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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,30 @@ | ||
| use ouroboros::self_referencing; | ||
|
|
||
| pub struct PrintStrRef<'a>(&'a str); | ||
|
|
||
| impl Drop for PrintStrRef<'_> { | ||
| fn drop(&mut self) { | ||
| println!("Dropping {}", self.0); | ||
| } | ||
| } | ||
|
|
||
| #[self_referencing] | ||
| pub struct Tricky { | ||
| data1: String, | ||
| #[borrows(data1)] | ||
| #[covariant] | ||
| ref1: PrintStrRef<'this>, | ||
| data2: String, | ||
| } | ||
|
|
||
| fn main() { | ||
| let mut t = Tricky::new( | ||
| "A".to_owned(), | ||
| |a| PrintStrRef(a), | ||
| "B".to_owned(), | ||
| ); | ||
| t.with_mut(|fields| { | ||
| *fields.ref1 = PrintStrRef(fields.data2); | ||
| }); | ||
| drop(t); | ||
| } |
26 changes: 26 additions & 0 deletions
26
examples/src/fail_tests/swap_refs_for_use_after_free.stderr
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,26 @@ | ||
| error[E0597]: `t` does not live long enough | ||
| --> src/fail_tests/swap_refs_for_use_after_free.rs:26:5 | ||
| | | ||
| 26 | / t.with_mut(|fields| { | ||
| 27 | | *fields.ref1 = PrintStrRef(fields.data2); | ||
| 28 | | }); | ||
| | | ^ | ||
| | | | | ||
| | |______borrowed value does not live long enough | ||
| | argument requires that `t` is borrowed for `'static` | ||
| 29 | drop(t); | ||
| 30 | } | ||
| | - `t` dropped here while still borrowed | ||
|
|
||
| error[E0505]: cannot move out of `t` because it is borrowed | ||
| --> src/fail_tests/swap_refs_for_use_after_free.rs:29:10 | ||
| | | ||
| 26 | / t.with_mut(|fields| { | ||
| 27 | | *fields.ref1 = PrintStrRef(fields.data2); | ||
| 28 | | }); | ||
| | | - | ||
| | | | | ||
| | |______borrow of `t` occurs here | ||
| | argument requires that `t` is borrowed for `'static` | ||
| 29 | drop(t); | ||
| | ^ move out of `t` occurs here |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,128 @@ | ||
| use crate::{ | ||
| info_structures::{FieldType, Options, StructInfo}, | ||
| utils::{replace_this_with_lifetime, uses_this_lifetime}, | ||
| }; | ||
| use itertools::Itertools; | ||
| use proc_macro2::{Span, TokenStream}; | ||
| use quote::{format_ident, quote}; | ||
| use syn::{Error, Lifetime, WhereClause}; | ||
|
|
||
| pub fn make_with_all_mut_function( | ||
| info: &StructInfo, | ||
| options: Options, | ||
| ) -> Result<(TokenStream, TokenStream), Error> { | ||
| let visibility = if options.do_pub_extras { | ||
| info.vis.clone() | ||
| } else { | ||
| syn::parse_quote! { pub(super) } | ||
| }; | ||
| let mut mut_fields = Vec::new(); | ||
| let mut mut_field_assignments = Vec::new(); | ||
| let mut lifetime_idents = Vec::new(); | ||
| // I don't think the reverse is necessary but it does make the expanded code more uniform. | ||
| for field in info.fields.iter().rev() { | ||
| let field_name = &field.name; | ||
| let field_type = &field.typ; | ||
| let lifetime = format_ident!("this{}", lifetime_idents.len()); | ||
| if uses_this_lifetime(quote! { #field_type }) || field.field_type == FieldType::Borrowed { | ||
| lifetime_idents.push(lifetime.clone()); | ||
| } | ||
| let field_type = replace_this_with_lifetime(quote! { #field_type }, lifetime.clone()); | ||
| if field.field_type == FieldType::Tail { | ||
| mut_fields.push(quote! { #visibility #field_name: &'outer_borrow mut #field_type }); | ||
| mut_field_assignments.push(quote! { #field_name: &mut this.#field_name }); | ||
| } else if field.field_type == FieldType::Borrowed { | ||
| let ass = quote! { #field_name: unsafe { | ||
| ::ouroboros::macro_help::change_lifetime( | ||
| &*this.#field_name | ||
| ) | ||
| } }; | ||
| let lt = Lifetime::new(&format!("'{}", lifetime.to_string()), Span::call_site()); | ||
