zig

commit c4a2734aa08a9e810680d7be2c976fe3ae67cc5b (tree)
parent aa2aad229c96427f8b9130a3665a1f6ad768ec4c
Author: Andrew Kelley <andrew@ziglang.org>
Date:   Wed, 26 Feb 2020 11:11:28 -0500

Merge pull request #4561 from LemonBoy/fix-4536-1

Resend of #4552
Diffstat:
M
src/analyze.cpp
 | 
20
++++++++++++++------
M
test/stage1/behavior/sizeof_and_typeof.zig
 | 
56
++++++++++++++++++++++++++++++++++++++++++++++++++++++--

2 files changed, 68 insertions(+), 8 deletions(-)
diff --git a/src/analyze.cpp b/src/analyze.cpp
@@ -1131,18 +1131,26 @@ Error type_val_resolve_zero_bits(CodeGen *g, ZigValue *type_val, ZigType *parent
     Error err;
     if (type_val->special != ConstValSpecialLazy) {
         assert(type_val->special == ConstValSpecialStatic);
-        if ((type_val->data.x_type->id == ZigTypeIdStruct &&
-            type_val->data.x_type->data.structure.resolve_loop_flag_zero_bits) ||
-            (type_val->data.x_type->id == ZigTypeIdUnion &&
-             type_val->data.x_type->data.unionation.resolve_loop_flag_zero_bits) ||
-            type_val->data.x_type->id == ZigTypeIdPointer)
+
+        // Self-referencing types via pointers are allowed and have non-zero size
+        ZigType *ty = type_val->data.x_type;
+        while (ty->id == ZigTypeIdPointer &&
+               !ty->data.unionation.resolve_loop_flag_zero_bits)
+        {
+            ty = ty->data.pointer.child_type;
+        }
+
+        if ((ty->id == ZigTypeIdStruct && ty->data.structure.resolve_loop_flag_zero_bits) ||
+            (ty->id == ZigTypeIdUnion && ty->data.unionation.resolve_loop_flag_zero_bits) ||
+            (ty->id == ZigTypeIdPointer && ty->data.pointer.resolve_loop_flag_zero_bits))
         {
-            // Does a struct/union which contains a pointer field to itself have bits? Yes.
             *is_zero_bits = false;
             return ErrorNone;
         }
+
         if ((err = type_resolve(g, type_val->data.x_type, ResolveStatusZeroBitsKnown)))
             return err;
+
         *is_zero_bits = (type_val->data.x_type->abi_size == 0);
         return ErrorNone;
     }
diff --git a/test/stage1/behavior/sizeof_and_typeof.zig b/test/stage1/behavior/sizeof_and_typeof.zig
@@ -1,5 +1,7 @@
-const builtin = @import("builtin");
-const expect = @import("std").testing.expect;
+const std = @import("std");
+const builtin = std.builtin;
+const expect = std.testing.expect;
+const expectEqual = std.testing.expectEqual;
 
 test "@sizeOf and @TypeOf" {
     const y: @TypeOf(x) = 120;
@@ -135,3 +137,53 @@ test "@bitSizeOf" {
         a: u2
     }) == 2);
 }
+
+test "@sizeOf comparison against zero" {
+    const S0 = struct {
+        f: *@This(),
+    };
+    const U0 = union {
+        f: *@This(),
+    };
+    const S1 = struct {
+        fn H(comptime T: type) type {
+            return struct {
+                x: T,
+            };
+        }
+        f0: H(*@This()),
+        f1: H(**@This()),
+        f2: H(***@This()),
+    };
+    const U1 = union {
+        fn H(comptime T: type) type {
+            return struct {
+                x: T,
+            };
+        }
+        f0: H(*@This()),
+        f1: H(**@This()),
+        f2: H(***@This()),
+    };
+    const S = struct {
+        fn doTheTest(comptime T: type, comptime result: bool) void {
+            expectEqual(result, @sizeOf(T) > 0);
+        }
+    };
+    // Zero-sized type
+    S.doTheTest(u0, false);
+    S.doTheTest(*u0, false);
+    // Non byte-sized type
+    S.doTheTest(u1, true);
+    S.doTheTest(*u1, true);
+    // Regular type
+    S.doTheTest(u8, true);
+    S.doTheTest(*u8, true);
+    S.doTheTest(f32, true);
+    S.doTheTest(*f32, true);
+    // Container with ptr pointing to themselves
+    S.doTheTest(S0, true);
+    S.doTheTest(U0, true);
+    S.doTheTest(S1, true);
+    S.doTheTest(U1, true);
+}