declared, fd.type_params, type_vals.items);
}
/// Recurse a type-annotation node to its leaf names, reporting any unknown.
fn checkTypeNodeForUnknown(
self: *Lowering,
node: *const Node,
declared: *std.StringHashMap(void),
in_scope: []const ast.StructTypeParam,
type_vals: []const []const u8,
) void {
switch (node.data) {
// A `$`-prefixed name (`-> $R`) introduces/references a generic type
// param inline — always valid in a type position.
.type_expr => |te| if (!te.is_generic) self.reportIfUnknownType(te.name, node.span, declared, in_scope, type_vals),
.identifier => |id| self.reportIfUnknownType(id.name, node.span, declared, in_scope, type_vals),
.pointer_type_expr => |pt| self.checkTypeNodeForUnknown(pt.pointee_type, declared, in_scope, type_vals),
.many_pointer_type_expr => |mp| self.checkTypeNodeForUnknown(mp.element_type, declared, in_scope, type_vals),
.slice_type_expr => |st| self.checkTypeNodeForUnknown(st.element_type, declared, in_scope, type_vals),
.optional_type_expr => |ot| self.checkTypeNodeForUnknown(ot.inner_type, declared, in_scope, type_vals),
.array_type_expr => |at| self.checkTypeNodeForUnknown(at.element_type, declared, in_scope, type_vals),
.tuple_type_expr => |tt| for (tt.field_types) |ft| self.checkTypeNodeForUnknown(ft, declared, in_scope, type_vals),
.function_type_expr => |ft| {
for (ft.param_types) |pt| self.checkTypeNodeForUnknown(pt, declared, in_scope, type_vals);
if (ft.return_type) |rt| self.checkTypeNodeForUnknown(rt, declared, in_scope, type_vals);
},
.closure_type_expr => |ct| {
// Variadic type-pack closures (`Closure(..$args) -> R`) resolve
// their projections specially — don't walk them here.
if (ct.pack_name != null) return;
for (ct.param_types) |pt| self.checkTypeNodeForUnknown(pt, declared, in_scope, type_vals);
if (ct.return_type) |rt| self.checkTypeNodeForUnknown(rt, declared, in_scope, type_vals);
},
// Builtin constructors (Vector) and generic templates resolve the
// base name specially; just check the type args.
.parameterized_type_expr => |pt| for (pt.args) |a| self.checkTypeNodeForUnknown(a, declared, in_scope, type_vals),
else => {},
}
}
fn reportIfUnknownType(
self: *Lowering,
name: []const u8,
span: ?ast.Span,
declared: *std.StringHashMap(void),
in_scope: []const ast.StructTypeParam,
type_vals: []const []const u8,
) void {
// Only bare identifiers are validated. Inline-spelled compound types
// (`[:0]u8`, `mod.Type`, …) carry non-identifier characters — trust them.
if (!isIdentLike(name)) return;
if (isBuiltinTypeName(name)) return;
for (in_scope) |tp| if (std.mem.eql(u8, tp.name, name)) return;
if (declared.contains(name)) return;
// Registered as a real (non-stub) type — covers imported concrete
// structs / enums / unions absent from the main-file decl list. A
// fabricated empty-struct stub (the very thing we're catching) is the
// sole 0-field-struct case, so it doesn't suppress the diagnostic.
const sid = self.module.types.internString(name);
if (self.module.types.findByName(sid)) |tid| {
const info = self.module.types.get(tid);
const empty_struct_stub = info == .@"struct" and info.@"struct".fields.len == 0;
if (!empty_struct_stub) return;
}
const diags = self.diagnostics orelse return;
for (type_vals) |tv| {
if (std.mem.eql(u8, tv, name)) {
diags.addFmt(.err, span, "'{s}' is a value parameter, not a type; introduce a generic type parameter with `${s}: Type`", .{ name, name });
return;
}
}
diags.addFmt(.err, span, "unknown type '{s}'", .{name});
}
fn isBuiltinTypeName(name: []const u8) bool {
if (type_bridge.resolveTypePrimitive(name) != null) return true;
// Arbitrary-width integers / floats: u1, s7, u128, f16, f80, …
if (name.len >= 2 and (name[0] == 'u' or name[0] == 's' or name[0] == 'f')) {
var all_digits = true;
for (name[1..]) |c| {
if (!std.ascii.isDigit(c)) {
all_digits = false;
break;
}
}
if (all_digits) return true;
}
const extra = [_][]const u8{ "Type", "type", "int", "float", "Self", "self", "any", "noreturn", "usize", "isize", "comptime_int", "comptime_float" };
for (extra) |e| if (std.mem.eql(u8, name, e)) return true;
return false;
}
fn isIdentLike(name: []const u8) bool {
if (name.len == 0) return false;
if (!(std.ascii.isAlphabetic(name[0]) or name[0] == '_')) return false;
for (name) |c| {
if (!(std.ascii.isAlphanumeric(c) or c == '_')) return false;
}
return true;
}
/// Analyze one function (or lambda) body as its own boundary — a fresh
/// binding context and an empty proven set.
fn analyzeFnBody(self: *Lowering, body: *const Node) void {