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sema: Improvements to union and struct layout resolution to solve a false-positive circular dependency error #17490

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sema: Improvements to union and struct layout resolution to solve a false-positive circular dependency error #17490

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40 changes: 36 additions & 4 deletions src/InternPool.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -492,7 +492,7 @@ pub const Key = union(enum) {

/// The returned pointer expires with any addition to the `InternPool`.
/// Asserts the struct is not packed.
pub fn flagsPtr(self: @This(), ip: *InternPool) *Tag.TypeStruct.Flags {
pub fn flagsPtr(self: @This(), ip: *const InternPool) *Tag.TypeStruct.Flags {
assert(self.layout != .Packed);
const flags_field_index = std.meta.fieldIndex(Tag.TypeStruct, "flags").?;
return @ptrCast(&ip.extra.items[self.extra_index + flags_field_index]);
Expand Down Expand Up @@ -688,6 +688,18 @@ pub const Key = union(enum) {
return @ptrCast(&ip.extra.items[self.extra_index + flags_field_index]);
}

/// The returned pointer expires with any addition to the `InternPool`.
pub fn size(self: @This(), ip: *InternPool) *u32 {
const size_field_index = std.meta.fieldIndex(Tag.TypeUnion, "size").?;
return @ptrCast(&ip.extra.items[self.extra_index + size_field_index]);
}

/// The returned pointer expires with any addition to the `InternPool`.
pub fn padding(self: @This(), ip: *InternPool) *u32 {
const padding_field_index = std.meta.fieldIndex(Tag.TypeUnion, "padding").?;
return @ptrCast(&ip.extra.items[self.extra_index + padding_field_index]);
}

pub fn haveFieldTypes(self: @This(), ip: *const InternPool) bool {
return self.flagsPtr(ip).status.haveFieldTypes();
}
Expand Down Expand Up @@ -1737,6 +1749,10 @@ pub const UnionType = struct {
enum_tag_ty: Index,
/// The integer tag type of the enum.
int_tag_ty: Index,
/// ABI size of the union, including padding
size: u64,
/// Trailing padding bytes
padding: u32,
/// List of field names in declaration order.
field_names: NullTerminatedString.Slice,
/// List of field types in declaration order.
Expand Down Expand Up @@ -1823,6 +1839,10 @@ pub const UnionType = struct {
return self.flagsPtr(ip).runtime_tag.hasTag();
}

pub fn haveFieldTypes(self: UnionType, ip: *const InternPool) bool {
return self.flagsPtr(ip).status.haveFieldTypes();
}

pub fn haveLayout(self: UnionType, ip: *const InternPool) bool {
return self.flagsPtr(ip).status.haveLayout();
}
Expand Down Expand Up @@ -1860,6 +1880,8 @@ pub fn loadUnionType(ip: *InternPool, key: Key.UnionType) UnionType {
.namespace = type_union.data.namespace,
.enum_tag_ty = enum_ty,
.int_tag_ty = enum_info.tag_ty,
.size = type_union.data.padding,
.padding = type_union.data.padding,
.field_names = enum_info.names,
.names_map = enum_info.names_map,
.field_types = .{
Expand Down Expand Up @@ -2925,6 +2947,10 @@ pub const Tag = enum(u8) {
/// 1. field align: Alignment for each field; declaration order
pub const TypeUnion = struct {
flags: Flags,
// Only valid after .have_layout
size: u32,
// Only valid after .have_layout
padding: u32,
decl: Module.Decl.Index,
namespace: Module.Namespace.Index,
/// The enum that provides the list of field names and values.
Expand All @@ -2939,7 +2965,9 @@ pub const Tag = enum(u8) {
status: UnionType.Status,
requires_comptime: RequiresComptime,
assumed_runtime_bits: bool,
_: u21 = 0,
field_runtime_bits_wip: bool,
alignment: Alignment,
_: u14 = 0,
};
};

Expand Down Expand Up @@ -2999,11 +3027,12 @@ pub const Tag = enum(u8) {
requires_comptime: RequiresComptime,
is_tuple: bool,
assumed_runtime_bits: bool,
field_runtime_bits_wip: bool,
has_namespace: bool,
any_comptime_fields: bool,
any_default_inits: bool,
any_aligned_fields: bool,
/// `undefined` until the layout_resolved
/// `.none` until layout_resolved
alignment: Alignment,
/// Dependency loop detection when resolving struct alignment.
alignment_wip: bool,
Expand All @@ -3018,7 +3047,7 @@ pub const Tag = enum(u8) {
// which `layout_resolved` does not ensure.
fully_resolved: bool,

_: u11 = 0,
_: u10 = 0,
};
};
};
Expand Down Expand Up @@ -5213,6 +5242,8 @@ pub fn getUnionType(ip: *InternPool, gpa: Allocator, ini: UnionTypeInit) Allocat

const union_type_extra_index = ip.addExtraAssumeCapacity(Tag.TypeUnion{
.flags = ini.flags,
.size = std.math.maxInt(u32),
.padding = std.math.maxInt(u32),
.decl = ini.decl,
.namespace = ini.namespace,
.tag_ty = ini.enum_tag_ty,
Expand Down Expand Up @@ -5352,6 +5383,7 @@ pub fn getStructType(
.requires_comptime = ini.requires_comptime,
.is_tuple = ini.is_tuple,
.assumed_runtime_bits = false,
.field_runtime_bits_wip = false,
.has_namespace = ini.namespace != .none,
.any_comptime_fields = ini.any_comptime_fields,
.any_default_inits = ini.any_default_inits,
Expand Down
50 changes: 18 additions & 32 deletions src/Module.zig
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2504,6 +2504,8 @@ pub const CompileError = error{
/// In a comptime scope, a break instruction was encountered. This error is only seen when
/// evaluating a comptime block.
ComptimeBreak,
/// A dependency loop was detected when resolving if a field type has runtime bits
CircularComptimeRequirementCheck,
};

