rust/compiler/rustc_expand/src/proc_macro_server.rs
Nika Layzell 64a7d57046 review changes
longer names for RPC generics and reduced dependency on macros in the server.
2022-06-28 09:54:29 -04:00

820 lines
29 KiB
Rust

use crate::base::ExtCtxt;
use rustc_ast as ast;
use rustc_ast::token;
use rustc_ast::tokenstream::{self, Spacing::*, TokenStream};
use rustc_ast_pretty::pprust;
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::sync::Lrc;
use rustc_errors::{Diagnostic, MultiSpan, PResult};
use rustc_parse::lexer::nfc_normalize;
use rustc_parse::parse_stream_from_source_str;
use rustc_session::parse::ParseSess;
use rustc_span::def_id::CrateNum;
use rustc_span::symbol::{self, kw, sym, Symbol};
use rustc_span::{BytePos, FileName, Pos, SourceFile, Span};
use pm::bridge::{server, DelimSpan, ExpnGlobals, Group, Punct, TokenTree};
use pm::{Delimiter, Level, LineColumn};
use std::ops::Bound;
use std::{ascii, panic};
trait FromInternal<T> {
fn from_internal(x: T) -> Self;
}
trait ToInternal<T> {
fn to_internal(self) -> T;
}
impl FromInternal<token::Delimiter> for Delimiter {
fn from_internal(delim: token::Delimiter) -> Delimiter {
match delim {
token::Delimiter::Parenthesis => Delimiter::Parenthesis,
token::Delimiter::Brace => Delimiter::Brace,
token::Delimiter::Bracket => Delimiter::Bracket,
token::Delimiter::Invisible => Delimiter::None,
}
}
}
impl ToInternal<token::Delimiter> for Delimiter {
fn to_internal(self) -> token::Delimiter {
match self {
Delimiter::Parenthesis => token::Delimiter::Parenthesis,
Delimiter::Brace => token::Delimiter::Brace,
Delimiter::Bracket => token::Delimiter::Bracket,
Delimiter::None => token::Delimiter::Invisible,
}
}
}
impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)>
for Vec<TokenTree<TokenStream, Span, Ident, Literal>>
{
fn from_internal((stream, rustc): (TokenStream, &mut Rustc<'_, '_>)) -> Self {
use rustc_ast::token::*;
// Estimate the capacity as `stream.len()` rounded up to the next power
// of two to limit the number of required reallocations.
let mut trees = Vec::with_capacity(stream.len().next_power_of_two());
let mut cursor = stream.into_trees();
while let Some((tree, spacing)) = cursor.next_with_spacing() {
let joint = spacing == Joint;
let Token { kind, span } = match tree {
tokenstream::TokenTree::Delimited(span, delim, tts) => {
let delimiter = pm::Delimiter::from_internal(delim);
trees.push(TokenTree::Group(Group {
delimiter,
stream: Some(tts),
span: DelimSpan {
open: span.open,
close: span.close,
entire: span.entire(),
},
}));
continue;
}
tokenstream::TokenTree::Token(token) => token,
};
let mut op = |s: &str| {
assert!(s.is_ascii());
trees.extend(s.as_bytes().iter().enumerate().map(|(idx, &ch)| {
TokenTree::Punct(Punct { ch, joint: joint || idx != s.len() - 1, span })
