From cb86c38cdbf29a400dd48ec8450ce71b81c8dd45 Mon Sep 17 00:00:00 2001 From: Daniel Henry-Mantilla Date: Fri, 26 Aug 2022 14:59:12 +0200 Subject: [PATCH 1/3] Fix `#[derive(Default)]` on a generic `#[default]` enum adding unnecessary `Default` bounds --- .../src/deriving/bounds.rs | 1 + .../src/deriving/clone.rs | 1 + .../src/deriving/cmp/eq.rs | 1 + .../src/deriving/cmp/ord.rs | 1 + .../src/deriving/cmp/partial_eq.rs | 1 + .../src/deriving/cmp/partial_ord.rs | 1 + .../src/deriving/debug.rs | 1 + .../src/deriving/decodable.rs | 1 + .../src/deriving/default.rs | 20 +++++++++++++++++++ .../src/deriving/encodable.rs | 1 + .../src/deriving/generic/mod.rs | 6 +++++- .../rustc_builtin_macros/src/deriving/hash.rs | 1 + 12 files changed, 35 insertions(+), 1 deletion(-) diff --git a/compiler/rustc_builtin_macros/src/deriving/bounds.rs b/compiler/rustc_builtin_macros/src/deriving/bounds.rs index 77e0b6c55a80e..7bd344467d032 100644 --- a/compiler/rustc_builtin_macros/src/deriving/bounds.rs +++ b/compiler/rustc_builtin_macros/src/deriving/bounds.rs @@ -16,6 +16,7 @@ pub fn expand_deriving_copy( let trait_def = TraitDef { span, path: path_std!(marker::Copy), + skip_path_as_bound: false, additional_bounds: Vec::new(), generics: Bounds::empty(), supports_unions: true, diff --git a/compiler/rustc_builtin_macros/src/deriving/clone.rs b/compiler/rustc_builtin_macros/src/deriving/clone.rs index c7f2d95e72f0c..fa8685f5f4e56 100644 --- a/compiler/rustc_builtin_macros/src/deriving/clone.rs +++ b/compiler/rustc_builtin_macros/src/deriving/clone.rs @@ -72,6 +72,7 @@ pub fn expand_deriving_clone( let trait_def = TraitDef { span, path: path_std!(clone::Clone), + skip_path_as_bound: false, additional_bounds: bounds, generics: Bounds::empty(), supports_unions: true, diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs index 5b556c5c9b9d1..eab67b0d354cf 100644 --- a/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs @@ -25,6 +25,7 @@ pub fn expand_deriving_eq( let trait_def = TraitDef { span, path: path_std!(cmp::Eq), + skip_path_as_bound: false, additional_bounds: Vec::new(), generics: Bounds::empty(), supports_unions: true, diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs index 7262586955811..7f117981a9a2f 100644 --- a/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs @@ -19,6 +19,7 @@ pub fn expand_deriving_ord( let trait_def = TraitDef { span, path: path_std!(cmp::Ord), + skip_path_as_bound: false, additional_bounds: Vec::new(), generics: Bounds::empty(), supports_unions: false, diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs index 42ee65b570a2a..236cbccaf9fee 100644 --- a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs @@ -83,6 +83,7 @@ pub fn expand_deriving_partial_eq( let trait_def = TraitDef { span, path: path_std!(cmp::PartialEq), + skip_path_as_bound: false, additional_bounds: Vec::new(), generics: Bounds::empty(), supports_unions: false, diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs index 516892aeda96f..4173403a1b84a 100644 --- a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs @@ -37,6 +37,7 @@ pub fn expand_deriving_partial_ord( let trait_def = TraitDef { span, path: path_std!(cmp::PartialOrd), + skip_path_as_bound: false, additional_bounds: vec![], generics: Bounds::empty(), supports_unions: false, diff --git a/compiler/rustc_builtin_macros/src/deriving/debug.rs b/compiler/rustc_builtin_macros/src/deriving/debug.rs index 4af7fd8165388..2cf614ed9476c 100644 --- a/compiler/rustc_builtin_macros/src/deriving/debug.rs +++ b/compiler/rustc_builtin_macros/src/deriving/debug.rs @@ -20,6 +20,7 @@ pub fn expand_deriving_debug( let trait_def = TraitDef { span, path: path_std!