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Print safe and explicitly unsafe foreign items
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@dtolnay
dtolnay committed Oct 23, 2024
1 parent 91ebe48 commit db38f77
Showing 1 changed file with 117 additions and 20 deletions.
137 changes: 117 additions & 20 deletions src/item.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -91,7 +91,11 @@ impl Printer {
self.outer_attrs(&item.attrs);
self.cbox(INDENT);
self.visibility(&item.vis);
self.signature(&item.sig);
self.signature(
&item.sig,
#[cfg(feature = "verbatim")]
&verbatim::Safety::Disallowed,
);
self.where_clause_for_body(&item.sig.generics.where_clause);
self.word("{");
self.hardbreak_if_nonempty();
Expand Down Expand Up @@ -794,7 +798,11 @@ impl Printer {
self.outer_attrs(&foreign_item.attrs);
self.cbox(INDENT);
self.visibility(&foreign_item.vis);
self.signature(&foreign_item.sig);
self.signature(
&foreign_item.sig,
#[cfg(feature = "verbatim")]
&verbatim::Safety::Disallowed,
);
self.where_clause_semi(&foreign_item.sig.generics.where_clause);
self.end();
self.hardbreak();
Expand Down Expand Up @@ -844,8 +852,10 @@ impl Printer {
#[cfg(feature = "verbatim")]
fn foreign_item_verbatim(&mut self, tokens: &TokenStream) {
use syn::parse::{Parse, ParseStream, Result};
use syn::{Attribute, Token, Visibility};
use verbatim::{FlexibleItemFn, FlexibleItemStatic, FlexibleItemType, WhereClauseLocation};
use syn::{Abi, Attribute, Token, Visibility};
use verbatim::{
kw, FlexibleItemFn, FlexibleItemStatic, FlexibleItemType, WhereClauseLocation,
};

enum ForeignItemVerbatim {
Empty,
Expand All @@ -855,6 +865,16 @@ impl Printer {
TypeFlexible(FlexibleItemType),
}

fn peek_signature(input: ParseStream) -> bool {
let fork = input.fork();
fork.parse::<Option<Token![const]>>().is_ok()
&& fork.parse::<Option<Token![async]>>().is_ok()
&& ((fork.peek(kw::safe) && fork.parse::<kw::safe>().is_ok())
|| fork.parse::<Option<Token![unsafe]>>().is_ok())
&& fork.parse::<Option<Abi>>().is_ok()
&& fork.peek(Token![fn])
}

impl Parse for ForeignItemVerbatim {
fn parse(input: ParseStream) -> Result<Self> {
if input.is_empty() {
Expand All @@ -869,15 +889,13 @@ impl Printer {
let defaultness = false;

let lookahead = input.lookahead1();
if lookahead.peek(Token![const])
|| lookahead.peek(Token![async])
|| lookahead.peek(Token![unsafe])
|| lookahead.peek(Token![extern])
|| lookahead.peek(Token![fn])
{
if lookahead.peek(Token![fn]) || peek_signature(input) {
let flexible_item = FlexibleItemFn::parse(attrs, vis, defaultness, input)?;
Ok(ForeignItemVerbatim::FnFlexible(flexible_item))
} else if lookahead.peek(Token![static]) {
} else if lookahead.peek(Token![static])
|| ((input.peek(Token![unsafe]) || input.peek(kw::safe))
&& input.peek2(Token![static]))
{
let flexible_item = FlexibleItemStatic::parse(attrs, vis, input)?;
Ok(ForeignItemVerbatim::StaticFlexible(flexible_item))
} else if lookahead.peek(Token![type]) {
Expand Down Expand Up @@ -953,7 +971,11 @@ impl Printer {
fn trait_item_fn(&mut self, trait_item: &TraitItemFn) {
self.outer_attrs(&trait_item.attrs);
self.cbox(INDENT);
self.signature(&trait_item.sig);
self.signature(
&trait_item.sig,
#[cfg(feature = "verbatim")]
&verbatim::Safety::Disallowed,
);
if let Some(block) = &trait_item.default {
self.where_clause_for_body(&trait_item.sig.generics.where_clause);
self.word("{");
Expand Down Expand Up @@ -1149,7 +1171,11 @@ impl Printer {
if impl_item.defaultness.is_some() {
self.word("default ");
}
self.signature(&impl_item.sig);
self.signature(
&impl_item.sig,
#[cfg(feature = "verbatim")]
&verbatim::Safety::Disallowed,
);
self.where_clause_for_body(&impl_item.sig.generics.where_clause);
self.word("{");
self.hardbreak_if_nonempty();
Expand Down Expand Up @@ -1277,15 +1303,32 @@ impl Printer {
}
}

