Commit 4fccc95b0152aefeb40912768ec045b57a2fdc2b | zig

author	Andrew Kelley <andrew@ziglang.org> 2022-01-20 15:36:40-07:00
committer	Andrew Kelley <andrew@ziglang.org> 2022-01-20 16:17:16-07:00
log	4fccc95b0152aefeb40912768ec045b57a2fdc2b
tree	711ec4766c0cd236b239eb448398d2162c770068
parent	e86ff712a666ab5be54fa763cc12a5f245718117

Sema: fix requiresComptime infinite recursion

When asking a struct or union whether the type requires comptime, it may
need to ask itself recursively, for example because of a field which is
a pointer to itself. This commit adds a field to each to keep track of
when computing the "requires comptime" value and returns `false` if the
check is already ongoing.

2 files changed, 37 insertions(+), 11 deletions(-)

src
- Module.zig
- type.zig

src/Module.zig+4

...	@@ -821,6 +821,8 @@ pub const ErrorSet = struct {	...	@@ -821,6 +821,8 @@ pub const ErrorSet = struct {
821	}	821	}
822	};	822	};
823		823
		824	pub const RequiresComptime = enum { no, yes, unknown, wip };
		825
824	/// Represents the data that a struct declaration provides.	826	/// Represents the data that a struct declaration provides.
825	pub const Struct = struct {	827	pub const Struct = struct {
826	/// The Decl that corresponds to the struct itself.	828	/// The Decl that corresponds to the struct itself.
...	@@ -849,6 +851,7 @@ pub const Struct = struct {	...	@@ -849,6 +851,7 @@ pub const Struct = struct {
849	/// If true, definitely nonzero size at runtime. If false, resolving the fields	851	/// If true, definitely nonzero size at runtime. If false, resolving the fields
850	/// is necessary to determine whether it has bits at runtime.	852	/// is necessary to determine whether it has bits at runtime.
851	known_has_bits: bool,	853	known_has_bits: bool,
		854	requires_comptime: RequiresComptime = .unknown,
852		855
853	pub const Fields = std.StringArrayHashMapUnmanaged(Field);	856	pub const Fields = std.StringArrayHashMapUnmanaged(Field);
854		857
...	@@ -1038,6 +1041,7 @@ pub const Union = struct {	...	@@ -1038,6 +1041,7 @@ pub const Union = struct {
1038	// which `have_layout` does not ensure.	1041	// which `have_layout` does not ensure.
1039	fully_resolved,	1042	fully_resolved,
1040	},	1043	},
		1044	requires_comptime: RequiresComptime = .unknown,
1041		1045
1042	pub const Field = struct {	1046	pub const Field = struct {
1043	/// undefined until `status` is `have_field_types` or `have_layout`.	1047	/// undefined until `status` is `have_field_types` or `have_layout`.

src/type.zig+33-11

 @@ -1544,22 +1544,40 @@ pub const Type = extern union {
             .@"struct" => {
                 const struct_obj = ty.castTag(.@"struct").?.data;
-                for (struct_obj.fields.values()) |field| {
+                switch (struct_obj.requires_comptime) {
-                    if (requiresComptime(field.ty)) {
+                    .no, .wip => return false,
-                        return true;
+                    .yes => return true,
-                    }
+                    .unknown => {
+                        struct_obj.requires_comptime = .wip;
+                        for (struct_obj.fields.values()) |field| {
+                            if (requiresComptime(field.ty)) {
+                                struct_obj.requires_comptime = .yes;
+                                return true;
+                            }
+                        }
+                        struct_obj.requires_comptime = .no;
+                        return false;
+                    },
                 }
-                return false;
             },
             .@"union", .union_tagged => {
                 const union_obj = ty.cast(Payload.Union).?.data;
-                for (union_obj.fields.values()) |field| {
+                switch (union_obj.requires_comptime) {
-                    if (requiresComptime(field.ty)) {
+                    .no, .wip => return false,
-                        return true;
+                    .yes => return true,
-                    }
+                    .unknown => {
+                        union_obj.requires_comptime = .wip;
+                        for (union_obj.fields.values()) |field| {
+                            if (requiresComptime(field.ty)) {
+                                union_obj.requires_comptime = .yes;
+                                return true;
+                            }
+                        }
+                        union_obj.requires_comptime = .no;
+                        return false;
+                    },
                 }
-                return false;
             },
             .error_union => return requiresComptime(errorUnionPayload(ty)),
 @@ -3661,7 +3679,7 @@ pub const Type = extern union {
                 .Slice, .Many, .C => true,
                 .One => ty.elemType().zigTypeTag() == .Array,
             },
-            .Struct => ty.tag() == .tuple,
+            .Struct => ty.isTuple(),
             else => false,
         };
     }
 @@ -4501,6 +4519,10 @@ pub const Type = extern union {
         }
     };
+    pub fn isTuple(ty: Type) bool {
+        return ty.tag() == .tuple;
+    }
     /// The sub-types are named after what fields they contain.
     pub const Payload = struct {
         tag: Tag,