Commit 81b5df347a

Andrew Kelley <andrew@ziglang.org>
2023-09-22 02:29:34
compiler: fix structFieldName crash for tuples
When struct types have no field names, the names are implicitly understood to be strings corresponding to the field indexes in declaration order. It used to be the case that a NullTerminatedString would be stored for each field in this case, however, now, callers must handle the possibility that there are no names stored at all. This commit introduces `legacyStructFieldName`, a function to fake the previous behavior. Probably something better could be done by reworking all the callsites of this function.
1 parent edfada4
src/codegen/c/type.zig
@@ -1953,7 +1953,8 @@ pub const CType = extern union {
 
                     const fields_pl = try arena.alloc(Payload.Fields.Field, c_fields_len);
                     var c_field_i: usize = 0;
-                    for (0..fields_len) |field_i| {
+                    for (0..fields_len) |field_i_usize| {
+                        const field_i: u32 = @intCast(field_i_usize);
                         const field_ty = ty.structFieldType(field_i, mod);
                         if ((zig_ty_tag == .Struct and ty.structFieldIsComptime(field_i, mod)) or
                             !field_ty.hasRuntimeBitsIgnoreComptime(mod)) continue;
@@ -1964,7 +1965,7 @@ pub const CType = extern union {
                                 std.fmt.allocPrintZ(arena, "f{}", .{field_i})
                             else
                                 arena.dupeZ(u8, ip.stringToSlice(switch (zig_ty_tag) {
-                                    .Struct => ty.structFieldName(field_i, mod),
+                                    .Struct => ty.legacyStructFieldName(field_i, mod),
                                     .Union => mod.typeToUnion(ty).?.field_names.get(ip)[field_i],
                                     else => unreachable,
                                 })),
@@ -2097,7 +2098,8 @@ pub const CType = extern union {
                                 .Struct => ty.structFieldCount(mod),
                                 .Union => mod.typeToUnion(ty).?.field_names.len,
                                 else => unreachable,
-                            }) |field_i| {
+                            }) |field_i_usize| {
+                                const field_i: u32 = @intCast(field_i_usize);
                                 const field_ty = ty.structFieldType(field_i, mod);
                                 if ((zig_ty_tag == .Struct and ty.structFieldIsComptime(field_i, mod)) or
                                     !field_ty.hasRuntimeBitsIgnoreComptime(mod)) continue;
@@ -2116,7 +2118,7 @@ pub const CType = extern union {
                                         std.fmt.bufPrintZ(&name_buf, "f{}", .{field_i}) catch unreachable
                                     else
                                         ip.stringToSlice(switch (zig_ty_tag) {
-                                            .Struct => ty.structFieldName(field_i, mod),
+                                            .Struct => ty.legacyStructFieldName(field_i, mod),
                                             .Union => mod.typeToUnion(ty).?.field_names.get(ip)[field_i],
                                             else => unreachable,
                                         }),
@@ -2225,7 +2227,8 @@ pub const CType = extern union {
                                 .Struct => ty.structFieldCount(mod),
                                 .Union => mod.typeToUnion(ty).?.field_names.len,
                                 else => unreachable,
-                            }) |field_i| {
+                            }) |field_i_usize| {
+                                const field_i: u32 = @intCast(field_i_usize);
                                 const field_ty = ty.structFieldType(field_i, mod);
                                 if ((zig_ty_tag == .Struct and ty.structFieldIsComptime(field_i, mod)) or
                                     !field_ty.hasRuntimeBitsIgnoreComptime(mod)) continue;
@@ -2240,7 +2243,7 @@ pub const CType = extern union {
                                     std.fmt.bufPrint(&name_buf, "f{}", .{field_i}) catch unreachable
                                 else
                                     mod.intern_pool.stringToSlice(switch (zig_ty_tag) {
-                                        .Struct => ty.structFieldName(field_i, mod),
+                                        .Struct => ty.legacyStructFieldName(field_i, mod),
                                         .Union => mod.typeToUnion(ty).?.field_names.get(ip)[field_i],
                                         else => unreachable,
                                     }));
src/codegen/c.zig
@@ -5226,7 +5226,8 @@ fn fieldLocation(
     const container_ty = container_ptr_ty.childType(mod);
     return switch (container_ty.zigTypeTag(mod)) {
         .Struct => switch (container_ty.containerLayout(mod)) {
-            .Auto, .Extern => for (field_index..container_ty.structFieldCount(mod)) |next_field_index| {
+            .Auto, .Extern => for (field_index..container_ty.structFieldCount(mod)) |next_field_index_usize| {
+                const next_field_index: u32 = @intCast(next_field_index_usize);
                 if (container_ty.structFieldIsComptime(next_field_index, mod)) continue;
                 const field_ty = container_ty.structFieldType(next_field_index, mod);
                 if (!field_ty.hasRuntimeBitsIgnoreComptime(mod)) continue;
@@ -5234,7 +5235,7 @@ fn fieldLocation(
                 break .{ .field = if (container_ty.isSimpleTuple(mod))
                     .{ .field = next_field_index }
                 else
-                    .{ .identifier = ip.stringToSlice(container_ty.structFieldName(next_field_index, mod)) } };
+                    .{ .identifier = ip.stringToSlice(container_ty.legacyStructFieldName(next_field_index, mod)) } };
             } else if (container_ty.hasRuntimeBitsIgnoreComptime(mod)) .end else .begin,
             .Packed => if (field_ptr_ty.ptrInfo(mod).packed_offset.host_size == 0)
                 .{ .byte_offset = container_ty.packedStructFieldByteOffset(field_index, mod) + @divExact(container_ptr_ty.ptrInfo(mod).packed_offset.bit_offset, 8) }
@@ -5421,7 +5422,7 @@ fn airStructFieldVal(f: *Function, inst: Air.Inst.Index) !CValue {
             .Auto, .Extern => if (struct_ty.isSimpleTuple(mod))
                 .{ .field = extra.field_index }
             else
-                .{ .identifier = ip.stringToSlice(struct_ty.structFieldName(extra.field_index, mod)) },
+                .{ .identifier = ip.stringToSlice(struct_ty.legacyStructFieldName(extra.field_index, mod)) },
             .Packed => {
                 const struct_type = mod.typeToStruct(struct_ty).?;
                 const int_info = struct_ty.intInfo(mod);
@@ -5483,7 +5484,7 @@ fn airStructFieldVal(f: *Function, inst: Air.Inst.Index) !CValue {
         .anon_struct_type => |anon_struct_type| if (anon_struct_type.names.len == 0)
             .{ .field = extra.field_index }
         else
-            .{ .identifier = ip.stringToSlice(struct_ty.structFieldName(extra.field_index, mod)) },
+            .{ .identifier = ip.stringToSlice(struct_ty.legacyStructFieldName(extra.field_index, mod)) },
 