fn signature(&mut self, signature: &Signature) {
fn signature(
&mut self,
signature: &Signature,
#[cfg(feature = "verbatim")] safety: &verbatim::Safety,
) {
if signature.constness.is_some() {
self.word("const ");
}
if signature.asyncness.is_some() {
self.word("async ");
}
if signature.unsafety.is_some() {
self.word("unsafe ");
#[cfg(feature = "verbatim")]
{
if let verbatim::Safety::Disallowed = safety {
if signature.unsafety.is_some() {
self.word("unsafe ");
}
} else {
self.safety(safety);
}
}
#[cfg(not(feature = "verbatim"))]
{
if signature.unsafety.is_some() {
self.word("unsafe ");
}
}
if let Some(abi) = &signature.abi {
self.abi(abi);
Expand Down Expand Up @@ -1381,12 +1424,16 @@ mod verbatim {
use crate::iter::IterDelimited;
use crate::INDENT;
use syn::ext::IdentExt;
use syn::parse::{ParseStream, Result};
use syn::parse::{Parse, ParseStream, Result};
use syn::{
braced, token, Attribute, Block, Expr, Generics, Ident, Signature, StaticMutability, Stmt,
Token, Type, TypeParamBound, Visibility, WhereClause,
};

pub mod kw {
syn::custom_keyword!(safe);
}

pub struct FlexibleItemConst {
pub attrs: Vec<Attribute>,
pub vis: Visibility,
Expand All @@ -1401,13 +1448,15 @@ mod verbatim {
pub attrs: Vec<Attribute>,
pub vis: Visibility,
pub defaultness: bool,
pub safety: Safety,
pub sig: Signature,
pub body: Option<Vec<Stmt>>,
}

pub struct FlexibleItemStatic {
pub attrs: Vec<Attribute>,
pub vis: Visibility,
pub safety: Safety,
pub mutability: StaticMutability,
pub ident: Ident,
pub ty: Option<Type>,
Expand All @@ -1425,6 +1474,13 @@ mod verbatim {
pub where_clause_after_eq: Option<WhereClause>,
}

pub enum Safety {
Unsafe,
Safe,
Default,
Disallowed,
}

pub enum WhereClauseLocation {
// type Ty<T> where T: 'static = T;
BeforeEq,
Expand Down Expand Up @@ -1474,7 +1530,16 @@ mod verbatim {
defaultness: bool,
input: ParseStream,
) -> Result<Self> {
let sig: Signature = input.parse()?;
let constness: Option<Token![const]> = input.parse()?;
let asyncness: Option<Token![async]> = input.parse()?;
let safety: Safety = input.parse()?;

let lookahead = input.lookahead1();
let sig: Signature = if lookahead.peek(Token![extern]) || lookahead.peek(Token![fn]) {
input.parse()?
} else {
return Err(lookahead.error());
};

let lookahead = input.lookahead1();
let body = if lookahead.peek(Token![;]) {
Expand All @@ -1493,14 +1558,21 @@ mod verbatim {
attrs,
vis,
defaultness,
sig,
safety,
sig: Signature {
constness,
asyncness,
unsafety: None,
..sig
},
body,
})
}
}

impl FlexibleItemStatic {
pub fn parse(attrs: Vec<Attribute>, vis: Visibility, input: ParseStream) -> Result<Self> {
let safety: Safety = input.parse()?;
input.parse::<Token![static]>()?;
let mutability: StaticMutability = input.parse()?;
let ident = input.parse()?;
Expand Down Expand Up @@ -1530,6 +1602,7 @@ mod verbatim {
Ok(FlexibleItemStatic {
attrs,
vis,
safety,
mutability,
ident,
ty,
Expand Down Expand Up @@ -1601,6 +1674,20 @@ mod verbatim {
}
}

impl Parse for Safety {
fn parse(input: ParseStream) -> Result<Self> {
if input.peek(Token![unsafe]) {
input.parse::<Token![unsafe]>()?;
Ok(Safety::Unsafe)
} else if input.peek(kw::safe) {
input.parse::<kw::safe>()?;
Ok(Safety::Safe)
} else {
Ok(Safety::Default)
}
}
}

impl Printer {
pub fn flexible_item_const(&mut self, item: &FlexibleItemConst) {
self.outer_attrs(&item.attrs);
Expand Down Expand Up @@ -1635,7 +1722,7 @@ mod verbatim {
if item.defaultness {
self.word("default ");
}
self.signature(&item.sig);
self.signature(&item.sig, &item.safety);
if let Some(body) = &item.body {
self.where_clause_for_body(&item.sig.generics.where_clause);
self.word("{");
Expand All @@ -1658,6 +1745,7 @@ mod verbatim {
self.outer_attrs(&item.attrs);
self.cbox(0);
self.visibility(&item.vis);
self.safety(&item.safety);
self.word("static ");
self.static_mutability(&item.mutability);
self.ident(&item.ident);
Expand Down Expand Up @@ -1708,5 +1796,14 @@ mod verbatim {
self.end();
self.hardbreak();
}

pub fn safety(&mut self, safety: &Safety) {
match safety {
Safety::Unsafe => self.word("unsafe "),
Safety::Safe => self.word("safe "),
Safety::Default => {}
Safety::Disallowed => unreachable!(),
}
}
}
}

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