Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 347 insertions, 0 deletions

diff --git a/third_party/rust/derive_arbitrary/src/lib.rs b/third_party/rust/derive_arbitrary/src/lib.rs
new file mode 100644
index 0000000000..b7292ab7bb
--- /dev/null
+++ b/third_party/rust/derive_arbitrary/src/lib.rs
@@ -0,0 +1,347 @@
+extern crate proc_macro;
+
+use proc_macro2::{Span, TokenStream};
+use quote::quote;
+use syn::*;
+
+mod field_attributes;
+use field_attributes::{determine_field_constructor, FieldConstructor};
+
+static ARBITRARY_LIFETIME_NAME: &str = "'arbitrary";
+
+#[proc_macro_derive(Arbitrary, attributes(arbitrary))]
+pub fn derive_arbitrary(tokens: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    let input = syn::parse_macro_input!(tokens as syn::DeriveInput);
+    expand_derive_arbitrary(input)
+        .unwrap_or_else(syn::Error::into_compile_error)
+        .into()
+}
+
+fn expand_derive_arbitrary(input: syn::DeriveInput) -> Result<TokenStream> {
+    let (lifetime_without_bounds, lifetime_with_bounds) =
+        build_arbitrary_lifetime(input.generics.clone());
+
+    let recursive_count = syn::Ident::new(
+        &format!("RECURSIVE_COUNT_{}", input.ident),
+        Span::call_site(),
+    );
+
+    let arbitrary_method =
+        gen_arbitrary_method(&input, lifetime_without_bounds.clone(), &recursive_count)?;
+    let size_hint_method = gen_size_hint_method(&input)?;
+    let name = input.ident;
+    // Add a bound `T: Arbitrary` to every type parameter T.
+    let generics = add_trait_bounds(input.generics, lifetime_without_bounds.clone());
+
+    // Build ImplGeneric with a lifetime (https://github.com/dtolnay/syn/issues/90)
+    let mut generics_with_lifetime = generics.clone();
+    generics_with_lifetime
+        .params
+        .push(GenericParam::Lifetime(lifetime_with_bounds));
+    let (impl_generics, _, _) = generics_with_lifetime.split_for_impl();
+
+    // Build TypeGenerics and WhereClause without a lifetime
+    let (_, ty_generics, where_clause) = generics.split_for_impl();
+
+    Ok(quote! {
+        const _: () = {
+            std::thread_local! {
+                #[allow(non_upper_case_globals)]
+                static #recursive_count: std::cell::Cell<u32> = std::cell::Cell::new(0);
+            }
+
+            impl #impl_generics arbitrary::Arbitrary<#lifetime_without_bounds> for #name #ty_generics #where_clause {
+                #arbitrary_method
+                #size_hint_method
+            }
+        };
+    })
+}
+
+// Returns: (lifetime without bounds, lifetime with bounds)
+// Example: ("'arbitrary", "'arbitrary: 'a + 'b")
+fn build_arbitrary_lifetime(generics: Generics) -> (LifetimeDef, LifetimeDef) {
+    let lifetime_without_bounds =
+        LifetimeDef::new(Lifetime::new(ARBITRARY_LIFETIME_NAME, Span::call_site()));
+    let mut lifetime_with_bounds = lifetime_without_bounds.clone();
+
+    for param in generics.params.iter() {
+        if let GenericParam::Lifetime(lifetime_def) = param {
+            lifetime_with_bounds
+                .bounds
+                .push(lifetime_def.lifetime.clone());
+        }
+    }
+
+    (lifetime_without_bounds, lifetime_with_bounds)
+}
+
+// Add a bound `T: Arbitrary` to every type parameter T.
