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compiler: treat decl_val/decl_ref of potentially generic decls as captures

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This fixes an issue with the implementation of #18816. Consider the
following code:

```zig
pub fn Wrap(comptime T: type) type {
    return struct {
        pub const T1 = T;
        inner: struct { x: T1 },
    };
}
```

Previously, the type of `inner` was not considered to be "capturing" any
value, as `T1` is a decl. However, since it is declared within a generic
function, this decl reference depends on the context, and thus should be
treated as a capture.

AstGen has been augmented to tunnel references to decls through closure
when the decl was declared in a potentially-generic context (i.e. within
a function).
This commit is contained in:
mlugg
2024-03-05 07:22:47 +00:00
parent d0c022f734
commit 2c4ac44f25
6 changed files with 194 additions and 65 deletions
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116
lib/std/zig/AstGen.zig
View File

@@ -44,6 +44,9 @@ compile_errors: ArrayListUnmanaged(Zir.Inst.CompileErrors.Item) = .{},
/// The topmost block of the current function.
fn_block: ?*GenZir = null,
fn_var_args: bool = false,
/// Whether we are somewhere within a function. If `true`, any container decls may be
/// generic and thus must be tunneled through closure.
within_fn: bool = false,
/// The return type of the current function. This may be a trivial `Ref`, or
/// otherwise it refers to a `ret_type` instruction.
fn_ret_ty: Zir.Inst.Ref = .none,
@@ -4050,6 +4053,11 @@ fn fnDecl(
};
defer fn_gz.unstack();
// Set this now, since parameter types, return type, etc may be generic.
const prev_within_fn = astgen.within_fn;
defer astgen.within_fn = prev_within_fn;
astgen.within_fn = true;
const is_pub = fn_proto.visib_token != null;
const is_export = blk: {
const maybe_export_token = fn_proto.extern_export_inline_token orelse break :blk false;
@@ -4311,6 +4319,10 @@ fn fnDecl(
const prev_fn_block = astgen.fn_block;
const prev_fn_ret_ty = astgen.fn_ret_ty;
defer {
astgen.fn_block = prev_fn_block;
astgen.fn_ret_ty = prev_fn_ret_ty;
}
astgen.fn_block = &fn_gz;
astgen.fn_ret_ty = if (is_inferred_error or ret_ref.toIndex() != null) r: {
// We're essentially guaranteed to need the return type at some point,
@@ -4319,10 +4331,6 @@ fn fnDecl(
// return type now so the rest of the function can use it.
break :r try fn_gz.addNode(.ret_type, decl_node);
} else ret_ref;
defer {
astgen.fn_block = prev_fn_block;
astgen.fn_ret_ty = prev_fn_ret_ty;
}
const prev_var_args = astgen.fn_var_args;
astgen.fn_var_args = is_var_args;
@@ -4768,11 +4776,14 @@ fn testDecl(
};
defer fn_block.unstack();
const prev_within_fn = astgen.within_fn;
const prev_fn_block = astgen.fn_block;
const prev_fn_ret_ty = astgen.fn_ret_ty;
astgen.within_fn = true;
astgen.fn_block = &fn_block;
astgen.fn_ret_ty = .anyerror_void_error_union_type;
defer {
astgen.within_fn = prev_within_fn;
astgen.fn_block = prev_fn_block;
astgen.fn_ret_ty = prev_fn_ret_ty;
}
@@ -4871,6 +4882,7 @@ fn structDeclInner(
.node = node,
.inst = decl_inst,
.declaring_gz = gz,
.maybe_generic = astgen.within_fn,
};
defer namespace.deinit(gpa);
@@ -5195,6 +5207,7 @@ fn unionDeclInner(
.node = node,
.inst = decl_inst,
.declaring_gz = gz,
.maybe_generic = astgen.within_fn,
};
defer namespace.deinit(gpa);
@@ -5543,6 +5556,7 @@ fn containerDecl(
.node = node,
.inst = decl_inst,
.declaring_gz = gz,
.maybe_generic = astgen.within_fn,
};
defer namespace.deinit(gpa);
@@ -5709,6 +5723,7 @@ fn containerDecl(
.node = node,
.inst = decl_inst,
.declaring_gz = gz,
.maybe_generic = astgen.within_fn,
};
defer namespace.deinit(gpa);
@@ -8247,9 +8262,14 @@ fn localVarRef(
const name_str_index = try astgen.identAsString(ident_token);
var s = scope;
var found_already: ?Ast.Node.Index = null; // we have found a decl with the same name already
var found_needs_tunnel: bool = undefined; // defined when `found_already != null`
var found_namespaces_out: u32 = undefined; // defined when `found_already != null`
// The number of namespaces above `gz` we currently are
var num_namespaces_out: u32 = 0;
// defined when `num_namespaces_out != 0`
// defined by `num_namespaces_out != 0`
var capturing_namespace: *Scope.Namespace = undefined;
while (true) switch (s.tag) {
.local_val => {
const local_val = s.cast(Scope.LocalVal).?;
@@ -8267,9 +8287,8 @@ fn localVarRef(
gz,
ident,
num_namespaces_out,
capturing_namespace,
local_val.inst,
local_val.token_src,
.{ .ref = local_val.inst },
.{ .token = local_val.token_src },
) else local_val.inst;