         .union_type => |union_type| field_name: {
             const union_obj = ip.loadUnionType(union_type);
@@ -6816,7 +6817,8 @@ fn airAggregateInit(f: *Function, inst: Air.Inst.Index) !CValue {
             }
         },
         .Struct => switch (inst_ty.containerLayout(mod)) {
-            .Auto, .Extern => for (resolved_elements, 0..) |element, field_i| {
+            .Auto, .Extern => for (resolved_elements, 0..) |element, field_i_usize| {
+                const field_i: u32 = @intCast(field_i_usize);
                 if (inst_ty.structFieldIsComptime(field_i, mod)) continue;
                 const field_ty = inst_ty.structFieldType(field_i, mod);
                 if (!field_ty.hasRuntimeBitsIgnoreComptime(mod)) continue;
@@ -6825,7 +6827,7 @@ fn airAggregateInit(f: *Function, inst: Air.Inst.Index) !CValue {
                 try f.writeCValueMember(writer, local, if (inst_ty.isSimpleTuple(mod))
                     .{ .field = field_i }
                 else
-                    .{ .identifier = ip.stringToSlice(inst_ty.structFieldName(field_i, mod)) });
+                    .{ .identifier = ip.stringToSlice(inst_ty.legacyStructFieldName(field_i, mod)) });
                 try a.assign(f, writer);
                 try f.writeCValue(writer, element, .Other);
                 try a.end(f, writer);
src/InternPool.zig
@@ -656,6 +656,17 @@ pub const Key = union(enum) {
         pub fn isTuple(self: AnonStructType) bool {
             return self.names.len == 0;
         }
+
+        pub fn fieldName(
+            self: AnonStructType,
+            ip: *const InternPool,
+            index: u32,
+        ) OptionalNullTerminatedString {
+            if (self.names.len == 0)
+                return .none;
+
+            return self.names.get(ip)[index].toOptional();
+        }
     };
 
