diff options
Diffstat (limited to 'src/libsyntax')
| -rw-r--r-- | src/libsyntax/ext/deriving/generic/mod.rs | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/libsyntax/ext/deriving/generic/mod.rs b/src/libsyntax/ext/deriving/generic/mod.rs index c3478266db2..de77baa0ef2 100644 --- a/src/libsyntax/ext/deriving/generic/mod.rs +++ b/src/libsyntax/ext/deriving/generic/mod.rs @@ -1181,6 +1181,17 @@ impl<'a> MethodDef<'a> { rules: ast::UnsafeBlock(ast::CompilerGenerated), span: sp })); + // FIXME: This unconditionally casts to `isize`. However: + // + // 1. On 32-bit platforms, that will truncate 64-bit enums + // that are making use of the upper 32 bits, and + // + // 2. On all platforms, it will misinterpret the sign bit + // of a 64-bit enum. + // + // What it should do is lookup whether the enum has an + // repr-attribute and cast to that if necessary. But + // attributes are not yet available to this function. let target_ty = cx.ty_ident(sp, cx.ident_of("isize")); let variant_disr = cx.expr_cast(sp, variant_value, target_ty); let let_stmt = cx.stmt_let(sp, false, ident, variant_disr); |