}));
};
match kind {
Eq => op("="),
Lt => op("<"),
Le => op("<="),
EqEq => op("=="),
Ne => op("!="),
Ge => op(">="),
Gt => op(">"),
AndAnd => op("&&"),
OrOr => op("||"),
Not => op("!"),
Tilde => op("~"),
BinOp(Plus) => op("+"),
BinOp(Minus) => op("-"),
BinOp(Star) => op("*"),
BinOp(Slash) => op("/"),
BinOp(Percent) => op("%"),
BinOp(Caret) => op("^"),
BinOp(And) => op("&"),
BinOp(Or) => op("|"),
BinOp(Shl) => op("<<"),
BinOp(Shr) => op(">>"),
BinOpEq(Plus) => op("+="),
BinOpEq(Minus) => op("-="),
BinOpEq(Star) => op("*="),
BinOpEq(Slash) => op("/="),
BinOpEq(Percent) => op("%="),
BinOpEq(Caret) => op("^="),
BinOpEq(And) => op("&="),
BinOpEq(Or) => op("|="),
BinOpEq(Shl) => op("<<="),
BinOpEq(Shr) => op(">>="),
At => op("@"),
Dot => op("."),
DotDot => op(".."),
DotDotDot => op("..."),
DotDotEq => op("..="),
Comma => op(","),
Semi => op(";"),
Colon => op(":"),
ModSep => op("::"),
RArrow => op("->"),
LArrow => op("<-"),
FatArrow => op("=>"),
Pound => op("#"),
Dollar => op("$"),
Question => op("?"),
SingleQuote => op("'"),
Ident(name, false) if name == kw::DollarCrate => trees.push(TokenTree::Ident(Ident::dollar_crate(span))),
Ident(name, is_raw) => trees.push(TokenTree::Ident(Ident::new(rustc.sess(), name, is_raw, span))),
Lifetime(name) => {
let ident = symbol::Ident::new(name, span).without_first_quote();
trees.extend([
TokenTree::Punct(Punct { ch: b'\'', joint: true, span }),
TokenTree::Ident(Ident::new(rustc.sess(), ident.name, false, span)),
]);
}
Literal(lit) => trees.push(TokenTree::Literal(self::Literal { lit, span })),
DocComment(_, attr_style, data) => {
let mut escaped = String::new();
for ch in data.as_str().chars() {
escaped.extend(ch.escape_debug());
}
let stream = [
Ident(sym::doc, false),
Eq,
TokenKind::lit(token::Str, Symbol::intern(&escaped), None),
]
.into_iter()
.map(|kind| tokenstream::TokenTree::token(kind, span))
.collect();
trees.push(TokenTree::Punct(Punct { ch: b'#', joint: false, span }));
if attr_style == ast::AttrStyle::Inner {
trees.push(TokenTree::Punct(Punct { ch: b'!', joint: false, span }));
}
trees.push(TokenTree::Group(Group {
delimiter: pm::Delimiter::Bracket,
stream: Some(stream),
span: DelimSpan::from_single(span),
}));
}
Interpolated(nt) if let NtIdent(ident, is_raw) = *nt => {
trees.push(TokenTree::Ident(Ident::new(rustc.sess(), ident.name, is_raw, ident.span)))
}
Interpolated(nt) => {
let stream = TokenStream::from_nonterminal_ast(&nt);
// A hack used to pass AST fragments to attribute and derive
// macros as a single nonterminal token instead of a token
// stream. Such token needs to be "unwrapped" and not
// represented as a delimited group.
// FIXME: It needs to be removed, but there are some
// compatibility issues (see #73345).
