From ea188e9d21cd88222be1972f18cc50da97173607 Mon Sep 17 00:00:00 2001 From: Yuki Okushi Date: Mon, 14 Jun 2021 07:04:56 +0900 Subject: [PATCH] Permit zero non-zero-field on transparent types --- compiler/rustc_typeck/src/check/check.rs | 2 +- compiler/rustc_typeck/src/check/mod.rs | 6 +- src/test/ui/repr/repr-transparent.rs | 32 +++++---- src/test/ui/repr/repr-transparent.stderr | 82 +++++++----------------- 4 files changed, 46 insertions(+), 76 deletions(-) diff --git a/compiler/rustc_typeck/src/check/check.rs b/compiler/rustc_typeck/src/check/check.rs index 70d85796d00..77644ea1c3c 100644 --- a/compiler/rustc_typeck/src/check/check.rs +++ b/compiler/rustc_typeck/src/check/check.rs @@ -1382,7 +1382,7 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, adt: &'tcx ty let non_zst_fields = field_infos.clone().filter_map(|(span, zst, _align1)| if !zst { Some(span) } else { None }); let non_zst_count = non_zst_fields.clone().count(); - if non_zst_count != 1 { + if non_zst_count >= 2 { bad_non_zero_sized_fields(tcx, adt, non_zst_count, non_zst_fields, sp); } for (span, zst, align1) in field_infos { diff --git a/compiler/rustc_typeck/src/check/mod.rs b/compiler/rustc_typeck/src/check/mod.rs index ad7853b7cd0..72d94c3a9c9 100644 --- a/compiler/rustc_typeck/src/check/mod.rs +++ b/compiler/rustc_typeck/src/check/mod.rs @@ -1029,7 +1029,7 @@ fn suggestion_signature(assoc: &ty::AssocItem, tcx: TyCtxt<'_>) -> String { } } -/// Emit an error when encountering more or less than one variant in a transparent enum. +/// Emit an error when encountering two or more variants in a transparent enum. fn bad_variant_count<'tcx>(tcx: TyCtxt<'tcx>, adt: &'tcx ty::AdtDef, sp: Span, did: DefId) { let variant_spans: Vec<_> = adt .variants @@ -1048,7 +1048,7 @@ fn bad_variant_count<'tcx>(tcx: TyCtxt<'tcx>, adt: &'tcx ty::AdtDef, sp: Span, d err.emit(); } -/// Emit an error when encountering more or less than one non-zero-sized field in a transparent +/// Emit an error when encountering two or more non-zero-sized fields in a transparent /// enum. fn bad_non_zero_sized_fields<'tcx>( tcx: TyCtxt<'tcx>, @@ -1057,7 +1057,7 @@ fn bad_non_zero_sized_fields<'tcx>( field_spans: impl Iterator, sp: Span, ) { - let msg = format!("needs exactly one non-zero-sized field, but has {}", field_count); + let msg = format!("needs at most one non-zero-sized field, but has {}", field_count); let mut err = struct_span_err!( tcx.sess, sp, diff --git a/src/test/ui/repr/repr-transparent.rs b/src/test/ui/repr/repr-transparent.rs index 8fbdb4cc80b..8c9d1639c0a 100644 --- a/src/test/ui/repr/repr-transparent.rs +++ b/src/test/ui/repr/repr-transparent.rs @@ -8,27 +8,29 @@ use std::marker::PhantomData; #[repr(transparent)] -struct NoFields; //~ ERROR needs exactly one non-zero-sized field +struct NoFields; #[repr(transparent)] -struct ContainsOnlyZst(()); //~ ERROR needs exactly one non-zero-sized field +struct ContainsOnlyZst(()); #[repr(transparent)] -struct ContainsOnlyZstArray([bool; 0]); //~ ERROR needs exactly one non-zero-sized field +struct ContainsOnlyZstArray([bool; 0]); #[repr(transparent)] struct ContainsMultipleZst(PhantomData<*const i32>, NoFields); -//~^ ERROR needs exactly one non-zero-sized field #[repr(transparent)] -struct MultipleNonZst(u8, u8); //~ ERROR needs exactly one non-zero-sized field +struct ContainsZstAndNonZst((), [i32; 2]); + +#[repr(transparent)] +struct MultipleNonZst(u8, u8); //~ ERROR needs at most one non-zero-sized field trait Mirror { type It: ?Sized; } impl Mirror for T { type It = Self; } #[repr(transparent)] pub struct StructWithProjection(f32, ::It); -//~^ ERROR needs exactly one non-zero-sized field +//~^ ERROR needs at most one non-zero-sized field #[repr(transparent)] struct