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InternPool: add representation for value of empty enums and unions

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This is a bit odd, because this value doesn't actually exist:
see #15909. This gets all the empty enum/union behavior tests passing.

Also adds an assertion to `Sema.analyzeBodyInner` which would have
helped figure out the issue here much more quickly.
This commit is contained in:
mlugg 2023-05-31 04:42:18 +01:00 committed by Andrew Kelley
parent 99531b0d52
commit a0d4ef0acf
10 changed files with 66 additions and 13 deletions
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24
src/InternPool.zig
View File

@ -206,6 +206,10 @@ pub const Key = union(enum) {
enum_literal: NullTerminatedString,
/// A specific enum tag, indicated by the integer tag value.
enum_tag: Key.EnumTag,
/// An empty enum or union. TODO: this value's existence is strange, because such a type in
/// reality has no values. See #15909.
/// Payload is the type for which we are an empty value.
empty_enum_value: Index,
float: Key.Float,
ptr: Ptr,
opt: Opt,
@ -670,6 +674,7 @@ pub const Key = union(enum) {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.inferred_error_set_type,
=> |info| {
var hasher = std.hash.Wyhash.init(seed);
@ -957,6 +962,10 @@ pub const Key = union(enum) {
const b_info = b.enum_tag;
return std.meta.eql(a_info, b_info);
},
.empty_enum_value => |a_info| {
const b_info = b.empty_enum_value;
return a_info == b_info;
},
.variable => |a_info| {
const b_info = b.variable;
@ -1192,6 +1201,7 @@ pub const Key = union(enum) {
.enum_literal => .enum_literal_type,
.undef => |x| x,
.empty_enum_value => |x| x,
.simple_value => |s| switch (s) {
.undefined => .undefined_type,
@ -1980,6 +1990,7 @@ pub const Tag = enum(u8) {
/// The set of values that are encoded this way is:
/// * An array or vector which has length 0.
/// * A struct which has all fields comptime-known.
/// * An empty enum or union. TODO: this value's existence is strange, because such a type in reality has no values. See #15909
/// data is Index of the type, which is known to be zero bits at runtime.
only_possible_value,
/// data is extra index to Key.Union.
@ -2952,6 +2963,13 @@ pub fn indexToKey(ip: *const InternPool, index: Index) Key {
} };
},
.type_enum_auto,
.type_enum_explicit,
.type_union_tagged,
.type_union_untagged,
.type_union_safety,
=> .{ .empty_enum_value = ty },
else => unreachable,
};
},
@ -3755,6 +3773,11 @@ pub fn get(ip: *InternPool, gpa: Allocator, key: Key) Allocator.Error!Index {
});
},
.empty_enum_value => |enum_or_union_ty| ip.items.appendAssumeCapacity(.{
.tag = .only_possible_value,
.data = @enumToInt(enum_or_union_ty),
}),
.float => |float| {
switch (float.ty) {
.f16_type => ip.items.appendAssumeCapacity(.{
@ -5416,7 +5439,6 @@ pub fn isNoReturn(ip: *const InternPool, ty: Index) bool {
.noreturn_type => true,
else => switch (ip.indexToKey(ty)) {
.error_set_type => |error_set_type| error_set_type.names.len == 0,
.enum_type => |enum_type| enum_type.names.len == 0,
else => false,
},
};

29
src/Sema.zig
View File

@ -1725,8 +1725,12 @@ fn analyzeBodyInner(
break :blk Air.Inst.Ref.void_value;
},
};
if (sema.isNoReturn(air_inst))
if (sema.isNoReturn(air_inst)) {
// We're going to assume that the body itself is noreturn, so let's ensure that now
assert(block.instructions.items.len > 0);
assert(sema.isNoReturn(Air.indexToRef(block.instructions.items[block.instructions.items.len - 1])));
break always_noreturn;
}
map.putAssumeCapacity(inst, air_inst);
i += 1;
};
@ -32150,6 +32154,7 @@ pub fn resolveTypeRequiresComptime(sema: *Sema, ty: Type) CompileError!bool {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -33015,10 +33020,6 @@ fn semaUnionFields(mod: *Module, union_obj: *Module.Union) CompileError!void {
enum_field_names = try sema.arena.alloc(InternPool.NullTerminatedString, fields_len);
}
if (fields_len == 0) {
return;
}
const bits_per_field = 4;
const fields_per_u32 = 32 / bits_per_field;
const bit_bags_count = std.math.divCeil(usize, fields_len, fields_per_u32) catch unreachable;
@ -33301,7 +33302,7 @@ fn generateUnionTagTypeNumbered(
.decl = new_decl_index,
.namespace = .none,
.tag_ty = if (enum_field_vals.len == 0)
.noreturn_type
(try mod.intType(.unsigned, 0)).toIntern()
else
mod.intern_pool.typeOf(enum_field_vals[0]),
.names = enum_field_names,
@ -33351,7 +33352,7 @@ fn generateUnionTagTypeSimple(
.decl = new_decl_index,
.namespace = .none,
.tag_ty = if (enum_field_names.len == 0)
.noreturn_type
(try mod.intType(.unsigned, 0)).toIntern()
else
(try mod.smallestUnsignedInt(enum_field_names.len - 1)).toIntern(),
.names = enum_field_names,
@ -33590,7 +33591,10 @@ pub fn typeHasOnePossibleValue(sema: *Sema, ty: Type) CompileError!?Value {
const tag_val = (try sema.typeHasOnePossibleValue(union_obj.tag_ty)) orelse
return null;
const fields = union_obj.fields.values();
if (fields.len == 0) return Value.@"unreachable";
if (fields.len == 0) {
const only = try mod.intern(.{ .empty_enum_value = ty.toIntern() });
return only.toValue();
}
const only_field = fields[0];
if (only_field.ty.eql(resolved_ty, sema.mod)) {
const msg = try Module.ErrorMsg.create(
@ -33630,7 +33634,10 @@ pub fn typeHasOnePossibleValue(sema: *Sema, ty: Type) CompileError!?Value {
if (enum_type.tag_ty.toType().hasRuntimeBits(mod)) return null;
switch (enum_type.names.len) {
0 => return Value.@"unreachable",
0 => {
const only = try mod.intern(.{ .empty_enum_value = ty.toIntern() });
return only.toValue();
},
1 => return try mod.getCoerced((if (enum_type.values.len == 0)
try mod.intern(.{ .int = .{
.ty = enum_type.tag_ty,
@ -33655,6 +33662,7 @@ pub fn typeHasOnePossibleValue(sema: *Sema, ty: Type) CompileError!?Value {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -34143,6 +34151,7 @@ pub fn typeRequiresComptime(sema: *Sema, ty: Type) CompileError!bool {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -34848,7 +34857,7 @@ fn errorSetMerge(sema: *Sema, lhs: Type, rhs: Type) !Type {
/// Avoids crashing the compiler when asking if inferred allocations are noreturn.
fn isNoReturn(sema: *Sema, ref: Air.Inst.Ref) bool {
if (ref == .noreturn_type) return true;
if (ref == .unreachable_value) return true;
if (Air.refToIndex(ref)) |inst| switch (sema.air_instructions.items(.tag)[inst]) {
.inferred_alloc, .inferred_alloc_comptime => return false,
else => {},