if crate::base::nt_pretty_printing_compatibility_hack(&nt, rustc.sess()) {
trees.extend(Self::from_internal((stream, rustc)));
} else {
trees.push(TokenTree::Group(Group {
delimiter: pm::Delimiter::None,
stream: Some(stream),
span: DelimSpan::from_single(span),
}))
}
}
OpenDelim(..) | CloseDelim(..) => unreachable!(),
Eof => unreachable!(),
}
}
trees
}
}
impl ToInternal<TokenStream> for TokenTree<TokenStream, Span, Ident, Literal> {
fn to_internal(self) -> TokenStream {
use rustc_ast::token::*;
let (ch, joint, span) = match self {
TokenTree::Punct(Punct { ch, joint, span }) => (ch, joint, span),
TokenTree::Group(Group { delimiter, stream, span: DelimSpan { open, close, .. } }) => {
return tokenstream::TokenTree::Delimited(
tokenstream::DelimSpan { open, close },
delimiter.to_internal(),
stream.unwrap_or_default(),
)
.into();
}
TokenTree::Ident(self::Ident { sym, is_raw, span }) => {
return tokenstream::TokenTree::token(Ident(sym, is_raw), span).into();
}
TokenTree::Literal(self::Literal {
lit: token::Lit { kind: token::Integer, symbol, suffix },
span,
}) if symbol.as_str().starts_with('-') => {
let minus = BinOp(BinOpToken::Minus);
let symbol = Symbol::intern(&symbol.as_str()[1..]);
let integer = TokenKind::lit(token::Integer, symbol, suffix);
let a = tokenstream::TokenTree::token(minus, span);
let b = tokenstream::TokenTree::token(integer, span);
return [a, b].into_iter().collect();
}
TokenTree::Literal(self::Literal {
lit: token::Lit { kind: token::Float, symbol, suffix },
span,
}) if symbol.as_str().starts_with('-') => {
let minus = BinOp(BinOpToken::Minus);
let symbol = Symbol::intern(&symbol.as_str()[1..]);
let float = TokenKind::lit(token::Float, symbol, suffix);
let a = tokenstream::TokenTree::token(minus, span);
let b = tokenstream::TokenTree::token(float, span);
return [a, b].into_iter().collect();
}
TokenTree::Literal(self::Literal { lit, span }) => {
return tokenstream::TokenTree::token(Literal(lit), span).into();
}
};
let kind = match ch {
b'=' => Eq,
b'<' => Lt,
b'>' => Gt,
b'!' => Not,
b'~' => Tilde,
b'+' => BinOp(Plus),
b'-' => BinOp(Minus),
b'*' => BinOp(Star),
b'/' => BinOp(Slash),
b'%' => BinOp(Percent),
b'^' => BinOp(Caret),
b'&' => BinOp(And),
b'|' => BinOp(Or),
b'@' => At,
b'.' => Dot,
b',' => Comma,
b';' => Semi,
b':' => Colon,
b'#' => Pound,
b'$' => Dollar,
b'?' => Question,
b'\'' => SingleQuote,
_ => unreachable!(),
};
let tree = tokenstream::TokenTree::token(kind, span);
TokenStream::new(vec![(tree, if joint { Joint } else { Alone })])
}
}
impl ToInternal<rustc_errors::Level> for Level {
fn to_internal(self) -> rustc_errors::Level {
match self {
Level::Error => rustc_errors::Level::Error { lint: false },
Level::Warning => rustc_errors::Level::Warning(None),
Level::Note => rustc_errors::Level::Note,
Level::Help => rustc_errors::Level::Help,
_ => unreachable!("unknown proc_macro::Level variant: {:?}", self),
}
}
}
pub struct FreeFunctions;
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
pub struct Ident {
sym: Symbol,
is_raw: bool,
span: Span,
}
impl Ident {
fn new(sess: &ParseSess, sym: Symbol, is_raw: bool, span: Span) -> Ident {
let sym = nfc_normalize(sym.as_str());
let string = sym.as_str();
if !rustc_lexer::is_ident(string) {
panic!("`{:?}` is not a valid identifier", string)
}
if is_raw && !sym.can_be_raw() {
panic!("`{}` cannot be a raw identifier", string);
}
sess.symbol_gallery.insert(sym, span);
Ident { sym, is_raw, span }
}
fn dollar_crate(span: Span) -> Ident {
// `$crate` is accepted as an ident only if it comes from the compiler.
Ident { sym: kw::DollarCrate, is_raw: false, span }
}
}
// FIXME(eddyb) `Literal` should not expose internal `Debug` impls.