     /// Serves two purposes:
src/Sema.zig
@@ -4699,12 +4699,13 @@ fn validateStructInit(
         // In this case the only thing we need to do is evaluate the implicit
         // store instructions for default field values, and report any missing fields.
         // Avoid the cost of the extra machinery for detecting a comptime struct init value.
-        for (found_fields, 0..) |field_ptr, i| {
+        for (found_fields, 0..) |field_ptr, i_usize| {
+            const i: u32 = @intCast(i_usize);
             if (field_ptr != 0) continue;
 
             const default_val = struct_ty.structFieldDefaultValue(i, mod);
             if (default_val.toIntern() == .unreachable_value) {
-                if (struct_ty.isTuple(mod)) {
+                const field_name = struct_ty.structFieldName(i, mod).unwrap() orelse {
                     const template = "missing tuple field with index {d}";
                     if (root_msg) |msg| {
                         try sema.errNote(block, init_src, msg, template, .{i});
@@ -4712,8 +4713,7 @@ fn validateStructInit(
                         root_msg = try sema.errMsg(block, init_src, template, .{i});
                     }
                     continue;
-                }
-                const field_name = struct_ty.structFieldName(i, mod);
+                };
                 const template = "missing struct field: {}";
                 const args = .{field_name.fmt(ip)};
                 if (root_msg) |msg| {
@@ -4763,7 +4763,8 @@ fn validateStructInit(
     // ends up being comptime-known.
     const field_values = try sema.arena.alloc(InternPool.Index, struct_ty.structFieldCount(mod));
 
-    field: for (found_fields, 0..) |field_ptr, i| {
+    field: for (found_fields, 0..) |field_ptr, i_usize| {
+        const i: u32 = @intCast(i_usize);
         if (field_ptr != 0) {
             // Determine whether the value stored to this pointer is comptime-known.
             const field_ty = struct_ty.structFieldType(i, mod);
@@ -4842,7 +4843,7 @@ fn validateStructInit(
 
         const default_val = struct_ty.structFieldDefaultValue(i, mod);
         if (default_val.toIntern() == .unreachable_value) {
-            if (struct_ty.isTuple(mod)) {
+            const field_name = struct_ty.structFieldName(i, mod).unwrap() orelse {
                 const template = "missing tuple field with index {d}";
                 if (root_msg) |msg| {
                     try sema.errNote(block, init_src, msg, template, .{i});
@@ -4850,8 +4851,7 @@ fn validateStructInit(
                     root_msg = try sema.errMsg(block, init_src, template, .{i});
                 }
                 continue;
-            }
-            const field_name = struct_ty.structFieldName(i, mod);
+            };
             const template = "missing struct field: {}";
             const args = .{field_name.fmt(ip)};
             if (root_msg) |msg| {
@@ -21862,10 +21862,10 @@ fn ptrCastFull(
                 const msg = try sema.errMsg(block, src, "cast increases pointer alignment", .{});
                 errdefer msg.destroy(sema.gpa);
                 try sema.errNote(block, operand_src, msg, "'{}' has alignment '{d}'", .{
-                    operand_ty.fmt(mod), src_align,
+                    operand_ty.fmt(mod), src_align.toByteUnits(0),
                 });
                 try sema.errNote(block, src, msg, "'{}' has alignment '{d}'", .{
-                    dest_ty.fmt(mod), dest_align,
+                    dest_ty.fmt(mod), dest_align.toByteUnits(0),
                 });
                 try sema.errNote(block, src, msg, "use @alignCast to assert pointer alignment", .{});
                 break :msg msg;
@@ -26376,7 +26376,7 @@ fn fieldCallBind(
                     const max = concrete_ty.structFieldCount(mod);
                     for (0..max) |i_usize| {
                         const i: u32 = @intCast(i_usize);
-                        if (field_name == concrete_ty.structFieldName(i, mod)) {
+                        if (field_name == concrete_ty.structFieldName(i, mod).unwrap().?) {
                             return sema.finishFieldCallBind(block, src, ptr_ty, concrete_ty.structFieldType(i, mod), i, object_ptr);
                         }
                     }
@@ -31143,7 +31143,8 @@ fn coerceTupleToTuple(
     var root_msg: ?*Module.ErrorMsg = null;
     errdefer if (root_msg) |msg| msg.destroy(sema.gpa);
 