return rvalueNoCoercePreRef(gz, ri, value_inst, ident);
@@ -8298,9 +8317,8 @@ fn localVarRef(
gz,
ident,
num_namespaces_out,
capturing_namespace,
local_ptr.ptr,
local_ptr.token_src,
.{ .ref = local_ptr.ptr },
.{ .token = local_ptr.token_src },
) else local_ptr.ptr;
switch (ri.rl) {
@@ -8329,6 +8347,8 @@ fn localVarRef(
}
// We found a match but must continue looking for ambiguous references to decls.
found_already = i;
found_needs_tunnel = ns.maybe_generic;
found_namespaces_out = num_namespaces_out;
}
num_namespaces_out += 1;
capturing_namespace = ns;
@@ -8343,6 +8363,29 @@ fn localVarRef(
// Decl references happen by name rather than ZIR index so that when unrelated
// decls are modified, ZIR code containing references to them can be unmodified.
if (found_namespaces_out > 0 and found_needs_tunnel) {
switch (ri.rl) {
.ref, .ref_coerced_ty => return tunnelThroughClosure(
gz,
ident,
found_namespaces_out,
.{ .decl_ref = name_str_index },
.{ .node = found_already.? },
),
else => {
const result = try tunnelThroughClosure(
gz,
ident,
found_namespaces_out,
.{ .decl_val = name_str_index },
.{ .node = found_already.? },
);
return rvalueNoCoercePreRef(gz, ri, result, ident);
},
}
}
switch (ri.rl) {
.ref, .ref_coerced_ty => return gz.addStrTok(.decl_ref, name_str_index, ident_token),
else => {
@@ -8361,17 +8404,22 @@ fn tunnelThroughClosure(
inner_ref_node: Ast.Node.Index,
/// The number of namespaces being tunnelled through. At least 1.
num_tunnels: u32,
/// The namespace being captured from.
ns: *Scope.Namespace,
/// The value being captured.
value: Zir.Inst.Ref,
/// The token of the value's declaration.
token: Ast.TokenIndex,
value: union(enum) {
ref: Zir.Inst.Ref,
decl_val: Zir.NullTerminatedString,
decl_ref: Zir.NullTerminatedString,
},
/// The location of the value's declaration.
decl_src: union(enum) {
token: Ast.TokenIndex,
node: Ast.Node.Index,
},
) !Zir.Inst.Ref {
const value_inst = value.toIndex() orelse {
// For trivial values, we don't need a tunnel; just return the ref.
return value;
};
switch (value) {
.ref => |v| if (v.toIndex() == null) return v, // trivia value; do not need tunnel
.decl_val, .decl_ref => {},
}
const astgen = gz.astgen;
const gpa = astgen.gpa;
@@ -8382,7 +8430,7 @@ fn tunnelThroughClosure(
var sfba = std.heap.stackFallback(@sizeOf(usize) * 2, astgen.arena);
var intermediate_tunnels = try sfba.get().alloc(*Scope.Namespace, num_tunnels - 1);
{
const root_ns = ns: {
var i: usize = num_tunnels - 1;
var scope: *Scope = gz.parent;
while (i > 0) {
@@ -8392,15 +8440,27 @@ fn tunnelThroughClosure(
}
scope = scope.parent().?;
}
}
while (true) {
if (scope.cast(Scope.Namespace)) |ns| break :ns ns;
scope = scope.parent().?;
}
};
// Now that we know the scopes we're tunneling through, begin adding
// captures as required, starting with the outermost namespace.
const root_capture = Zir.Inst.Capture.wrap(switch (value) {
.ref => |v| .{ .instruction = v.toIndex().? },
.decl_val => |str| .{ .decl_val = str },
.decl_ref => |str| .{ .decl_ref = str },
});
var cur_capture_index = std.math.cast(
u16,
(try ns.captures.getOrPut(gpa, Zir.Inst.Capture.wrap(.{ .inst = value_inst }))).index,
) orelse return astgen.failNodeNotes(ns.node, "this compiler implementation only supports up to 65536 captures per namespace", .{}, &.{
try astgen.errNoteTok(token, "captured value here", .{}),
(try root_ns.captures.getOrPut(gpa, root_capture)).index,
) orelse return astgen.failNodeNotes(root_ns.node, "this compiler implementation only supports up to 65536 captures per namespace", .{}, &.{
switch (decl_src) {
.token => |t| try astgen.errNoteTok(t, "captured value here", .{}),
.node => |n| try astgen.errNoteNode(n, "captured value here", .{}),
},
try astgen.errNoteNode(inner_ref_node, "value used here", .{}),
});
@@ -8409,7 +8469,10 @@ fn tunnelThroughClosure(
u16,
(try tunnel_ns.captures.getOrPut(gpa, Zir.Inst.Capture.wrap(.{ .nested = cur_capture_index }))).index,
) orelse return astgen.failNodeNotes(tunnel_ns.node, "this compiler implementation only supports up to 65536 captures per namespace", .{}, &.{
try astgen.errNoteTok(token, "captured value here", .{}),
switch (decl_src) {
.token => |t| try astgen.errNoteTok(t, "captured value here", .{}),
.node => |n| try astgen.errNoteNode(n, "captured value here", .{}),
},
try astgen.errNoteNode(inner_ref_node, "value used here", .{}),
});
}
@@ -11752,6 +11815,7 @@ const Scope = struct {
decls: std.AutoHashMapUnmanaged(Zir.NullTerminatedString, Ast.Node.Index) = .{},
node: Ast.Node.Index,
inst: Zir.Inst.Index,
maybe_generic: bool,
/// The astgen scope containing this namespace.
/// Only valid during astgen.