#[derive(Clone, Debug)]
pub struct Literal {
lit: token::Lit,
span: Span,
}
pub(crate) struct Rustc<'a, 'b> {
ecx: &'a mut ExtCtxt<'b>,
def_site: Span,
call_site: Span,
mixed_site: Span,
krate: CrateNum,
rebased_spans: FxHashMap<usize, Span>,
}
impl<'a, 'b> Rustc<'a, 'b> {
pub fn new(ecx: &'a mut ExtCtxt<'b>) -> Self {
let expn_data = ecx.current_expansion.id.expn_data();
Rustc {
def_site: ecx.with_def_site_ctxt(expn_data.def_site),
call_site: ecx.with_call_site_ctxt(expn_data.call_site),
mixed_site: ecx.with_mixed_site_ctxt(expn_data.call_site),
krate: expn_data.macro_def_id.unwrap().krate,
rebased_spans: FxHashMap::default(),
ecx,
}
}
fn sess(&self) -> &ParseSess {
self.ecx.parse_sess()
}
fn lit(&mut self, kind: token::LitKind, symbol: Symbol, suffix: Option<Symbol>) -> Literal {
Literal { lit: token::Lit::new(kind, symbol, suffix), span: self.call_site }
}
}
impl server::Types for Rustc<'_, '_> {
type FreeFunctions = FreeFunctions;
type TokenStream = TokenStream;
type Ident = Ident;
type Literal = Literal;
type SourceFile = Lrc<SourceFile>;
type MultiSpan = Vec<Span>;
type Diagnostic = Diagnostic;
type Span = Span;
}
impl server::FreeFunctions for Rustc<'_, '_> {
fn track_env_var(&mut self, var: &str, value: Option<&str>) {
self.sess()
.env_depinfo
.borrow_mut()
.insert((Symbol::intern(var), value.map(Symbol::intern)));
}
fn track_path(&mut self, path: &str) {
self.sess().file_depinfo.borrow_mut().insert(Symbol::intern(path));
}
}
impl server::TokenStream for Rustc<'_, '_> {
fn is_empty(&mut self, stream: &Self::TokenStream) -> bool {
stream.is_empty()
}
fn from_str(&mut self, src: &str) -> Self::TokenStream {
parse_stream_from_source_str(
FileName::proc_macro_source_code(src),
src.to_string(),
self.sess(),
Some(self.call_site),
)
}
fn to_string(&mut self, stream: &Self::TokenStream) -> String {
pprust::tts_to_string(stream)
}
fn expand_expr(&mut self, stream: &Self::TokenStream) -> Result<Self::TokenStream, ()> {
// Parse the expression from our tokenstream.
let expr: PResult<'_, _> = try {
let mut p = rustc_parse::stream_to_parser(
self.sess(),
stream.clone(),
Some("proc_macro expand expr"),
);
let expr = p.parse_expr()?;
if p.token != token::Eof {
p.unexpected()?;
}
expr
};
let expr = expr.map_err(|mut err| {
err.emit();
})?;
// Perform eager expansion on the expression.
let expr = self
.ecx
.expander()
.fully_expand_fragment(crate::expand::AstFragment::Expr(expr))
.make_expr();
// NOTE: For now, limit `expand_expr` to exclusively expand to literals.
// This may be relaxed in the future.
// We don't use `TokenStream::from_ast` as the tokenstream currently cannot
// be recovered in the general case.
match &expr.kind {
ast::ExprKind::Lit(l) => {
Ok(tokenstream::TokenTree::token(token::Literal(l.token), l.span).into())
}
ast::ExprKind::Unary(ast::UnOp::Neg, e) => match &e.kind {
ast::ExprKind::Lit(l) => match l.token {
token::Lit { kind: token::Integer | token::Float, .. } => {
Ok(Self::TokenStream::from_iter([
// FIXME: The span of the `-` token is lost when
// parsing, so we cannot faithfully recover it here.
