diff --git a/compiler/rustc_ast/src/tokenstream.rs b/compiler/rustc_ast/src/tokenstream.rs
index b2207f2281620..0550f53a96fb3 100644
--- a/compiler/rustc_ast/src/tokenstream.rs
+++ b/compiler/rustc_ast/src/tokenstream.rs
@@ -44,6 +44,12 @@ pub enum TokenTree {
Delimited(DelimSpan, DelimToken, TokenStream),
}
+#[derive(Copy, Clone)]
+pub enum CanSynthesizeMissingTokens {
+ Yes,
+ No,
+}
+
// Ensure all fields of `TokenTree` is `Send` and `Sync`.
#[cfg(parallel_compiler)]
fn _dummy()
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 2e1b5a74a7b7e..82616c21891bb 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -37,7 +37,7 @@
use rustc_ast::node_id::NodeMap;
use rustc_ast::token::{self, DelimToken, Nonterminal, Token};
-use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree};
+use rustc_ast::tokenstream::{CanSynthesizeMissingTokens, DelimSpan, TokenStream, TokenTree};
use rustc_ast::visit::{self, AssocCtxt, Visitor};
use rustc_ast::walk_list;
use rustc_ast::{self as ast, *};
@@ -206,7 +206,8 @@ pub trait ResolverAstLowering {
) -> LocalDefId;
}
-type NtToTokenstream = fn(&Nonterminal, &ParseSess, Span) -> TokenStream;
+type NtToTokenstream =
+ fn(&Nonterminal, &ParseSess, Span, CanSynthesizeMissingTokens) -> TokenStream;
/// Context of `impl Trait` in code, which determines whether it is allowed in an HIR subtree,
/// and if so, what meaning it has.
@@ -393,6 +394,47 @@ enum AnonymousLifetimeMode {
PassThrough,
}
+struct TokenStreamLowering<'a> {
+ parse_sess: &'a ParseSess,
+ synthesize_tokens: CanSynthesizeMissingTokens,
+ nt_to_tokenstream: NtToTokenstream,
+}
+
+impl<'a> TokenStreamLowering<'a> {
+ fn lower_token_stream(&mut self, tokens: TokenStream) -> TokenStream {
+ tokens.into_trees().flat_map(|tree| self.lower_token_tree(tree).into_trees()).collect()
+ }
+
+ fn lower_token_tree(&mut self, tree: TokenTree) -> TokenStream {
+ match tree {
+ TokenTree::Token(token) => self.lower_token(token),
+ TokenTree::Delimited(span, delim, tts) => {
+ TokenTree::Delimited(span, delim, self.lower_token_stream(tts)).into()
+ }
+ }
+ }
+
+ fn lower_token(&mut self, token: Token) -> TokenStream {
+ match token.kind {
+ token::Interpolated(nt) => {
+ let tts = (self.nt_to_tokenstream)(
+ &nt,
+ self.parse_sess,
+ token.span,
+ self.synthesize_tokens,
+ );
+ TokenTree::Delimited(
+ DelimSpan::from_single(token.span),
+ DelimToken::NoDelim,
+ self.lower_token_stream(tts),
+ )
+ .into()
+ }
+ _ => TokenTree::Token(token).into(),
+ }
+ }
+}
+
struct ImplTraitTypeIdVisitor<'a> {
ids: &'a mut SmallVec<[NodeId; 1]>,
}
@@ -955,40 +997,49 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
match *args {
MacArgs::Empty => MacArgs::Empty,
MacArgs::Delimited(dspan, delim, ref tokens) => {
- MacArgs::Delimited(dspan, delim, self.lower_token_stream(tokens.clone()))
- }
- MacArgs::Eq(eq_span, ref tokens) => {
- MacArgs::Eq(eq_span, self.lower_token_stream(tokens.clone()))
- }
- }
- }
-
- fn lower_token_stream(&mut self, tokens: TokenStream) -> TokenStream {
- tokens.into_trees().flat_map(|tree| self.lower_token_tree(tree).into_trees()).collect()
- }
-
- fn lower_token_tree(&mut self, tree: TokenTree) -> TokenStream {
- match tree {
- TokenTree::Token(token) => self.lower_token(token),
- TokenTree::Delimited(span, delim, tts) => {
- TokenTree::Delimited(span, delim, self.lower_token_stream(tts)).into()
+ // This is either a non-key-value attribute, or a `macro_rules!` body.
+ // We either not have any nonterminals present (in the case of an attribute),
+ // or have tokens available for all nonterminals in the case of a nested
+ // `macro_rules`: e.g:
+ //
+ // ```rust
+ // macro_rules! outer {
+ // ($e:expr) => {
+ // macro_rules! inner {
+ // () => { $e }
+ // }
+ // }
+ // }
+ // ```
+ //
+ // In both cases, we don't want to synthesize any tokens
+ MacArgs::Delimited(
+ dspan,
+ delim,
+ self.lower_token_stream(tokens.clone(), CanSynthesizeMissingTokens::No),
+ )
}
+ // This is an inert key-value attribute - it will never be visible to macros
+ // after it gets lowered to HIR. Therefore, we can synthesize tokens with fake
+ // spans to handle nonterminals in `#[doc]` (e.g. `#[doc = $e]`).