pub fn init(mod: *Module) !void {
Expand Down Expand Up @@ -4791,6 +4793,7 @@ pub fn analyzeFnBody(mod: *Module, func_index: InternPool.Index, arena: Allocato
error.GenericPoison => unreachable,
error.ComptimeReturn => unreachable,
error.ComptimeBreak => unreachable,
error.CircularComptimeRequirementCheck => unreachable,
else => |e| return e,
};
if (opt_opv) |opv| {
Expand Down Expand Up @@ -4820,10 +4823,10 @@ pub fn analyzeFnBody(mod: *Module, func_index: InternPool.Index, arena: Allocato
inner_block.error_return_trace_index = error_return_trace_index;

sema.analyzeBody(&inner_block, fn_info.body) catch |err| switch (err) {
// TODO make these unreachable instead of @panic
error.NeededSourceLocation => @panic("zig compiler bug: NeededSourceLocation"),
error.GenericPoison => @panic("zig compiler bug: GenericPoison"),
error.ComptimeReturn => @panic("zig compiler bug: ComptimeReturn"),
error.NeededSourceLocation => unreachable,
error.GenericPoison => unreachable,
error.ComptimeReturn => unreachable,
error.CircularComptimeRequirementCheck => unreachable,
else => |e| return e,
};

Expand All @@ -4845,11 +4848,11 @@ pub fn analyzeFnBody(mod: *Module, func_index: InternPool.Index, arena: Allocato
!sema.fn_ret_ty.isError(mod))
{
sema.setupErrorReturnTrace(&inner_block, last_arg_index) catch |err| switch (err) {
// TODO make these unreachable instead of @panic
error.NeededSourceLocation => @panic("zig compiler bug: NeededSourceLocation"),
error.GenericPoison => @panic("zig compiler bug: GenericPoison"),
error.ComptimeReturn => @panic("zig compiler bug: ComptimeReturn"),
error.ComptimeBreak => @panic("zig compiler bug: ComptimeBreak"),
error.NeededSourceLocation => unreachable,
error.GenericPoison => unreachable,
error.ComptimeReturn => unreachable,
error.ComptimeBreak => unreachable,
error.CircularComptimeRequirementCheck => unreachable,
else => |e| return e,
};
}
Expand Down Expand Up @@ -4877,6 +4880,7 @@ pub fn analyzeFnBody(mod: *Module, func_index: InternPool.Index, arena: Allocato
error.GenericPoison => unreachable,
error.ComptimeReturn => unreachable,
error.ComptimeBreak => unreachable,
error.CircularComptimeRequirementCheck => unreachable,
error.AnalysisFail => {
// In this case our function depends on a type that had a compile error.
// We should not try to lower this function.
Expand All @@ -4901,6 +4905,7 @@ pub fn analyzeFnBody(mod: *Module, func_index: InternPool.Index, arena: Allocato
error.GenericPoison => unreachable,
error.ComptimeReturn => unreachable,
error.ComptimeBreak => unreachable,
error.CircularComptimeRequirementCheck => unreachable,
error.AnalysisFail => {
// In this case our function depends on a type that had a compile error.
// We should not try to lower this function.
Expand All @@ -4918,6 +4923,7 @@ pub fn analyzeFnBody(mod: *Module, func_index: InternPool.Index, arena: Allocato
error.GenericPoison => unreachable,
error.ComptimeReturn => unreachable,
error.ComptimeBreak => unreachable,
error.CircularComptimeRequirementCheck => unreachable,
error.AnalysisFail => {
// In this case our function depends on a type that had a compile error.
// We should not try to lower this function.
Expand Down Expand Up @@ -6516,31 +6522,11 @@ pub fn getUnionLayout(mod: *Module, u: InternPool.UnionType) UnionLayout {
.padding = 0,
};
}
// Put the tag before or after the payload depending on which one's
// alignment is greater.

const tag_size = u.enum_tag_ty.toType().abiSize(mod);
const tag_align = u.enum_tag_ty.toType().abiAlignment(mod).max(.@"1");
var size: u64 = 0;
var padding: u32 = undefined;
if (tag_align.compare(.gte, payload_align)) {
// {Tag, Payload}
size += tag_size;
size = payload_align.forward(size);
size += payload_size;
const prev_size = size;
size = tag_align.forward(size);
padding = @intCast(size - prev_size);
} else {
// {Payload, Tag}
size += payload_size;
size = tag_align.forward(size);
size += tag_size;
const prev_size = size;
size = payload_align.forward(size);
padding = @intCast(size - prev_size);
}
return .{
.abi_size = size,
.abi_size = u.size,
.abi_align = tag_align.max(payload_align),
.most_aligned_field = most_aligned_field,
.most_aligned_field_size = most_aligned_field_size,
Expand All @@ -6549,7 +6535,7 @@ pub fn getUnionLayout(mod: *Module, u: InternPool.UnionType) UnionLayout {
.payload_align = payload_align,
.tag_align = tag_align,
.tag_size = tag_size,
.padding = padding,
.padding = u.padding,
};
}

Expand Down
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