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translate-c: Flexible array members must be the last field in a struct

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Previously any zero-length or incomplete array within a struct was treated
as a flexible array member.
This commit is contained in:
Evan Haas 2023-08-15 21:37:57 -07:00
parent 340a45683c
commit bdf5739c0a
1 changed files with 19 additions and 7 deletions
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26
src/translate_c.zig
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@ -1049,21 +1049,33 @@ fn buildFlexibleArrayFn(
return Node.initPayload(&payload.base);
}
/// Return true if `field_decl` is the flexible array field for its parent record
fn isFlexibleArrayFieldDecl(c: *Context, field_decl: *const clang.FieldDecl) bool {
return qualTypeCanon(field_decl.getType()).isIncompleteOrZeroLengthArrayType(c.clang_context);
const record_decl = field_decl.getParent() orelse return false;
const record_flexible_field = flexibleArrayField(c, record_decl) orelse return false;
return field_decl == record_flexible_field;
}
/// Find the flexible array field for a record if any. A flexible array field is an
/// incomplete or zero-length array that occurs as the last field of a record.
/// clang's RecordDecl::hasFlexibleArrayMember is not suitable for determining
/// this because it returns false for a record that ends with a zero-length
/// array, but we consider those to be flexible arrays
fn hasFlexibleArrayField(c: *Context, record_def: *const clang.RecordDecl) bool {
fn flexibleArrayField(c: *Context, record_def: *const clang.RecordDecl) ?*const clang.FieldDecl {
var it = record_def.field_begin();
const end_it = record_def.field_end();
var flexible_field: ?*const clang.FieldDecl = null;
while (it.neq(end_it)) : (it = it.next()) {
const field_decl = it.deref();
if (isFlexibleArrayFieldDecl(c, field_decl)) return true;
const ty = qualTypeCanon(field_decl.getType());
const incomplete_or_zero_size = ty.isIncompleteOrZeroLengthArrayType(c.clang_context);
if (incomplete_or_zero_size) {
flexible_field = field_decl;
} else {
flexible_field = null;
}
}
return false;
return flexible_field;
}
fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordDecl) Error!void {
@ -1117,7 +1129,7 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
var functions = std.ArrayList(Node).init(c.gpa);
defer functions.deinit();
const has_flexible_array = hasFlexibleArrayField(c, record_def);
const flexible_field = flexibleArrayField(c, record_def);
var unnamed_field_count: u32 = 0;
var it = record_def.field_begin();
const end_it = record_def.field_end();
@ -1143,7 +1155,7 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
unnamed_field_count += 1;
is_anon = true;
}
if (isFlexibleArrayFieldDecl(c, field_decl)) {
if (flexible_field == field_decl) {
const flexible_array_fn = buildFlexibleArrayFn(c, scope, layout, field_name, field_decl) catch |err| switch (err) {
error.UnsupportedType => {
try c.opaque_demotes.put(c.gpa, @intFromPtr(record_decl.getCanonicalDecl()), {});
@ -1164,7 +1176,7 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
else => |e| return e,
};
const alignment = if (has_flexible_array and field_decl.getFieldIndex() == 0)
const alignment = if (flexible_field != null and field_decl.getFieldIndex() == 0)
@as(c_uint, @intCast(record_alignment))
else
ClangAlignment.forField(c, field_decl, record_def).zigAlignment();