48
lib/std/zig/Zir.zig
View File

@@ -3057,26 +3057,50 @@ pub const Inst = struct {
};
/// Represents a single value being captured in a type declaration's closure.
/// If high bit is 0, this represents a `Zir.Inst,Index`.
/// If high bit is 1, this represents an index into the last closure.
pub const Capture = enum(u32) {
_,
pub const Capture = packed struct(u32) {
tag: enum(u2) {
/// `data` is a `u16` index into the parent closure.
nested,
/// `data` is a `Zir.Inst.Index` to an instruction whose value is being captured.
instruction,
/// `data` is a `NullTerminatedString` to a decl name.
decl_val,
/// `data` is a `NullTerminatedString` to a decl name.
decl_ref,
},
data: u30,
pub const Unwrapped = union(enum) {
inst: Zir.Inst.Index,
nested: u16,
instruction: Zir.Inst.Index,
decl_val: NullTerminatedString,
decl_ref: NullTerminatedString,
};
pub fn wrap(cap: Unwrapped) Capture {
return switch (cap) {
.inst => |inst| @enumFromInt(@intFromEnum(inst)),
.nested => |idx| @enumFromInt((1 << 31) | @as(u32, idx)),
.nested => |idx| .{
.tag = .nested,
.data = idx,
},
.instruction => |inst| .{
.tag = .instruction,
.data = @intCast(@intFromEnum(inst)),
},
.decl_val => |str| .{
.tag = .decl_val,
.data = @intCast(@intFromEnum(str)),
},
.decl_ref => |str| .{
.tag = .decl_ref,
.data = @intCast(@intFromEnum(str)),
},
};
}
pub fn unwrap(cap: Capture) Unwrapped {
const raw = @intFromEnum(cap);
const tag: u1 = @intCast(raw >> 31);
return switch (tag) {
0 => .{ .inst = @enumFromInt(raw) },
1 => .{ .nested = @truncate(raw) },
return switch (cap.tag) {
.nested => .{ .nested = @intCast(cap.data) },
.instruction => .{ .instruction = @enumFromInt(cap.data) },
.decl_val => .{ .decl_val = @enumFromInt(cap.data) },
.decl_ref => .{ .decl_ref = @enumFromInt(cap.data) },
};
}
};