1
src/TypedValue.zig
View File

@ -248,6 +248,7 @@ pub fn print(
try writer.writeAll(")");
return;
},
.empty_enum_value => return writer.writeAll("(empty enum value)"),
.float => |float| switch (float.storage) {
inline else => |x| return writer.print("{}", .{x}),
},

1
src/arch/wasm/CodeGen.zig
View File

@ -3156,6 +3156,7 @@ fn lowerConstant(func: *CodeGen, arg_val: Value, ty: Type) InnerError!WValue {
.extern_func,
.func,
.enum_literal,
.empty_enum_value,
=> unreachable, // non-runtime values
.int => {
const int_info = ty.intInfo(mod);

1
src/codegen.zig
View File

@ -242,6 +242,7 @@ pub fn generateSymbol(
.extern_func,
.func,
.enum_literal,
.empty_enum_value,
=> unreachable, // non-runtime values
.int => {
const abi_size = math.cast(usize, typed_value.ty.abiSize(mod)) orelse return error.Overflow;

1
src/codegen/c.zig
View File

@ -946,6 +946,7 @@ pub const DeclGen = struct {
.extern_func,
.func,
.enum_literal,
.empty_enum_value,
=> unreachable, // non-runtime values
.int => |int| switch (int.storage) {
.u64, .i64, .big_int => try writer.print("{}", .{try dg.fmtIntLiteral(ty, val, location)}),

1
src/codegen/llvm.zig
View File

@ -3246,6 +3246,7 @@ pub const DeclGen = struct {
},
.variable,
.enum_literal,
.empty_enum_value,
=> unreachable, // non-runtime values
.extern_func, .func => {
const fn_decl_index = switch (val_key) {

1
src/codegen/spirv.zig
View File

@ -660,6 +660,7 @@ pub const DeclGen = struct {
.extern_func,
.func,
.enum_literal,
.empty_enum_value,
=> unreachable, // non-runtime values
.int => try self.addInt(ty, val),
.err => |err| {

19
src/type.zig
View File

@ -439,6 +439,7 @@ pub const Type = struct {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -655,6 +656,7 @@ pub const Type = struct {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -764,6 +766,7 @@ pub const Type = struct {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -1098,6 +1101,7 @@ pub const Type = struct {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -1515,6 +1519,7 @@ pub const Type = struct {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -1749,6 +1754,7 @@ pub const Type = struct {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -2302,6 +2308,7 @@ pub const Type = struct {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -2584,7 +2591,10 @@ pub const Type = struct {
.union_type => |union_type| {
const union_obj = mod.unionPtr(union_type.index);
const tag_val = (try union_obj.tag_ty.onePossibleValue(mod)) orelse return null;
if (union_obj.fields.count() == 0) return Value.@"unreachable";
if (union_obj.fields.count() == 0) {
const only = try mod.intern(.{ .empty_enum_value = ty.toIntern() });
return only.toValue();
}
const only_field = union_obj.fields.values()[0];
const val_val = (try only_field.ty.onePossibleValue(mod)) orelse return null;
const only = try mod.intern(.{ .un = .{
@ -2613,7 +2623,10 @@ pub const Type = struct {
if (enum_type.tag_ty.toType().hasRuntimeBits(mod)) return null;
switch (enum_type.names.len) {
0 => return Value.@"unreachable",
0 => {
const only = try mod.intern(.{ .empty_enum_value = ty.toIntern() });
return only.toValue();
},
1 => {
if (enum_type.values.len == 0) {
const only = try mod.intern(.{ .enum_tag = .{
@ -2645,6 +2658,7 @@ pub const Type = struct {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,
@ -2790,6 +2804,7 @@ pub const Type = struct {
.error_union,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
.ptr,
.opt,

1
src/value.zig
View File

@ -441,6 +441,7 @@ pub const Value = struct {
.err,
.enum_literal,
.enum_tag,
.empty_enum_value,
.float,
=> val,