tokenstream::TokenTree::token(token::BinOp(token::Minus), e.span),
tokenstream::TokenTree::token(token::Literal(l.token), l.span),
]))
}
_ => Err(()),
},
_ => Err(()),
},
_ => Err(()),
}
}
fn from_token_tree(
&mut self,
tree: TokenTree<Self::TokenStream, Self::Span, Self::Ident, Self::Literal>,
) -> Self::TokenStream {
tree.to_internal()
}
fn concat_trees(
&mut self,
base: Option<Self::TokenStream>,
trees: Vec<TokenTree<Self::TokenStream, Self::Span, Self::Ident, Self::Literal>>,
) -> Self::TokenStream {
let mut builder = tokenstream::TokenStreamBuilder::new();
if let Some(base) = base {
builder.push(base);
}
for tree in trees {
builder.push(tree.to_internal());
}
builder.build()
}
fn concat_streams(
&mut self,
base: Option<Self::TokenStream>,
streams: Vec<Self::TokenStream>,
) -> Self::TokenStream {
let mut builder = tokenstream::TokenStreamBuilder::new();
if let Some(base) = base {
builder.push(base);
}
for stream in streams {
builder.push(stream);
}
builder.build()
}
fn into_trees(
&mut self,
stream: Self::TokenStream,
) -> Vec<TokenTree<Self::TokenStream, Self::Span, Self::Ident, Self::Literal>> {
FromInternal::from_internal((stream, self))
}
}
impl server::Ident for Rustc<'_, '_> {
fn new(&mut self, string: &str, span: Self::Span, is_raw: bool) -> Self::Ident {
Ident::new(self.sess(), Symbol::intern(string), is_raw, span)
}
fn span(&mut self, ident: Self::Ident) -> Self::Span {
ident.span
}
fn with_span(&mut self, ident: Self::Ident, span: Self::Span) -> Self::Ident {
Ident { span, ..ident }
}
}
impl server::Literal for Rustc<'_, '_> {
fn from_str(&mut self, s: &str) -> Result<Self::Literal, ()> {
let name = FileName::proc_macro_source_code(s);
let mut parser = rustc_parse::new_parser_from_source_str(self.sess(), name, s.to_owned());
let first_span = parser.token.span.data();
let minus_present = parser.eat(&token::BinOp(token::Minus));
let lit_span = parser.token.span.data();
let token::Literal(mut lit) = parser.token.kind else {
return Err(());
};
// Check no comment or whitespace surrounding the (possibly negative)
// literal, or more tokens after it.
if (lit_span.hi.0 - first_span.lo.0) as usize != s.len() {
return Err(());
}
if minus_present {
// If minus is present, check no comment or whitespace in between it
// and the literal token.
if first_span.hi.0 != lit_span.lo.0 {
return Err(());
}
// Check literal is a kind we allow to be negated in a proc macro token.
match lit.kind {
token::LitKind::Bool
| token::LitKind::Byte
| token::LitKind::Char
| token::LitKind::Str
| token::LitKind::StrRaw(_)
| token::LitKind::ByteStr
| token::LitKind::ByteStrRaw(_)
| token::LitKind::Err => return Err(()),
token::LitKind::Integer | token::LitKind::Float => {}
}
// Synthesize a new symbol that includes the minus sign.
let symbol = Symbol::intern(&s[..1 + lit.symbol.as_str().len()]);
lit = token::Lit::new(lit.kind, symbol, lit.suffix);
}
Ok(Literal { lit, span: self.call_site })
}
fn to_string(&mut self, literal: &Self::Literal) -> String {
literal.lit.to_string()
}
fn debug_kind(&mut self, literal: &Self::Literal) -> String {
format!("{:?}", literal.lit.kind)
}
fn symbol(&mut self, literal: &Self::Literal) -> String {
literal.lit.symbol.to_string()
}
fn suffix(&mut self, literal: &Self::Literal) -> Option<String> {
literal.lit.suffix.as_ref().map(Symbol::to_string)
}
fn integer(&mut self, n: &str) -> Self::Literal {
self.lit(token::Integer, Symbol::intern(n), None)
}
fn typed_integer(&mut self, n: &str, kind: &str) -> Self::Literal {