22
src/Autodoc.zig
View File

@@ -459,11 +459,21 @@ const Scope = struct {
NotRequested: u32, // instr_index
};
fn getCapture(scope: Scope, idx: u16) struct { Zir.Inst.Index, *Scope } {
fn getCapture(scope: Scope, idx: u16) struct {
union(enum) { inst: Zir.Inst.Index, decl: Zir.NullTerminatedString },
*Scope,
} {
const parent = scope.parent.?;
return switch (scope.captures[idx].unwrap()) {
.inst => |inst| .{ inst, parent },
.nested => |parent_idx| parent.getCapture(parent_idx),
.instruction => |inst| .{
.{ .inst = inst },
parent,
},
.decl_val, .decl_ref => |str| .{
.{ .decl = str },
parent,
},
};
}
@@ -4048,7 +4058,13 @@ fn walkInstruction(
},
.closure_get => {
const captured, const scope = parent_scope.getCapture(extended.small);
return self.walkInstruction(file, scope, parent_src, captured, need_type, call_ctx);
switch (captured) {
.inst => |cap_inst| return self.walkInstruction(file, scope, parent_src, cap_inst, need_type, call_ctx),
.decl => |str| {
const decl_status = parent_scope.resolveDeclName(str, file, inst.toOptional());
return .{ .expr = .{ .declRef = decl_status } };
},
}
},
}
},

17
src/InternPool.zig
View File

@@ -503,22 +503,29 @@ pub const OptionalNullTerminatedString = enum(u32) {
};
/// A single value captured in the closure of a namespace type. This is not a plain
/// `Index` because we must differentiate between runtime-known values (where we
/// store the type) and comptime-known values (where we store the value).
/// `Index` because we must differentiate between the following cases:
/// * runtime-known value (where we store the type)
/// * comptime-known value (where we store the value)
/// * decl val (so that we can analyze the value lazily)
/// * decl ref (so that we can analyze the reference lazily)
pub const CaptureValue = packed struct(u32) {
tag: enum { @"comptime", runtime },
idx: u31,
tag: enum { @"comptime", runtime, decl_val, decl_ref },
idx: u30,
pub fn wrap(val: Unwrapped) CaptureValue {
return switch (val) {
.@"comptime" => |i| .{ .tag = .@"comptime", .idx = @intCast(@intFromEnum(i)) },
.runtime => |i| .{ .tag = .runtime, .idx = @intCast(@intFromEnum(i)) },
.decl_val => |i| .{ .tag = .decl_val, .idx = @intCast(@intFromEnum(i)) },
.decl_ref => |i| .{ .tag = .decl_ref, .idx = @intCast(@intFromEnum(i)) },
};
}
pub fn unwrap(val: CaptureValue) Unwrapped {
return switch (val.tag) {
.@"comptime" => .{ .@"comptime" = @enumFromInt(val.idx) },
.runtime => .{ .runtime = @enumFromInt(val.idx) },
.decl_val => .{ .decl_val = @enumFromInt(val.idx) },
.decl_ref => .{ .decl_ref = @enumFromInt(val.idx) },
};
}
@@ -527,6 +534,8 @@ pub const CaptureValue = packed struct(u32) {
@"comptime": Index,
/// Index refers to the type.
runtime: Index,
decl_val: DeclIndex,
decl_ref: DeclIndex,
};
pub const Slice = struct {