+fn add_trait_bounds(mut generics: Generics, lifetime: LifetimeDef) -> Generics {
+    for param in generics.params.iter_mut() {
+        if let GenericParam::Type(type_param) = param {
+            type_param
+                .bounds
+                .push(parse_quote!(arbitrary::Arbitrary<#lifetime>));
+        }
+    }
+    generics
+}
+
+fn with_recursive_count_guard(
+    recursive_count: &syn::Ident,
+    expr: impl quote::ToTokens,
+) -> impl quote::ToTokens {
+    quote! {
+        let guard_against_recursion = u.is_empty();
+        if guard_against_recursion {
+            #recursive_count.with(|count| {
+                if count.get() > 0 {
+                    return Err(arbitrary::Error::NotEnoughData);
+                }
+                count.set(count.get() + 1);
+                Ok(())
+            })?;
+        }
+
+        let result = (|| { #expr })();
+
+        if guard_against_recursion {
+            #recursive_count.with(|count| {
+                count.set(count.get() - 1);
+            });
+        }
+
+        result
+    }
+}
+
+fn gen_arbitrary_method(
+    input: &DeriveInput,
+    lifetime: LifetimeDef,
+    recursive_count: &syn::Ident,
+) -> Result<TokenStream> {
+    fn arbitrary_structlike(
+        fields: &Fields,
+        ident: &syn::Ident,
+        lifetime: LifetimeDef,
+        recursive_count: &syn::Ident,
+    ) -> Result<TokenStream> {
+        let arbitrary = construct(fields, |_idx, field| gen_constructor_for_field(field))?;
+        let body = with_recursive_count_guard(recursive_count, quote! { Ok(#ident #arbitrary) });
+
+        let arbitrary_take_rest = construct_take_rest(fields)?;
+        let take_rest_body =
+            with_recursive_count_guard(recursive_count, quote! { Ok(#ident #arbitrary_take_rest) });
+
+        Ok(quote! {
+            fn arbitrary(u: &mut arbitrary::Unstructured<#lifetime>) -> arbitrary::Result<Self> {
+                #body
+            }
+
+            fn arbitrary_take_rest(mut u: arbitrary::Unstructured<#lifetime>) -> arbitrary::Result<Self> {
+                #take_rest_body
+            }
+        })
+    }
+
+    let ident = &input.ident;
+    let output = match &input.data {
+        Data::Struct(data) => arbitrary_structlike(&data.fields, ident, lifetime, recursive_count)?,
+        Data::Union(data) => arbitrary_structlike(
+            &Fields::Named(data.fields.clone()),
+            ident,
+            lifetime,
+            recursive_count,
+        )?,
+        Data::Enum(data) => {
+            let variants: Vec<TokenStream> = data
+                .variants
+                .iter()
+                .enumerate()
+                .map(|(i, variant)| {
+                    let idx = i as u64;
+                    let variant_name = &variant.ident;
+                    construct(&variant.fields, |_, field| gen_constructor_for_field(field))
+                        .map(|ctor| quote! { #idx => #ident::#variant_name #ctor })
+                })
+                .collect::<Result<_>>()?;
+
+            let variants_take_rest: Vec<TokenStream> = data
+                .variants
+                .iter()
+                .enumerate()
+                .map(|(i, variant)| {
+                    let idx = i as u64;
+                    let variant_name = &variant.ident;
+                    construct_take_rest(&variant.fields)
+                        .map(|ctor| quote! { #idx => #ident::#variant_name #ctor })
+                })
+                .collect::<Result<_>>()?;
+
+            let count = data.variants.len() as u64;
+
+            let arbitrary = with_recursive_count_guard(
+                recursive_count,
+                quote! {
+                    // Use a multiply + shift to generate a ranged random number
+                    // with slight bias. For details, see:
+                    // https://lemire.me/blog/2016/06/30/fast-random-shuffling
+                    Ok(match (u64::from(<u32 as arbitrary::Arbitrary>::arbitrary(u)?) * #count) >> 32 {
+                        #(#variants,)*
+                        _ => unreachable!()
+                    })
+                },
+            );
+
+            let arbitrary_take_rest = with_recursive_count_guard(
+                recursive_count,
+                quote! {
+                    // Use a multiply + shift to generate a ranged random number
+                    // with slight bias. For details, see:
+                    // https://lemire.me/blog/2016/06/30/fast-random-shuffling
+                    Ok(match (u64::from(<u32 as arbitrary::Arbitrary>::arbitrary(&mut u)?) * #count) >> 32 {
+                        #(#variants_take_rest,)*
+                        _ => unreachable!()
+                    })
+                },
+            );
+
+            quote! {
+                fn arbitrary(u: &mut arbitrary::Unstructured<#lifetime>) -> arbitrary::Result<Self> {
+                    #arbitrary
+                }
+
+                fn arbitrary_take_rest(mut u: arbitrary::Unstructured<#lifetime>) -> arbitrary::Result<Self> {