self.lit(token::Integer, Symbol::intern(n), Some(Symbol::intern(kind)))
}
fn float(&mut self, n: &str) -> Self::Literal {
self.lit(token::Float, Symbol::intern(n), None)
}
fn f32(&mut self, n: &str) -> Self::Literal {
self.lit(token::Float, Symbol::intern(n), Some(sym::f32))
}
fn f64(&mut self, n: &str) -> Self::Literal {
self.lit(token::Float, Symbol::intern(n), Some(sym::f64))
}
fn string(&mut self, string: &str) -> Self::Literal {
let quoted = format!("{:?}", string);
assert!(quoted.starts_with('"') && quoted.ends_with('"'));
let symbol = &quoted[1..quoted.len() - 1];
self.lit(token::Str, Symbol::intern(symbol), None)
}
fn character(&mut self, ch: char) -> Self::Literal {
let quoted = format!("{:?}", ch);
assert!(quoted.starts_with('\'') && quoted.ends_with('\''));
let symbol = &quoted[1..quoted.len() - 1];
self.lit(token::Char, Symbol::intern(symbol), None)
}
fn byte_string(&mut self, bytes: &[u8]) -> Self::Literal {
let string = bytes
.iter()
.cloned()
.flat_map(ascii::escape_default)
.map(Into::<char>::into)
.collect::<String>();
self.lit(token::ByteStr, Symbol::intern(&string), None)
}
fn span(&mut self, literal: &Self::Literal) -> Self::Span {
literal.span
}
fn set_span(&mut self, literal: &mut Self::Literal, span: Self::Span) {
literal.span = span;
}
fn subspan(
&mut self,
literal: &Self::Literal,
start: Bound<usize>,
end: Bound<usize>,
) -> Option<Self::Span> {
let span = literal.span;
let length = span.hi().to_usize() - span.lo().to_usize();
let start = match start {
Bound::Included(lo) => lo,
Bound::Excluded(lo) => lo.checked_add(1)?,
Bound::Unbounded => 0,
};
let end = match end {
Bound::Included(hi) => hi.checked_add(1)?,
Bound::Excluded(hi) => hi,
Bound::Unbounded => length,
};
// Bounds check the values, preventing addition overflow and OOB spans.
if start > u32::MAX as usize
|| end > u32::MAX as usize
|| (u32::MAX - start as u32) < span.lo().to_u32()
|| (u32::MAX - end as u32) < span.lo().to_u32()
|| start >= end
|| end > length
{
return None;
}
let new_lo = span.lo() + BytePos::from_usize(start);
let new_hi = span.lo() + BytePos::from_usize(end);
Some(span.with_lo(new_lo).with_hi(new_hi))
}
}
impl server::SourceFile for Rustc<'_, '_> {
fn eq(&mut self, file1: &Self::SourceFile, file2: &Self::SourceFile) -> bool {
Lrc::ptr_eq(file1, file2)
}
fn path(&mut self, file: &Self::SourceFile) -> String {
match file.name {
FileName::Real(ref name) => name
.local_path()
.expect("attempting to get a file path in an imported file in `proc_macro::SourceFile::path`")
.to_str()
.expect("non-UTF8 file path in `proc_macro::SourceFile::path`")
.to_string(),
_ => file.name.prefer_local().to_string(),
}
}
fn is_real(&mut self, file: &Self::SourceFile) -> bool {
file.is_real_file()
}
}
impl server::MultiSpan for Rustc<'_, '_> {
fn new(&mut self) -> Self::MultiSpan {
vec![]
}
fn push(&mut self, spans: &mut Self::MultiSpan, span: Self::Span) {
spans.push(span)
}
}
impl server::Diagnostic for Rustc<'_, '_> {
fn new(&mut self, level: Level, msg: &str, spans: Self::MultiSpan) -> Self::Diagnostic {
let mut diag = Diagnostic::new(level.to_internal(), msg);
diag.set_span(MultiSpan::from_spans(spans));
diag
}
fn sub(
&mut self,
diag: &mut Self::Diagnostic,
level: Level,
msg: &str,
spans: Self::MultiSpan,
) {
diag.sub(level.to_internal(), msg, MultiSpan::from_spans(spans), None);
}
fn emit(&mut self, mut diag: Self::Diagnostic) {
self.sess().span_diagnostic.emit_diagnostic(&mut diag);
}
}
impl server::Span for Rustc<'_, '_> {
