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prevent implicitly increasing pointer alignment

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See #37
This commit is contained in:
Andrew Kelley 2017-08-29 15:19:15 -04:00
parent 8f682efbc5
commit be94299666
3 changed files with 65 additions and 10 deletions
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25
src/analyze.cpp
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@ -2615,25 +2615,30 @@ bool types_match_const_cast_only(TypeTableEntry *expected_type, TypeTableEntry *
(!actual_type->data.pointer.is_const || expected_type->data.pointer.is_const) &&
(!actual_type->data.pointer.is_volatile || expected_type->data.pointer.is_volatile) &&
actual_type->data.pointer.bit_offset == expected_type->data.pointer.bit_offset &&
actual_type->data.pointer.unaligned_bit_count == expected_type->data.pointer.unaligned_bit_count)
actual_type->data.pointer.unaligned_bit_count == expected_type->data.pointer.unaligned_bit_count &&
actual_type->data.pointer.alignment >= expected_type->data.pointer.alignment)
{
return types_match_const_cast_only(expected_type->data.pointer.child_type,
actual_type->data.pointer.child_type);
}
// unknown size array const
// slice const
if (expected_type->id == TypeTableEntryIdStruct &&
actual_type->id == TypeTableEntryIdStruct &&
expected_type->data.structure.is_slice &&
actual_type->data.structure.is_slice &&
(!actual_type->data.structure.fields[slice_ptr_index].type_entry->data.pointer.is_const ||
expected_type->data.structure.fields[slice_ptr_index].type_entry->data.pointer.is_const) &&
(!actual_type->data.structure.fields[slice_ptr_index].type_entry->data.pointer.is_volatile ||
expected_type->data.structure.fields[slice_ptr_index].type_entry->data.pointer.is_volatile))
actual_type->data.structure.is_slice)
{
return types_match_const_cast_only(
expected_type->data.structure.fields[slice_ptr_index].type_entry->data.pointer.child_type,
actual_type->data.structure.fields[slice_ptr_index].type_entry->data.pointer.child_type);
TypeTableEntry *actual_ptr_type = actual_type->data.structure.fields[slice_ptr_index].type_entry;
TypeTableEntry *expected_ptr_type = expected_type->data.structure.fields[slice_ptr_index].type_entry;
if ((!actual_ptr_type->data.pointer.is_const || expected_ptr_type->data.pointer.is_const) &&
(!actual_ptr_type->data.pointer.is_volatile || expected_ptr_type->data.pointer.is_volatile) &&
actual_ptr_type->data.pointer.bit_offset == expected_ptr_type->data.pointer.bit_offset &&
actual_ptr_type->data.pointer.unaligned_bit_count == expected_ptr_type->data.pointer.unaligned_bit_count &&
actual_ptr_type->data.pointer.alignment >= expected_ptr_type->data.pointer.alignment)
{
return types_match_const_cast_only(expected_ptr_type->data.pointer.child_type,
actual_ptr_type->data.pointer.child_type);
}
}
// maybe

15
test/cases/align.zig
View File

@ -38,3 +38,18 @@ test "bit field alignment" {
test "default alignment allows unspecified in type syntax" {
assert(&u32 == &align @alignOf(u32) u32);
}
test "implicitly decreasing pointer alignment" {
const a: u32 align 4 = 3;
const b: u32 align 8 = 4;
assert(addUnaligned(&a, &b) == 7);
}
fn addUnaligned(a: &align 1 const u32, b: &align 1 const u32) -> u32 { *a + *b }
test "implicitly decreasing slice alignment" {
const a: u32 align 4 = 3;
const b: u32 align 8 = 4;
assert(addUnalignedSlice((&a)[0..1], (&b)[0..1]) == 7);
}
fn addUnalignedSlice(a: []align 1 const u32, b: []align 1 const u32) -> u32 { a[0] + b[0] }

35
test/compile_errors.zig
View File

@ -1976,4 +1976,39 @@ pub fn addCases(cases: &tests.CompileErrorContext) {
\\}
,
".tmp_source.zig:1:1: error: declaration shadows type 'u16'");
cases.add("implicitly increasing pointer alignment",
\\const Foo = packed struct {
\\ a: u8,
\\ b: u32,
\\};
\\
\\export fn entry() {
\\ var foo = Foo { .a = 1, .b = 10 };
\\ bar(&foo.b);
\\}
\\
\\fn bar(x: &u32) {
\\ *x += 1;
\\}
,
".tmp_source.zig:8:13: error: expected type '&u32', found '&align 1 u32'");
cases.add("implicitly increasing slice alignment",
\\const Foo = packed struct {
\\ a: u8,
\\ b: u32,
\\};
\\
\\export fn entry() {
\\ var foo = Foo { .a = 1, .b = 10 };
\\ foo.b += 1;
\\ bar((&foo.b)[0..1]);
\\}
\\
\\fn bar(x: []u32) {
\\ x[0] += 1;
\\}
,
".tmp_source.zig:9:17: error: expected type '[]u32', found '[]align 1 u32'");
}