-    for (field_refs, 0..) |*field_ref, i| {
+    for (field_refs, 0..) |*field_ref, i_usize| {
+        const i: u32 = @intCast(i_usize);
         if (field_ref.* != .none) continue;
 
         const default_val = switch (ip.indexToKey(tuple_ty.toIntern())) {
@@ -31154,7 +31155,7 @@ fn coerceTupleToTuple(
 
         const field_src = inst_src; // TODO better source location
         if (default_val == .none) {
-            if (tuple_ty.isTuple(mod)) {
+            const field_name = tuple_ty.structFieldName(i, mod).unwrap() orelse {
                 const template = "missing tuple field: {d}";
                 if (root_msg) |msg| {
                     try sema.errNote(block, field_src, msg, template, .{i});
@@ -31162,9 +31163,9 @@ fn coerceTupleToTuple(
                     root_msg = try sema.errMsg(block, field_src, template, .{i});
                 }
                 continue;
-            }
+            };
             const template = "missing struct field: {}";
-            const args = .{tuple_ty.structFieldName(i, mod).fmt(ip)};
+            const args = .{field_name.fmt(ip)};
             if (root_msg) |msg| {
                 try sema.errNote(block, field_src, msg, template, args);
             } else {
@@ -33897,8 +33898,9 @@ fn resolvePeerTypesInner(
                 }
 
                 if (!is_tuple) {
-                    for (field_names, 0..) |expected, field_idx| {
-                        const actual = ty.structFieldName(field_idx, mod);
+                    for (field_names, 0..) |expected, field_index_usize| {
+                        const field_index: u32 = @intCast(field_index_usize);
+                        const actual = ty.structFieldName(field_index, mod).unwrap().?;
                         if (actual == expected) continue;
                         return .{ .conflict = .{
                             .peer_idx_a = first_idx,
src/type.zig
@@ -2907,16 +2907,28 @@ pub const Type = struct {
         return enum_type.tagValueIndex(ip, int_tag);
     }
 
-    pub fn structFieldName(ty: Type, field_index: usize, mod: *Module) InternPool.NullTerminatedString {
+    /// Returns none in the case of a tuple which uses the integer index as the field name.
+    pub fn structFieldName(ty: Type, field_index: u32, mod: *Module) InternPool.OptionalNullTerminatedString {
         const ip = &mod.intern_pool;
         return switch (ip.indexToKey(ty.toIntern())) {
-            .struct_type => |struct_type| struct_type.field_names.get(ip)[field_index],
-            .anon_struct_type => |anon_struct| anon_struct.names.get(ip)[field_index],
+            .struct_type => |struct_type| struct_type.fieldName(ip, field_index),
+            .anon_struct_type => |anon_struct| anon_struct.fieldName(ip, field_index),
             else => unreachable,
         };
     }
 
-    pub fn structFieldCount(ty: Type, mod: *Module) usize {
+    /// When struct types have no field names, the names are implicitly understood to be
+    /// strings corresponding to the field indexes in declaration order. It used to be the
+    /// case that a NullTerminatedString would be stored for each field in this case, however,
+    /// now, callers must handle the possibility that there are no names stored at all.
+    /// Here we fake the previous behavior. Probably something better could be done by examining
+    /// all the callsites of this function.
+    pub fn legacyStructFieldName(ty: Type, i: u32, mod: *Module) InternPool.NullTerminatedString {
+        return ty.structFieldName(i, mod).unwrap() orelse
+            mod.intern_pool.getOrPutStringFmt(mod.gpa, "{d}", .{i}) catch @panic("OOM");
+    }
+
+    pub fn structFieldCount(ty: Type, mod: *Module) u32 {
         const ip = &mod.intern_pool;
         return switch (ip.indexToKey(ty.toIntern())) {
             .struct_type => |struct_type| struct_type.field_types.len,
src/TypedValue.zig
@@ -355,11 +355,11 @@ pub fn print(
                         const container_ty = ptr_container_ty.childType(mod);
                         switch (container_ty.zigTypeTag(mod)) {
                             .Struct => {
-                                if (container_ty.isTuple(mod)) {
+                                if (container_ty.structFieldName(@intCast(field.index), mod).unwrap()) |field_name| {
+                                    try writer.print(".{i}", .{field_name.fmt(ip)});
+                                } else {
                                     try writer.print("[{d}]", .{field.index});
                                 }
-                                const field_name = container_ty.structFieldName(@as(usize, @intCast(field.index)), mod);
-                                try writer.print(".{i}", .{field_name.fmt(ip)});
                             },
                             .Union => {
                                 const field_name = mod.typeToUnion(container_ty).?.field_names.get(ip)[@intCast(field.index)];