Add borrowchk summoner

README.md

@@ -7,13 +7,15 @@
 Easy self-referential struct generation for Rust. 
 Dual licensed under MIT / Apache 2.0.
 
-Note: Version `0.11.0` and later place restrictions on derive macros, earlier
-versions allowed using them in ways which could lead to undefined behavior if
-not used properly.
-
-Note: Version `0.10.0` and later automatically box every field. This is done
-to prevent undefined behavior, but has the side effect of making the library
-easier to work with.
+Version notes:
+- Version `0.13.0` and later contain checks for additional situations which
+  cause undefined behavior if not caught.
+- Version `0.11.0` and later place restrictions on derive macros, earlier
+  versions allowed using them in ways which could lead to undefined behavior if
+  not used properly.
+- Version `0.10.0` and later automatically box every field. This is done
+  to prevent undefined behavior, but has the side effect of making the library
+  easier to work with.
 
 Tests are located in the examples/ folder because they need to be in a crate
 outside of `ouroboros` for the `self_referencing` macro to work properly.

examples/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ouroboros_examples"
-version = "0.12.0"
+version = "0.13.0"
 authors = ["Joshua Maros <[email protected]>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
@@ -19,7 +19,7 @@ default = []
 miri = []
 
 [dependencies]
-ouroboros = { version = "0.12.0", path = "../ouroboros" }
+ouroboros = { version = "0.13.0", path = "../ouroboros" }
 stable_deref_trait = "1.2"
 
 [dev-dependencies]

ouroboros/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ouroboros"
-version = "0.12.0"
+version = "0.13.0"
 authors = ["Joshua Maros <[email protected]>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
@@ -11,5 +11,5 @@ repository = "https://github.com/joshua-maros/ouroboros"
 
 [dependencies]
 aliasable = "0.1.3"
-ouroboros_macro = { version = "0.12.0", path = "../ouroboros_macro" }
+ouroboros_macro = { version = "0.13.0", path = "../ouroboros_macro" }
 stable_deref_trait = "1.2"

ouroboros_macro/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ouroboros_macro"
-version = "0.12.0"
+version = "0.13.0"
 authors = ["Joshua Maros <[email protected]>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"

ouroboros_macro/src/generate/constructor.rs

@@ -83,9 +83,6 @@ pub fn create_builder_and_constructor(
             // it work.
             let builder_name = field.builder_name();
             params.push(quote! { #builder_name : impl #bound_type });
-            // Ok so hear me out basically without this thing here my IDE thinks the rest of the
-            // code is a string and it all turns green.
-            {}
             doc_table += &format!(
                 "| `{}` | Use a function or closure: `(",
                 builder_name.to_string()

ouroboros_macro/src/generate/mod.rs

@@ -2,6 +2,7 @@ pub mod constructor;
 pub mod derives;
 pub mod into_heads;
 pub mod struc;
+pub mod summon_borrowchk;
 pub mod try_constructor;
 pub mod type_asserts;
 pub mod with_all;

ouroboros_macro/src/generate/summon_borrowchk.rs

@@ -0,0 +1,55 @@
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::Error;
+
+use crate::info_structures::{ArgType, StructInfo};
+
+pub fn generate_borrowchk_summoner(info: &StructInfo) -> Result<TokenStream, Error> {
+    let mut code: Vec<TokenStream> = Vec::new();
+    let mut params: Vec<TokenStream> = Vec::new();
+    let mut value_consumers: Vec<TokenStream> = Vec::new();
+    let mut template_consumers: Vec<TokenStream> = Vec::new();
+    for field in &info.fields {
+        let field_name = &field.name;
+
+        let arg_type = field.make_constructor_arg_type(&info, false)?;
+        if let ArgType::Plain(plain_type) = arg_type {
+            // No fancy builder function, we can just move the value directly into the struct.
+            params.push(quote! { #field_name: #plain_type });
+        } else if let ArgType::TraitBound(bound_type) = arg_type {
+            // Trait bounds are much trickier. We need a special syntax to accept them in the
+            // contructor, and generic parameters need to be added to the builder struct to make
+            // it work.
+            let builder_name = field.builder_name();
+            params.push(quote! { #builder_name : impl #bound_type });
+            let mut builder_args = Vec::new();
+            for (_, borrow) in field.borrows.iter().enumerate() {
+                let borrowed_name = &info.fields[borrow.index].name;
+                builder_args.push(quote! { &#borrowed_name });
+            }
+            code.push(quote! { let #field_name = #builder_name (#(#builder_args),*); });
+        }
+        if field.is_borrowed() {
+            let boxed = quote! { ::ouroboros::macro_help::aliasable_boxed(#field_name) };
+            code.push(quote! { let #field_name = #boxed; });
+        };
+        if !field.is_mutably_borrowed() {
+            value_consumers.push(quote! { #field_name: &#field_name });
+        }
+    }
+    for (_ty, ident) in info.generic_consumers() {
+        template_consumers.push(quote! { #ident: ::core::marker::PhantomData });
+    }
+    let generic_params = info.generic_params();
+    Ok(quote! {
+        fn check_if_okay_according_to_borrow_checker<#generic_params>(
+            #(#params,)*
+        ) {
+            #(#code;)*
+            BorrowedFields {
+                #(#value_consumers,)*
+                #(#template_consumers,)*
+            };
+        }
+    })
+}