NontrivialAlignZst(u32, [u16; 0]); //~ ERROR alignment larger than 1 @@ -40,22 +42,26 @@ struct ZstAlign32(PhantomData); struct GenericAlign(ZstAlign32, u32); //~ ERROR alignment larger than 1 #[repr(transparent)] //~ ERROR unsupported representation for zero-variant enum -enum Void {} -//~^ ERROR transparent enum needs exactly one variant, but has 0 +enum Void {} //~ ERROR transparent enum needs exactly one variant, but has 0 #[repr(transparent)] -enum FieldlessEnum { //~ ERROR transparent enum needs exactly one non-zero-sized field, but has 0 +enum FieldlessEnum { Foo, } +#[repr(transparent)] +enum UnitFieldEnum { + Foo(()), +} + #[repr(transparent)] enum TooManyFieldsEnum { Foo(u32, String), } -//~^^^ ERROR transparent enum needs exactly one non-zero-sized field, but has 2 +//~^^^ ERROR transparent enum needs at most one non-zero-sized field, but has 2 #[repr(transparent)] -enum TooManyVariants { //~ ERROR transparent enum needs exactly one variant, but has 2 +enum MultipleVariants { //~ ERROR transparent enum needs exactly one variant, but has 2 Foo(String), Bar, } @@ -71,12 +77,12 @@ enum GenericAlignEnum { } #[repr(transparent)] -union UnitUnion { //~ ERROR transparent union needs exactly one non-zero-sized field, but has 0 +union UnitUnion { u: (), } #[repr(transparent)] -union TooManyFields { //~ ERROR transparent union needs exactly one non-zero-sized field, but has 2 +union TooManyFields { //~ ERROR transparent union needs at most one non-zero-sized field, but has 2 u: u32, s: i32 } diff --git a/src/test/ui/repr/repr-transparent.stderr b/src/test/ui/repr/repr-transparent.stderr index cbc74fbb6a2..001a181881f 100644 --- a/src/test/ui/repr/repr-transparent.stderr +++ b/src/test/ui/repr/repr-transparent.stderr @@ -1,61 +1,37 @@ -error[E0690]: transparent struct needs exactly one non-zero-sized field, but has 0 - --> $DIR/repr-transparent.rs:11:1 - | -LL | struct NoFields; - | ^^^^^^^^^^^^^^^^ needs exactly one non-zero-sized field, but has 0 - -error[E0690]: transparent struct needs exactly one non-zero-sized field, but has 0 - --> $DIR/repr-transparent.rs:14:1 - | -LL | struct ContainsOnlyZst(()); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ needs exactly one non-zero-sized field, but has 0 - -error[E0690]: transparent struct needs exactly one non-zero-sized field, but has 0 - --> $DIR/repr-transparent.rs:17:1 - | -LL | struct ContainsOnlyZstArray([bool; 0]); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ needs exactly one non-zero-sized field, but has 0 - -error[E0690]: transparent struct needs exactly one non-zero-sized field, but has 0 - --> $DIR/repr-transparent.rs:20:1 - | -LL | struct ContainsMultipleZst(PhantomData<*const i32>, NoFields); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ needs exactly one non-zero-sized field, but has 0 - -error[E0690]: transparent struct needs exactly one non-zero-sized field, but has 2 - --> $DIR/repr-transparent.rs:24:1 +error[E0690]: transparent struct needs at most one non-zero-sized field, but has 2 + --> $DIR/repr-transparent.rs:26:1 | LL | struct MultipleNonZst(u8, u8); | ^^^^^^^^^^^^^^^^^^^^^^--^^--^^ | | | | | | | this field is non-zero-sized | | this field is non-zero-sized - | needs exactly one non-zero-sized field, but has 2 + | needs at most one non-zero-sized field, but has 2 -error[E0690]: transparent struct needs exactly one non-zero-sized field, but has 2 - --> $DIR/repr-transparent.rs:30:1 +error[E0690]: transparent struct needs at most one non-zero-sized field, but has 2 + --> $DIR/repr-transparent.rs:32:1 | LL | pub struct StructWithProjection(f32, ::It); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---^^-------------------^^ | | | | | | | this field is non-zero-sized | | this field is non-zero-sized - | needs exactly one non-zero-sized field, but has 2 + | needs at most one non-zero-sized field, but has 2 error[E0691]: zero-sized field in transparent struct has alignment larger than 1 - --> $DIR/repr-transparent.rs:34:32 + --> $DIR/repr-transparent.rs:36:32 | LL | struct NontrivialAlignZst(u32, [u16; 0]); | ^^^^^^^^ has alignment larger than 1 error[E0691]: zero-sized field in transparent struct has alignment larger than 1 - --> $DIR/repr-transparent.rs:40:24 + --> $DIR/repr-transparent.rs:42:24 | LL | struct GenericAlign(ZstAlign32, u32); | ^^^^^^^^^^^^^ has alignment larger than 1 error[E0084]: unsupported representation for zero-variant enum - --> $DIR/repr-transparent.rs:42:1 + --> $DIR/repr-transparent.rs:44:1 | LL | #[repr(transparent)] | ^^^^^^^^^^^^^^^^^^^^ @@ -63,66 +39,54 @@ LL | enum Void {} | ------------ zero-variant enum error[E0731]: transparent enum needs exactly one variant, but has 0 - --> $DIR/repr-transparent.rs:43:1 + --> $DIR/repr-transparent.rs:45:1 | LL | enum Void {} | ^^^^^^^^^ needs exactly one variant, but has 0 -error[E0690]: the variant of a transparent enum needs exactly one non-zero-sized field, but has 0 - --> $DIR/repr-transparent.rs:47:1 - | -LL | enum FieldlessEnum { - | ^^^^^^^^^^^^^^^^^^ needs exactly one non-zero-sized field, but has 0 - -error[E0690]: the variant of a transparent enum needs exactly one non-zero-sized field, but has 2 - --> $DIR/repr-transparent.rs:52:1 +error[E0690]: the variant of a transparent enum needs at most one non-zero-sized field, but has 2 + --> $DIR/repr-transparent.rs:58:1 | LL | enum TooManyFieldsEnum { - | ^^^^^^^^^^^^^^^^^^^^^^ needs exactly one non-zero-sized field, but has 2 + | ^^^^^^^^^^^^^^^^^^^^^^ needs at most one non-zero-sized field, but has 2 LL | Foo(u32, String), | --- ------ this field is non-zero-sized | | | this field is non-zero-sized error[E0731]: transparent enum needs exactly one variant, but has 2 - --> $DIR/repr-transparent.rs:58:1 + --> $DIR/repr-transparent.rs:64:1 | -LL | enum TooManyVariants { - | ^^^^^^^^^^^^^^^^^^^^ needs exactly one variant, but has 2 +LL | enum MultipleVariants { + | ^^^^^^^^^^^^^^^^^^^^^ needs exactly one variant, but has 2 LL | Foo(String), | ----------- LL | Bar, - | --- too many variants in `TooManyVariants` + | --- too many variants in `MultipleVariants` error[E0691]: zero-sized field in transparent enum has alignment larger than 1 - --> $DIR/repr-transparent.rs:65:14 + --> $DIR/repr-transparent.rs:71:14 | LL | Foo(u32, [u16; 0]), | ^^^^^^^^ has alignment larger than 1 error[E0691]: zero-sized field in transparent enum has alignment larger than 1 - --> $DIR/repr-transparent.rs:70:11 + --> $DIR/repr-transparent.rs:76:11 | LL | Foo { bar: ZstAlign32, baz: u32 } | ^^^^^^^^^^^^^^^^^^ has alignment larger than 1 -error[E0690]: transparent union needs exactly one non-zero-sized field, but has 0 - --> $DIR/repr-transparent.rs:74:1 - | -LL | union UnitUnion { - | ^^^^^^^^^^^^^^^ needs exactly one non-zero-sized field, but has 0 - -error[E0690]: transparent union needs exactly one non-zero-sized field, but has 2 - --> $DIR/repr-transparent.rs:79:1 +error[E0690]: transparent union needs at most one non-zero-sized field, but has 2 + --> $DIR/repr-transparent.rs:85:1 | LL | union TooManyFields { - | ^^^^^^^^^^^^^^^^^^^ needs exactly one non-zero-sized field, but has 2 + | ^^^^^^^^^^^^^^^^^^^ needs at most one non-zero-sized field, but has 2 LL | u: u32, | ------ this field is non-zero-sized LL | s: i32 | ------ this field is non-zero-sized -error: aborting due to 17 previous errors +error: aborting due to 11 previous errors Some errors have detailed explanations: E0084, E0690, E0691, E0731. For more information about an error, try `rustc --explain E0084`.