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proc_macro: Add `Span::mixed_site` exposing `macro_rules` hygiene

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petrochenkov committed Sep 22, 2019
1 parent c6293e3 commit d1310dc6c989e191d85c73c943d4175fbf1dccb8
@@ -148,6 +148,7 @@ macro_rules! with_api {
fn debug($self: $S::Span) -> String;
fn def_site() -> $S::Span;
fn call_site() -> $S::Span;
fn mixed_site() -> $S::Span;
fn source_file($self: $S::Span) -> $S::SourceFile;
fn parent($self: $S::Span) -> Option<$S::Span>;
fn source($self: $S::Span) -> $S::Span;
@@ -271,6 +271,15 @@ impl Span {
Span(bridge::client::Span::call_site())
}

/// A span that represents `macro_rules` hygiene, and sometimes resolves at the macro
/// definition site (local variables, labels, `$crate`) and sometimes at the macro
/// call site (everything else).
/// The span location is taken from the call-site.
#[unstable(feature = "proc_macro_mixed_site", issue = "65049")]
pub fn mixed_site() -> Span {
Span(bridge::client::Span::mixed_site())
}

/// The original source file into which this span points.
#[unstable(feature = "proc_macro_span", issue = "54725")]
pub fn source_file(&self) -> SourceFile {
@@ -953,6 +953,12 @@ impl<'a> ExtCtxt<'a> {
span.with_call_site_ctxt(self.current_expansion.id)
}

/// Equivalent of `Span::mixed_site` from the proc macro API,
/// except that the location is taken from the span passed as an argument.
pub fn with_mixed_site_ctxt(&self, span: Span) -> Span {
span.with_mixed_site_ctxt(self.current_expansion.id)
}

/// Returns span for the macro which originally caused the current expansion to happen.
///
/// Stops backtracing at include! boundary.
@@ -355,6 +355,7 @@ pub(crate) struct Rustc<'a> {
sess: &'a ParseSess,
def_site: Span,
call_site: Span,
mixed_site: Span,
}

impl<'a> Rustc<'a> {
@@ -364,6 +365,7 @@ impl<'a> Rustc<'a> {
sess: cx.parse_sess,
def_site: cx.with_def_site_ctxt(expn_data.def_site),
call_site: cx.with_call_site_ctxt(expn_data.call_site),
mixed_site: cx.with_mixed_site_ctxt(expn_data.call_site),
}
}

@@ -664,6 +666,9 @@ impl server::Span for Rustc<'_> {
fn call_site(&mut self) -> Self::Span {
self.call_site
}
fn mixed_site(&mut self) -> Self::Span {
self.mixed_site
}
fn source_file(&mut self, span: Self::Span) -> Self::SourceFile {
self.sess.source_map().lookup_char_pos(span.lo()).file
}
@@ -526,6 +526,12 @@ impl Span {
self.with_ctxt_from_mark(expn_id, Transparency::Transparent)
}

/// Equivalent of `Span::mixed_site` from the proc macro API,
/// except that the location is taken from the `self` span.
pub fn with_mixed_site_ctxt(&self, expn_id: ExpnId) -> Span {
self.with_ctxt_from_mark(expn_id, Transparency::SemiTransparent)
}

/// Produces a span with the same location as `self` and context produced by a macro with the
/// given ID and transparency, assuming that macro was defined directly and not produced by
/// some other macro (which is the case for built-in and procedural macros).
@@ -0,0 +1,42 @@
// force-host
// no-prefer-dynamic

#![feature(proc_macro_hygiene)]
#![feature(proc_macro_mixed_site)]
#![feature(proc_macro_quote)]

#![crate_type = "proc-macro"]

extern crate proc_macro;
use proc_macro::*;

#[proc_macro]
pub fn proc_macro_rules(input: TokenStream) -> TokenStream {
if input.is_empty() {
let id = |s| TokenTree::from(Ident::new(s, Span::mixed_site()));
let item_def = id("ItemDef");
let local_def = id("local_def");
let item_use = id("ItemUse");
let local_use = id("local_use");
let mut single_quote = Punct::new('\'', Spacing::Joint);
single_quote.set_span(Span::mixed_site());
let label_use: TokenStream = [
TokenTree::from(single_quote),
id("label_use"),
].iter().cloned().collect();
quote!(
struct $item_def;
let $local_def = 0;