+                    #arbitrary_take_rest
+                }
+            }
+        }
+    };
+    Ok(output)
+}
+
+fn construct(
+    fields: &Fields,
+    ctor: impl Fn(usize, &Field) -> Result<TokenStream>,
+) -> Result<TokenStream> {
+    let output = match fields {
+        Fields::Named(names) => {
+            let names: Vec<TokenStream> = names
+                .named
+                .iter()
+                .enumerate()
+                .map(|(i, f)| {
+                    let name = f.ident.as_ref().unwrap();
+                    ctor(i, f).map(|ctor| quote! { #name: #ctor })
+                })
+                .collect::<Result<_>>()?;
+            quote! { { #(#names,)* } }
+        }
+        Fields::Unnamed(names) => {
+            let names: Vec<TokenStream> = names
+                .unnamed
+                .iter()
+                .enumerate()
+                .map(|(i, f)| ctor(i, f).map(|ctor| quote! { #ctor }))
+                .collect::<Result<_>>()?;
+            quote! { ( #(#names),* ) }
+        }
+        Fields::Unit => quote!(),
+    };
+    Ok(output)
+}
+
+fn construct_take_rest(fields: &Fields) -> Result<TokenStream> {
+    construct(fields, |idx, field| {
+        determine_field_constructor(field).map(|field_constructor| match field_constructor {
+            FieldConstructor::Default => quote!(Default::default()),
+            FieldConstructor::Arbitrary => {
+                if idx + 1 == fields.len() {
+                    quote! { arbitrary::Arbitrary::arbitrary_take_rest(u)? }
+                } else {
+                    quote! { arbitrary::Arbitrary::arbitrary(&mut u)? }
+                }
+            }
+            FieldConstructor::With(function_or_closure) => quote!((#function_or_closure)(&mut u)?),
+            FieldConstructor::Value(value) => quote!(#value),
+        })
+    })
+}
+
+fn gen_size_hint_method(input: &DeriveInput) -> Result<TokenStream> {
+    let size_hint_fields = |fields: &Fields| {
+        fields
+            .iter()
+            .map(|f| {
+                let ty = &f.ty;
+                determine_field_constructor(f).map(|field_constructor| {
+                    match field_constructor {
+                        FieldConstructor::Default | FieldConstructor::Value(_) => {
+                            quote!((0, Some(0)))
+                        }
+                        FieldConstructor::Arbitrary => {
+                            quote! { <#ty as arbitrary::Arbitrary>::size_hint(depth) }
+                        }
+
+                        // Note that in this case it's hard to determine what size_hint must be, so size_of::<T>() is
+                        // just an educated guess, although it's gonna be inaccurate for dynamically
+                        // allocated types (Vec, HashMap, etc.).
+                        FieldConstructor::With(_) => {
+                            quote! { (::core::mem::size_of::<#ty>(), None) }
+                        }
+                    }
+                })
+            })
+            .collect::<Result<Vec<TokenStream>>>()
+            .map(|hints| {
+                quote! {
+                    arbitrary::size_hint::and_all(&[
+                        #( #hints ),*
+                    ])
+                }
+            })
+    };
+    let size_hint_structlike = |fields: &Fields| {
+        size_hint_fields(fields).map(|hint| {
+            quote! {
+                #[inline]
+                fn size_hint(depth: usize) -> (usize, Option<usize>) {
+                    arbitrary::size_hint::recursion_guard(depth, |depth| #hint)
+                }
+            }
+        })
+    };
+    match &input.data {
+        Data::Struct(data) => size_hint_structlike(&data.fields),
+        Data::Union(data) => size_hint_structlike(&Fields::Named(data.fields.clone())),
+        Data::Enum(data) => data
+            .variants
+            .iter()
+            .map(|v| size_hint_fields(&v.fields))
+            .collect::<Result<Vec<TokenStream>>>()
+            .map(|variants| {
+                quote! {
+                    #[inline]
+                    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+                        arbitrary::size_hint::and(
+                            <u32 as arbitrary::Arbitrary>::size_hint(depth),
+                            arbitrary::size_hint::recursion_guard(depth, |depth| {
+                                arbitrary::size_hint::or_all(&[ #( #variants ),* ])
+                            }),
+                        )
+                    }
+                }
+            }),
+    }
+}
+
+fn gen_constructor_for_field(field: &Field) -> Result<TokenStream> {
+    let ctor = match determine_field_constructor(field)? {
+        FieldConstructor::Default => quote!(Default::default()),
+        FieldConstructor::Arbitrary => quote!(arbitrary::Arbitrary::arbitrary(u)?),
+        FieldConstructor::With(function_or_closure) => quote!((#function_or_closure)(u)?),
+        FieldConstructor::Value(value) => quote!(#value),
+    };
+    Ok(ctor)
+}