(fmt::Debug), + skip_path_as_bound: false, additional_bounds: Vec::new(), generics: Bounds::empty(), supports_unions: false, diff --git a/compiler/rustc_builtin_macros/src/deriving/decodable.rs b/compiler/rustc_builtin_macros/src/deriving/decodable.rs index 7174dbbe7ea8b..d669f616802fe 100644 --- a/compiler/rustc_builtin_macros/src/deriving/decodable.rs +++ b/compiler/rustc_builtin_macros/src/deriving/decodable.rs @@ -23,6 +23,7 @@ pub fn expand_deriving_rustc_decodable( let trait_def = TraitDef { span, path: Path::new_(vec![krate, sym::Decodable], vec![], PathKind::Global), + skip_path_as_bound: false, additional_bounds: Vec::new(), generics: Bounds::empty(), supports_unions: false, diff --git a/compiler/rustc_builtin_macros/src/deriving/default.rs b/compiler/rustc_builtin_macros/src/deriving/default.rs index a94c8a996e642..17df9fb279ad6 100644 --- a/compiler/rustc_builtin_macros/src/deriving/default.rs +++ b/compiler/rustc_builtin_macros/src/deriving/default.rs @@ -24,6 +24,7 @@ pub fn expand_deriving_default( let trait_def = TraitDef { span, path: Path::new(vec![kw::Default, sym::Default]), + skip_path_as_bound: has_a_default_variant(item), additional_bounds: Vec::new(), generics: Bounds::empty(), supports_unions: false, @@ -262,3 +263,22 @@ impl<'a, 'b> rustc_ast::visit::Visitor<'a> for DetectNonVariantDefaultAttr<'a, ' } } } + +fn has_a_default_variant(item: &Annotatable) -> bool { + struct HasDefaultAttrOnVariant { + found: bool, + } + + impl<'ast> rustc_ast::visit::Visitor<'ast> for HasDefaultAttrOnVariant { + fn visit_variant(&mut self, v: &'ast rustc_ast::Variant) { + if v.attrs.iter().any(|attr| attr.has_name(kw::Default)) { + self.found = true; + } + // no need to subrecurse. + } + } + + let mut visitor = HasDefaultAttrOnVariant { found: false }; + item.visit_with(&mut visitor); + visitor.found +} diff --git a/compiler/rustc_builtin_macros/src/deriving/encodable.rs b/compiler/rustc_builtin_macros/src/deriving/encodable.rs index b220e54238f46..f83f58b97d38f 100644 --- a/compiler/rustc_builtin_macros/src/deriving/encodable.rs +++ b/compiler/rustc_builtin_macros/src/deriving/encodable.rs @@ -107,6 +107,7 @@ pub fn expand_deriving_rustc_encodable( let trait_def = TraitDef { span, path: Path::new_(vec![krate, sym::Encodable], vec![], PathKind::Global), + skip_path_as_bound: false, additional_bounds: Vec::new(), generics: Bounds::empty(), supports_unions: false, diff --git a/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs b/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs index adffebd3fd285..cd53050c61e68 100644 --- a/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs +++ b/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs @@ -172,6 +172,7 @@ use rustc_span::symbol::{kw, sym, Ident, Symbol}; use rustc_span::Span; use std::cell::RefCell; use std::iter; +use std::ops::Not; use std::vec; use thin_vec::thin_vec; use ty::{Bounds, Path, Ref, Self_, Ty}; @@ -185,6 +186,9 @@ pub struct TraitDef<'a> { /// Path of the trait, including any type parameters pub path: Path, + /// Whether to skip adding the current trait as a bound to the type parameters of the type. + pub skip_path_as_bound: bool, + /// Additional bounds required of any type parameters of the type, /// other than the current trait pub additional_bounds: Vec, @@ -594,7 +598,7 @@ impl<'a> TraitDef<'a> { cx.trait_bound(p.to_path(cx, self.span, type_ident, generics)) }).chain( // require the current trait - iter::once(cx.trait_bound(trait_path.clone())) + self.skip_path_as_bound.not().then(|| cx.trait_bound(trait_path.clone())) ).chain( // also add in any bounds from the