32
src/Sema.zig
View File

@@ -2671,26 +2671,34 @@ fn analyzeAsInt(
/// Given a ZIR extra index which points to a list of `Zir.Inst.Capture`,
/// resolves this into a list of `InternPool.CaptureValue` allocated by `arena`.
fn getCaptures(sema: *Sema, parent_namespace: ?InternPool.NamespaceIndex, extra_index: usize, captures_len: u32) ![]InternPool.CaptureValue {
fn getCaptures(sema: *Sema, block: *Block, extra_index: usize, captures_len: u32) ![]InternPool.CaptureValue {
const zcu = sema.mod;
const ip = &zcu.intern_pool;
const parent_captures: InternPool.CaptureValue.Slice = if (parent_namespace) |p| parent: {
break :parent zcu.namespacePtr(p).ty.getCaptures(zcu);
} else undefined; // never used so `undefined` is safe
const parent_captures: InternPool.CaptureValue.Slice = zcu.namespacePtr(block.namespace).ty.getCaptures(zcu);
const captures = try sema.arena.alloc(InternPool.CaptureValue, captures_len);
for (sema.code.extra[extra_index..][0..captures_len], captures) |raw, *capture| {
const zir_capture: Zir.Inst.Capture = @enumFromInt(raw);
const zir_capture: Zir.Inst.Capture = @bitCast(raw);
capture.* = switch (zir_capture.unwrap()) {
.inst => |inst| InternPool.CaptureValue.wrap(capture: {
.nested => |parent_idx| parent_captures.get(ip)[parent_idx],
.instruction => |inst| InternPool.CaptureValue.wrap(capture: {
const air_ref = try sema.resolveInst(inst.toRef());
if (try sema.resolveValueResolveLazy(air_ref)) |val| {
break :capture .{ .@"comptime" = val.toIntern() };
}
break :capture .{ .runtime = sema.typeOf(air_ref).toIntern() };
}),
.nested => |parent_idx| parent_captures.get(ip)[parent_idx],
.decl_val => |str| capture: {
const decl_name = try ip.getOrPutString(sema.gpa, sema.code.nullTerminatedString(str));
const decl = try sema.lookupIdentifier(block, .unneeded, decl_name); // TODO: could we need this src loc?
break :capture InternPool.CaptureValue.wrap(.{ .decl_val = decl });
},
.decl_ref => |str| capture: {
const decl_name = try ip.getOrPutString(sema.gpa, sema.code.nullTerminatedString(str));
const decl = try sema.lookupIdentifier(block, .unneeded, decl_name); // TODO: could we need this src loc?
break :capture InternPool.CaptureValue.wrap(.{ .decl_ref = decl });
},
};
}
@@ -2727,7 +2735,7 @@ fn zirStructDecl(
break :blk decls_len;
} else 0;
const captures = try sema.getCaptures(block.namespace, extra_index, captures_len);
const captures = try sema.getCaptures(block, extra_index, captures_len);
extra_index += captures_len;
if (small.has_backing_int) {
@@ -2944,7 +2952,7 @@ fn zirEnumDecl(
break :blk decls_len;
} else 0;
const captures = try sema.getCaptures(block.namespace, extra_index, captures_len);
const captures = try sema.getCaptures(block, extra_index, captures_len);
extra_index += captures_len;
const decls = sema.code.bodySlice(extra_index, decls_len);
@@ -3209,7 +3217,7 @@ fn zirUnionDecl(
break :blk decls_len;
} else 0;
const captures = try sema.getCaptures(block.namespace, extra_index, captures_len);
const captures = try sema.getCaptures(block, extra_index, captures_len);
extra_index += captures_len;
const wip_ty = switch (try ip.getUnionType(gpa, .{
@@ -3315,7 +3323,7 @@ fn zirOpaqueDecl(
break :blk decls_len;
} else 0;
const captures = try sema.getCaptures(block.namespace, extra_index, captures_len);
const captures = try sema.getCaptures(block, extra_index, captures_len);
extra_index += captures_len;
const wip_ty = switch (try ip.getOpaqueType(gpa, .{
@@ -17268,6 +17276,8 @@ fn zirClosureGet(sema: *Sema, block: *Block, extended: Zir.Inst.Extended.InstDat
const capture_ty = switch (captures.get(ip)[extended.small].unwrap()) {
.@"comptime" => |index| return Air.internedToRef(index),
.runtime => |index| index,
.decl_val => |decl_index| return sema.analyzeDeclVal(block, src, decl_index),
.decl_ref => |decl_index| return sema.analyzeDeclRef(decl_index),
};
// The comptime case is handled already above. Runtime case below.