$item_use; // OK
$local_use; // ERROR
break $label_use; // ERROR
)
} else {
let mut dollar_crate = input.into_iter().next().unwrap();
dollar_crate.set_span(Span::mixed_site());
quote!(
type A = $dollar_crate::ItemUse;
)
}
}
@@ -59,54 +59,54 @@ PRINT-ATTR RE-COLLECTED (DISPLAY): struct B (identity ! ($crate :: S)) ;
PRINT-ATTR INPUT (DEBUG): TokenStream [
Ident {
ident: "struct",
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
Ident {
ident: "B",
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
Group {
delimiter: Parenthesis,
stream: TokenStream [
Ident {
ident: "identity",
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
Punct {
ch: '!',
spacing: Alone,
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
Group {
delimiter: Parenthesis,
stream: TokenStream [
Ident {
ident: "$crate",
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
Punct {
ch: ':',
spacing: Joint,
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
Punct {
ch: ':',
spacing: Alone,
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
Ident {
ident: "S",
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
],
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
],
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
Punct {
ch: ';',
spacing: Alone,
span: #8 bytes(LO..HI),
span: #10 bytes(LO..HI),
},
]
@@ -124,121 +124,121 @@ PRINT-BANG INPUT (DISPLAY): struct M ($crate :: S) ;
PRINT-BANG INPUT (DEBUG): TokenStream [
Ident {
ident: "struct",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Ident {
ident: "M",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Group {
delimiter: Parenthesis,
stream: TokenStream [
Ident {
ident: "$crate",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Punct {
ch: ':',
spacing: Joint,
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Punct {
ch: ':',
spacing: Alone,
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Ident {
ident: "S",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
],
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Punct {
ch: ';',
spacing: Alone,
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
]
PRINT-ATTR INPUT (DISPLAY): struct A(::dollar_crate_external::S);
PRINT-ATTR RE-COLLECTED (DISPLAY): struct A ($crate :: S) ;
PRINT-ATTR INPUT (DEBUG): TokenStream [
Ident {
ident: "struct",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Ident {
ident: "A",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Group {
delimiter: Parenthesis,
stream: TokenStream [
Ident {
ident: "$crate",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Punct {
ch: ':',
spacing: Joint,
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Punct {
ch: ':',
spacing: Alone,
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Ident {
ident: "S",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
],
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Punct {
ch: ';',
spacing: Alone,
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
]
PRINT-DERIVE INPUT (DISPLAY): struct D(::dollar_crate_external::S);
PRINT-DERIVE RE-COLLECTED (DISPLAY): struct D ($crate :: S) ;
PRINT-DERIVE INPUT (DEBUG): TokenStream [
Ident {
ident: "struct",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Ident {
ident: "D",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Group {
delimiter: Parenthesis,
stream: TokenStream [
Ident {
ident: "$crate",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Punct {
ch: ':',
spacing: Joint,
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Punct {
ch: ':',
spacing: Alone,
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Ident {
ident: "S",
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
],
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
Punct {
ch: ';',
spacing: Alone,
span: #10 bytes(LO..HI),
span: #13 bytes(LO..HI),
},
]
@@ -0,0 +1,26 @@
// Proc macros using `mixed_site` spans exhibit usual properties of `macro_rules` hygiene.

// aux-build:mixed-site-span.rs

#![feature(proc_macro_hygiene)]

#[macro_use]
extern crate mixed_site_span;

struct ItemUse;

fn main() {
'label_use: loop {
let local_use = 1;
proc_macro_rules!();
//~^ ERROR use of undeclared label `'label_use`
//~| ERROR cannot find value `local_use` in this scope
ItemDef; // OK
local_def; //~ ERROR cannot find value `local_def` in this scope
}
}

macro_rules! pass_dollar_crate {
() => (proc_macro_rules!($crate);) //~ ERROR cannot find type `ItemUse` in crate `$crate`
}
pass_dollar_crate!();

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