fn debug(&mut self, span: Self::Span) -> String {
if self.ecx.ecfg.span_debug {
format!("{:?}", span)
} else {
format!("{:?} bytes({}..{})", span.ctxt(), span.lo().0, span.hi().0)
}
}
fn source_file(&mut self, span: Self::Span) -> Self::SourceFile {
self.sess().source_map().lookup_char_pos(span.lo()).file
}
fn parent(&mut self, span: Self::Span) -> Option<Self::Span> {
span.parent_callsite()
}
fn source(&mut self, span: Self::Span) -> Self::Span {
span.source_callsite()
}
fn start(&mut self, span: Self::Span) -> LineColumn {
let loc = self.sess().source_map().lookup_char_pos(span.lo());
LineColumn { line: loc.line, column: loc.col.to_usize() }
}
fn end(&mut self, span: Self::Span) -> LineColumn {
let loc = self.sess().source_map().lookup_char_pos(span.hi());
LineColumn { line: loc.line, column: loc.col.to_usize() }
}
fn before(&mut self, span: Self::Span) -> Self::Span {
span.shrink_to_lo()
}
fn after(&mut self, span: Self::Span) -> Self::Span {
span.shrink_to_hi()
}
fn join(&mut self, first: Self::Span, second: Self::Span) -> Option<Self::Span> {
let self_loc = self.sess().source_map().lookup_char_pos(first.lo());
let other_loc = self.sess().source_map().lookup_char_pos(second.lo());
if self_loc.file.name != other_loc.file.name {
return None;
}
Some(first.to(second))
}
fn resolved_at(&mut self, span: Self::Span, at: Self::Span) -> Self::Span {
span.with_ctxt(at.ctxt())
}
fn source_text(&mut self, span: Self::Span) -> Option<String> {
self.sess().source_map().span_to_snippet(span).ok()
}
/// Saves the provided span into the metadata of
/// *the crate we are currently compiling*, which must
/// be a proc-macro crate. This id can be passed to
/// `recover_proc_macro_span` when our current crate
/// is *run* as a proc-macro.
///
/// Let's suppose that we have two crates - `my_client`
/// and `my_proc_macro`. The `my_proc_macro` crate
/// contains a procedural macro `my_macro`, which
/// is implemented as: `quote! { "hello" }`
///
/// When we *compile* `my_proc_macro`, we will execute
/// the `quote` proc-macro. This will save the span of
/// "hello" into the metadata of `my_proc_macro`. As a result,
/// the body of `my_proc_macro` (after expansion) will end
/// up containing a call that looks like this:
/// `proc_macro::Ident::new("hello", proc_macro::Span::recover_proc_macro_span(0))`
///
/// where `0` is the id returned by this function.
/// When `my_proc_macro` *executes* (during the compilation of `my_client`),
/// the call to `recover_proc_macro_span` will load the corresponding
/// span from the metadata of `my_proc_macro` (which we have access to,
/// since we've loaded `my_proc_macro` from disk in order to execute it).
/// In this way, we have obtained a span pointing into `my_proc_macro`
fn save_span(&mut self, span: Self::Span) -> usize {
self.sess().save_proc_macro_span(span)
}
fn recover_proc_macro_span(&mut self, id: usize) -> Self::Span {
let (resolver, krate, def_site) = (&*self.ecx.resolver, self.krate, self.def_site);
*self.rebased_spans.entry(id).or_insert_with(|| {
// FIXME: `SyntaxContext` for spans from proc macro crates is lost during encoding,
// replace it with a def-site context until we are encoding it properly.
resolver.get_proc_macro_quoted_span(krate, id).with_ctxt(def_site.ctxt())
})
}
}
impl server::Server for Rustc<'_, '_> {
fn globals(&mut self) -> ExpnGlobals<Self::Span> {
ExpnGlobals {
def_site: self.def_site,
call_site: self.call_site,
mixed_site: self.mixed_site,
}
}
}