declaration param.bounds.iter().cloned() diff --git a/compiler/rustc_builtin_macros/src/deriving/hash.rs b/compiler/rustc_builtin_macros/src/deriving/hash.rs index f1f02e7ce7787..6e9d5f08b9443 100644 --- a/compiler/rustc_builtin_macros/src/deriving/hash.rs +++ b/compiler/rustc_builtin_macros/src/deriving/hash.rs @@ -22,6 +22,7 @@ pub fn expand_deriving_hash( let hash_trait_def = TraitDef { span, path, + skip_path_as_bound: false, additional_bounds: Vec::new(), generics: Bounds::empty(), supports_unions: false, From 975e72fc0f122e2c2b57d8d61a9c6553d29fb366 Mon Sep 17 00:00:00 2001 From: Daniel Henry-Mantilla Date: Fri, 26 Aug 2022 15:00:38 +0200 Subject: [PATCH 2/3] Add corresponding regression test --- src/test/ui/deriving/deriving-default-enum.rs | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/src/test/ui/deriving/deriving-default-enum.rs b/src/test/ui/deriving/deriving-default-enum.rs index d1a81c72c2fdc..1c7a501edc705 100644 --- a/src/test/ui/deriving/deriving-default-enum.rs +++ b/src/test/ui/deriving/deriving-default-enum.rs @@ -12,6 +12,16 @@ enum Foo { Beta(NotDefault), } +// #[default] on a generic enum does not add `Default` bounds to the type params. +#[derive(Default)] +enum MyOption { + #[default] + None, + #[allow(dead_code)] + Some(T), +} + fn main() { assert_eq!(Foo::default(), Foo::Alpha); + assert!(matches!(MyOption::::default(), MyOption::None)); } From 3d4980bc8d8a58df217a6b659b9353a11ce4cd29 Mon Sep 17 00:00:00 2001 From: Daniel Henry-Mantilla Date: Thu, 15 Sep 2022 18:56:12 +0200 Subject: [PATCH 3/3] Future-proof against loose bounds if default variant is non-exhaustive. Co-Authored-By: Mark Rousskov --- src/test/ui/macros/macros-nonfatal-errors.rs | 21 +++++++++++++++++++ .../ui/macros/macros-nonfatal-errors.stderr | 12 ++++++++++- 2 files changed, 32 insertions(+), 1 deletion(-) diff --git a/src/test/ui/macros/macros-nonfatal-errors.rs b/src/test/ui/macros/macros-nonfatal-errors.rs index e7a01f105de0b..140cc5b0fd808 100644 --- a/src/test/ui/macros/macros-nonfatal-errors.rs +++ b/src/test/ui/macros/macros-nonfatal-errors.rs @@ -116,3 +116,24 @@ fn main() { trace_macros!(invalid); //~ ERROR } + +/// Check that `#[derive(Default)]` does use a `T : Default` bound when the +/// `#[default]` variant is `#[non_exhaustive]` (should this end up allowed). +const _: () = { + #[derive(Default)] + enum NonExhaustiveDefaultGeneric { + #[default] + #[non_exhaustive] + Foo, //~ ERROR default variant must be exhaustive + Bar(T), + } + + fn assert_impls_default() {} + + enum NotDefault {} + + // Note: the `derive(Default)` currently bails early enough for trait-checking + // not to happen. Should it bail late enough, or even pass, make sure to + // assert that the following line fails. + let _ = assert_impls_default::>; +}; diff --git a/src/test/ui/macros/macros-nonfatal-errors.stderr b/src/test/ui/macros/macros-nonfatal-errors.stderr index b3c6d07f96763..d42f6c179b7ef 100644 --- a/src/test/ui/macros/macros-nonfatal-errors.stderr +++ b/src/test/ui/macros/macros-nonfatal-errors.stderr @@ -215,11 +215,21 @@ error: trace_macros! accepts only `true` or `false` LL | trace_macros!(invalid); | ^^^^^^^^^^^^^^^^^^^^^^ +error: default variant must be exhaustive + --> $DIR/macros-nonfatal-errors.rs:127:9 + | +LL | #[non_exhaustive] + | ----------------- declared `#[non_exhaustive]` here +LL | Foo, + | ^^^ + | + = help: consider a manual implementation of `Default` + error: cannot find macro `llvm_asm` in this scope --> $DIR/macros-nonfatal-errors.rs:99:5 | LL | llvm_asm!(invalid); | ^^^^^^^^ -error: aborting due to 27 previous errors +error: aborting due to 28 previous errors