24
src/print_zir.zig
View File

@@ -1427,11 +1427,11 @@ const Writer = struct {
try stream.writeAll("{}, ");
} else {
try stream.writeAll("{ ");
try self.writeCapture(stream, @enumFromInt(self.code.extra[extra_index]));
try self.writeCapture(stream, @bitCast(self.code.extra[extra_index]));
extra_index += 1;
for (1..captures_len) |_| {
try stream.writeAll(", ");
try self.writeCapture(stream, @enumFromInt(self.code.extra[extra_index]));
try self.writeCapture(stream, @bitCast(self.code.extra[extra_index]));
extra_index += 1;
}
try stream.writeAll(" }, ");
@@ -1652,11 +1652,11 @@ const Writer = struct {
try stream.writeAll("{}, ");
} else {
try stream.writeAll("{ ");
try self.writeCapture(stream, @enumFromInt(self.code.extra[extra_index]));
try self.writeCapture(stream, @bitCast(self.code.extra[extra_index]));
extra_index += 1;
for (1..captures_len) |_| {
try stream.writeAll(", ");
try self.writeCapture(stream, @enumFromInt(self.code.extra[extra_index]));
try self.writeCapture(stream, @bitCast(self.code.extra[extra_index]));
extra_index += 1;
}
try stream.writeAll(" }, ");
@@ -1817,11 +1817,11 @@ const Writer = struct {
try stream.writeAll("{}, ");
} else {
try stream.writeAll("{ ");
try self.writeCapture(stream, @enumFromInt(self.code.extra[extra_index]));
try self.writeCapture(stream, @bitCast(self.code.extra[extra_index]));
extra_index += 1;
for (1..captures_len) |_| {
try stream.writeAll(", ");
try self.writeCapture(stream, @enumFromInt(self.code.extra[extra_index]));
try self.writeCapture(stream, @bitCast(self.code.extra[extra_index]));
extra_index += 1;
}
try stream.writeAll(" }, ");
@@ -1930,11 +1930,11 @@ const Writer = struct {
try stream.writeAll("{}, ");
} else {
try stream.writeAll("{ ");
try self.writeCapture(stream, @enumFromInt(self.code.extra[extra_index]));
try self.writeCapture(stream, @bitCast(self.code.extra[extra_index]));
extra_index += 1;
for (1..captures_len) |_| {
try stream.writeAll(", ");
try self.writeCapture(stream, @enumFromInt(self.code.extra[extra_index]));
try self.writeCapture(stream, @bitCast(self.code.extra[extra_index]));
extra_index += 1;
}
try stream.writeAll(" }, ");
@@ -2808,8 +2808,14 @@ const Writer = struct {
fn writeCapture(self: *Writer, stream: anytype, capture: Zir.Inst.Capture) !void {
switch (capture.unwrap()) {
.inst => |inst| return self.writeInstIndex(stream, inst),
.nested => |i| return stream.print("[{d}]", .{i}),
.instruction => |inst| return self.writeInstIndex(stream, inst),
.decl_val => |str| try stream.print("decl_val \"{}\"", .{
std.zig.fmtEscapes(self.code.nullTerminatedString(str)),
}),
.decl_ref => |str| try stream.print("decl_ref \"{}\"", .{
std.zig.fmtEscapes(self.code.nullTerminatedString(str)),
}),
}
}