Commit e2a9f2ef988e6ff4ec9f943ead9285c67c56ffd7 | zig

author	raulgrell <raulgrell@gmail.com> 2018-08-27 16:37:37+01:00
committer	raulgrell <raulgrell@gmail.com> 2018-08-27 23:13:57+01:00
log	e2a9f2ef988e6ff4ec9f943ead9285c67c56ffd7
tree	b61d37c78a9281d55959af5bf6de6d6a5412087a
parent	c48be3a742cd82a8007512bfe145374e4b3750be

Allow implicit cast from T and []T to ?*c_void

2 files changed, 40 insertions(+), 4 deletions(-)

src
- ir.cpp
test
- cases
  - cast.zig

src/ir.cpp+16-4

 @@ -60,7 +60,7 @@ enum ConstCastResultId {
     ConstCastResultIdType,
     ConstCastResultIdUnresolvedInferredErrSet,
     ConstCastResultIdAsyncAllocatorType,
-    ConstCastResultIdNullWrapPtr,
+    ConstCastResultIdNullWrapPtr
 };
 struct ConstCastOnly;
 @@ -8471,9 +8471,9 @@ static ConstCastOnly types_match_const_cast_only(IrAnalyze *ira, TypeTableEntry
     if (wanted_type == actual_type)
         return result;
-    // * and [*] can do a const-cast-only to ?* and ?[*], respectively
+    // *T and [*]T may const-cast-only to ?*U and ?[*]U, respectively
-    // but not if there is a mutable parent pointer
+    // but not if we want a mutable pointer
-    // and not if the pointer is zero bits
+    // and not if the actual pointer has zero bits
     if (!wanted_is_mutable && wanted_type->id == TypeTableEntryIdOptional &&
         wanted_type->data.maybe.child_type->id == TypeTableEntryIdPointer &&
         actual_type->id == TypeTableEntryIdPointer && type_has_bits(actual_type))
 @@ -8488,6 +8488,18 @@ static ConstCastOnly types_match_const_cast_only(IrAnalyze *ira, TypeTableEntry
         return result;
     }
+    // *T and [*]T can always cast to ?*c_void
+    if (wanted_type->id == TypeTableEntryIdPointer &&
+        wanted_type->data.pointer.ptr_len == PtrLenSingle &&
+        wanted_type->data.pointer.child_type == g->builtin_types.entry_c_void &&
+        actual_type->id == TypeTableEntryIdPointer &&
+        (!actual_type->data.pointer.is_const || wanted_type->data.pointer.is_const) &&
+        (!actual_type->data.pointer.is_volatile || wanted_type->data.pointer.is_volatile))
+    {
+        assert(actual_type->data.pointer.alignment >= wanted_type->data.pointer.alignment);
+        return result;
+    }
     // pointer const
     if (wanted_type->id == TypeTableEntryIdPointer && actual_type->id == TypeTableEntryIdPointer) {
         ConstCastOnly child = types_match_const_cast_only(ira, wanted_type->data.pointer.child_type,

test/cases/cast.zig+24

...	@@ -495,4 +495,28 @@ test "implicit cast from [N]T to ?[]T" {	...	@@ -495,4 +495,28 @@ test "implicit cast from [N]T to ?[]T" {
495	x.?[0] = 8;	495	x.?[0] = 8;
496	y[3] = 6;	496	y[3] = 6;
497	assert(std.mem.eql(u16, x.?[0..4], y[0..4]));	497	assert(std.mem.eql(u16, x.?[0..4], y[0..4]));
		498	}
		499
		500	test "implicit cast from T to ?c_void" {
		501	var a: u8 = 1;
		502	incrementVoidPtrValue(&a);
		503	std.debug.assert(a == 2);
		504	}
		505
		506	fn incrementVoidPtrValue(value: ?*c_void) void {
		507	@ptrCast(u8, value.?). += 1;
		508	}
		509
		510	test "implicit cast from []T to ?c_void" {
		511	var a = []u8{3, 2, 1};
		512	incrementVoidPtrArray(a[0..].ptr, 3);
		513	std.debug.assert(std.mem.eql(u8, a, []u8{4, 3, 2}));
		514	}
		515
		516	fn incrementVoidPtrArray(array: ?*c_void, len: usize) void {
		517	var n: usize = 0;
		518	while(n < len) : (n += 1) {
		519	std.debug.warn("{}", n);
		520	@ptrCast([*]u8, array.?)[n] += 1;
		521	}
498	}	522	}
	\ No newline at end of file

Allow implicit cast from *T and [*]T to ?*c_void

Allow implicit cast from T and []T to ?*c_void