| mut_fields.push(quote! { #visibility #field_name: &#lt #field_type }); | ||
| mut_field_assignments.push(ass); | ||
| } else if field.field_type == FieldType::BorrowedMut { | ||
| // Add nothing because we cannot borrow something that has already been mutably | ||
| // borrowed. | ||
| } | ||
| } | ||
|
|
||
| for (ty, ident) in info.generic_consumers() { | ||
| mut_fields.push(quote! { #ident: ::core::marker::PhantomData<#ty> }); | ||
| mut_field_assignments.push(quote! { #ident: ::core::marker::PhantomData }); | ||
| } | ||
|
|
||
| let mut new_generic_params = info.generic_params().clone(); | ||
| for lt in &lifetime_idents { | ||
| let lt = Lifetime::new(&format!("'{}", lt.to_string()), Span::call_site()); | ||
| new_generic_params.insert(0, syn::parse_quote! { #lt }); | ||
| } | ||
| new_generic_params.insert(0, syn::parse_quote! { 'outer_borrow }); | ||
| let mut new_generic_args = info.generic_arguments(); | ||
| let mut lifetimes = Vec::new(); | ||
| for lt in &lifetime_idents { | ||
| let lt = Lifetime::new(&format!("'{}", lt.to_string()), Span::call_site()); | ||
| lifetimes.push(lt.clone()); | ||
| new_generic_args.insert(0, quote! { #lt }); | ||
| } | ||
| new_generic_args.insert(0, quote! { 'outer_borrow }); | ||
|
|
||
| let mut_struct_documentation = format!( | ||
| concat!( | ||
| "A struct for holding mutable references to all ", | ||
| "[tail fields](https://docs.rs/ouroboros/latest/ouroboros/attr.self_referencing.html#definitions) in an instance of ", | ||
| "[`{0}`]({0})." | ||
| ), | ||
| info.ident.to_string() | ||
| ); | ||
| let fake_lifetime = Lifetime::new(&format!("'{}", info.fake_lifetime()), Span::call_site()); | ||
| let mut generic_where = if let Some(clause) = &info.generics.where_clause { | ||
| clause.clone() | ||
| } else { | ||
| syn::parse_quote! { where } | ||
| }; | ||
| for lt in &lifetime_idents { | ||
| let lt = Lifetime::new(&format!("'{}", lt.to_string()), Span::call_site()); | ||
| let extra: WhereClause = syn::parse_quote! { where #fake_lifetime: #lt }; | ||
| generic_where | ||
| .predicates | ||
| .extend(extra.predicates.into_iter()); | ||
| } | ||
| for (outlives, lt) in lifetime_idents.iter().tuple_windows() { | ||
| let lt = Lifetime::new(&format!("'{}", lt.to_string()), Span::call_site()); | ||
| let outlives = Lifetime::new(&format!("'{}", outlives.to_string()), Span::call_site()); | ||
| let extra: WhereClause = syn::parse_quote! { where #lt: #outlives }; | ||
| generic_where | ||
| .predicates | ||
| .extend(extra.predicates.into_iter()); | ||
| } | ||
| let struct_defs = quote! { | ||
| #[doc=#mut_struct_documentation] | ||
| #visibility struct BorrowedMutFields <#new_generic_params> #generic_where { #(#mut_fields),* } | ||
| }; | ||
| let borrowed_mut_fields_type = quote! { BorrowedMutFields<#(#new_generic_args),*> }; | ||
| let mut_documentation = concat!( | ||
| "This method provides mutable references to all ", | ||
| "[tail fields](https://docs.rs/ouroboros/latest/ouroboros/attr.self_referencing.html#definitions).", | ||
| ); | ||
| let mut_documentation = if !options.do_no_doc { | ||
| quote! { | ||
| #[doc=#mut_documentation] | ||
| } | ||
| } else { | ||
| quote! { #[doc(hidden)] } | ||
| }; | ||
| let fn_defs = quote! { | ||
| #mut_documentation | ||
| #[inline(always)] | ||
| #visibility fn with_mut <'outer_borrow, ReturnType>( | ||
| &'outer_borrow mut self, | ||
| user: impl for<#(#lifetimes),*> ::core::ops::FnOnce(#borrowed_mut_fields_type) -> ReturnType | ||
| ) -> ReturnType { | ||
| let this = unsafe { self.actual_data.assume_init_mut() }; | ||
| user(BorrowedMutFields { | ||
| #(#mut_field_assignments),* | ||
| }) | ||
| } | ||
| }; | ||
| Ok((struct_defs, fn_defs)) | ||
| } |
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