ouroboros_macro/src/generate/with_all.rs

@@ -41,26 +41,14 @@ pub fn make_with_all_function(
         }
     }
 
-    let new_generic_params = if info.generic_params().is_empty() {
-        quote! { <'outer_borrow, 'this> }
-    } else {
-        for (ty, ident) in info.generic_consumers() {
-            fields.push(quote! { #ident: ::core::marker::PhantomData<#ty> });
-            mut_fields.push(quote! { #ident: ::core::marker::PhantomData<#ty> });
-            field_assignments.push(quote! { #ident: ::core::marker::PhantomData });
-            mut_field_assignments.push(quote! { #ident: ::core::marker::PhantomData });
-        }
-        let mut new_generic_params = info.generic_params().clone();
-        new_generic_params.insert(0, syn::parse_quote! { 'this });
-        new_generic_params.insert(0, syn::parse_quote! { 'outer_borrow });
-        quote! { <#new_generic_params> }
-    };
-    let new_generic_args = {
-        let mut args = info.generic_arguments();
-        args.insert(0, quote! { 'this });
-        args.insert(0, quote! { 'outer_borrow });
-        args
-    };
+    for (ty, ident) in info.generic_consumers() {
+        fields.push(quote! { #ident: ::core::marker::PhantomData<#ty> });
+        mut_fields.push(quote! { #ident: ::core::marker::PhantomData<#ty> });
+        field_assignments.push(quote! { #ident: ::core::marker::PhantomData });
+        mut_field_assignments.push(quote! { #ident: ::core::marker::PhantomData });
+    }
+    let new_generic_params = info.borrowed_generic_params();
+    let new_generic_args = info.borrowed_generic_arguments();
 
     let struct_documentation = format!(
         concat!(

ouroboros_macro/src/info_structures.rs

@@ -63,10 +63,30 @@ impl StructInfo {
         &self.generics.params
     }
 
+    /// Same as generic_params but with 'this and 'outer_borrow prepended.
+    pub fn borrowed_generic_params(&self) -> TokenStream {
+        if self.generic_params().is_empty() {
+            quote! { <'outer_borrow, 'this> }
+        } else {
+            let mut new_generic_params = self.generic_params().clone();
+            new_generic_params.insert(0, syn::parse_quote! { 'this });
+            new_generic_params.insert(0, syn::parse_quote! { 'outer_borrow });
+            quote! { <#new_generic_params> }
+        }
+    }
+
     pub fn generic_arguments(&self) -> Vec<TokenStream> {
         make_generic_arguments(&self.generics)
     }
 
+    /// Same as generic_arguments but with 'outer_borrow and 'this prepended.
+    pub fn borrowed_generic_arguments(&self) -> Vec<TokenStream> {
+        let mut args = self.generic_arguments();
+        args.insert(0, quote! { 'this });
+        args.insert(0, quote! { 'outer_borrow });
+        args
+    }
+
     pub fn generic_consumers(&self) -> impl Iterator<Item = (TokenStream, Ident)> {
         make_generic_consumers(&self.generics)
     }

ouroboros_macro/src/lib.rs

@@ -6,7 +6,17 @@ mod info_structures;
 mod parse;
 mod utils;
 
-use crate::{generate::{constructor::create_builder_and_constructor, derives::create_derives, into_heads::make_into_heads, struc::create_actual_struct_def, try_constructor::create_try_builder_and_constructor, type_asserts::make_type_asserts, with_all::make_with_all_function, with_each::make_with_functions}, info_structures::Options, parse::parse_struct};
+use crate::{
+    generate::{
+        constructor::create_builder_and_constructor, derives::create_derives,
+        into_heads::make_into_heads, struc::create_actual_struct_def,
+        summon_borrowchk::generate_borrowchk_summoner,
+        try_constructor::create_try_builder_and_constructor, type_asserts::make_type_asserts,
+        with_all::make_with_all_function, with_each::make_with_functions,
+    },
+    info_structures::Options,
+    parse::parse_struct,
+};
 use inflector::Inflector;
 use proc_macro::TokenStream;
 use proc_macro2::TokenStream as TokenStream2;
@@ -27,6 +37,8 @@ fn self_referencing_impl(
 
     let actual_struct_def = create_actual_struct_def(&info)?;
 
+    let borrowchk_summoner = generate_borrowchk_summoner(&info)?;
+
     let (builder_struct_name, builder_def, constructor_def) =
         create_builder_and_constructor(&info, options, false)?;
     let (async_builder_struct_name, async_builder_def, async_constructor_def) =
@@ -60,6 +72,7 @@ fn self_referencing_impl(
         mod #mod_name {
             use super::*;
             #actual_struct_def
+            #borrowchk_summoner
             #builder_def
             #async_builder_def
             #try_builder_def