+ MacArgs::Eq(eq_span, ref tokens) => MacArgs::Eq(
+ eq_span,
+ self.lower_token_stream(tokens.clone(), CanSynthesizeMissingTokens::Yes),
+ ),
}
}
- fn lower_token(&mut self, token: Token) -> TokenStream {
- match token.kind {
- token::Interpolated(nt) => {
- let tts = (self.nt_to_tokenstream)(&nt, &self.sess.parse_sess, token.span);
- TokenTree::Delimited(
- DelimSpan::from_single(token.span),
- DelimToken::NoDelim,
- self.lower_token_stream(tts),
- )
- .into()
- }
- _ => TokenTree::Token(token).into(),
+ fn lower_token_stream(
+ &self,
+ tokens: TokenStream,
+ synthesize_tokens: CanSynthesizeMissingTokens,
+ ) -> TokenStream {
+ TokenStreamLowering {
+ parse_sess: &self.sess.parse_sess,
+ synthesize_tokens,
+ nt_to_tokenstream: self.nt_to_tokenstream,
}
+ .lower_token_stream(tokens)
}
/// Given an associated type constraint like one of these:
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index 335f3b7a9a011..774a0764d114f 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -2,8 +2,8 @@ use crate::expand::{self, AstFragment, Invocation};
use crate::module::DirectoryOwnership;
use rustc_ast::ptr::P;
-use rustc_ast::token;
-use rustc_ast::tokenstream::TokenStream;
+use rustc_ast::token::{self, Nonterminal};
+use rustc_ast::tokenstream::{CanSynthesizeMissingTokens, TokenStream};
use rustc_ast::visit::{AssocCtxt, Visitor};
use rustc_ast::{self as ast, Attribute, NodeId, PatKind};
use rustc_attr::{self as attr, Deprecation, HasAttrs, Stability};
@@ -119,8 +119,8 @@ impl Annotatable {
}
}
- crate fn into_tokens(self, sess: &ParseSess) -> TokenStream {
- let nt = match self {
+ crate fn into_nonterminal(self) -> Nonterminal {
+ match self {
Annotatable::Item(item) => token::NtItem(item),
Annotatable::TraitItem(item) | Annotatable::ImplItem(item) => {
token::NtItem(P(item.and_then(ast::AssocItem::into_item)))
@@ -137,8 +137,11 @@ impl Annotatable {
| Annotatable::Param(..)
| Annotatable::StructField(..)
| Annotatable::Variant(..) => panic!("unexpected annotatable"),
- };
- nt_to_tokenstream(&nt, sess, DUMMY_SP)
+ }
+ }
+
+ crate fn into_tokens(self, sess: &ParseSess) -> TokenStream {
+ nt_to_tokenstream(&self.into_nonterminal(), sess, DUMMY_SP, CanSynthesizeMissingTokens::No)
}
pub fn expect_item(self) -> P<ast::Item> {
diff --git a/compiler/rustc_expand/src/config.rs b/compiler/rustc_expand/src/config.rs
index 563783c5b795d..1193f66651ce9 100644
--- a/compiler/rustc_expand/src/config.rs
+++ b/compiler/rustc_expand/src/config.rs
@@ -29,6 +29,7 @@ use smallvec::SmallVec;
pub struct StripUnconfigured<'a> {
pub sess: &'a Session,
pub features: Option<&'a Features>,
+ pub modified: bool,
}
fn get_features(
@@ -199,7 +200,7 @@ fn get_features(
// `cfg_attr`-process the crate's attributes and compute the crate's features.
pub fn features(sess: &Session, mut krate: ast::Crate) -> (ast::Crate, Features) {
- let mut strip_unconfigured = StripUnconfigured { sess, features: None };
+ let mut strip_unconfigured = StripUnconfigured { sess, features: None, modified: false };
let unconfigured_attrs = krate.attrs.clone();
let diag = &sess.parse_sess.span_diagnostic;
@@ -243,7 +244,12 @@ const CFG_ATTR_NOTE_REF: &str = "for more information, visit \
impl<'a> StripUnconfigured<'a> {
pub fn configure<T: HasAttrs>(&mut self, mut node: T) -> Option<T> {
self.process_cfg_attrs(&mut node);
- self.in_cfg(node.attrs()).then_some(node)
+ if self.in_cfg(node.attrs()) {
+ Some(node)
+ } else {
+ self.modified = true;
+ None
+ }
}
/// Parse and expand all `cfg_attr` attributes into a list of attributes
@@ -270,6 +276,9 @@ impl<'a> StripUnconfigured<'a> {
return vec![attr];
}
+ // A `#[cfg_attr]` either gets removed, or replaced with a new attribute
+ self.modified = true;
+
let (cfg_predicate, expanded_attrs) = match self.parse_cfg_attr(&attr) {
None => return vec![],
Some(r) => r,
diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs
index 2da5bde028fc1..5d40d478b963d 100644
--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@@ -12,7 +12,7 @@ use rustc_ast::ptr::P;
use rustc_ast::token;
use rustc_ast::tokenstream::TokenStream;
use rustc_ast::visit::{self, AssocCtxt, Visitor};
-use rustc_ast::{self as ast, AttrItem, Block, LitKind, NodeId, PatKind, Path};
+use rustc_ast::{self as ast, AttrItem, AttrStyle, Block, LitKind, NodeId, PatKind, Path};
use rustc_ast::{ItemKind, MacArgs, MacCallStmt, MacStmtStyle, StmtKind, Unsafe};
use rustc_ast_pretty::pprust;
use rustc_attr::{self as attr, is_builtin_attr, HasAttrs};
@@ -522,12 +522,29 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
item.visit_attrs(|attrs| attrs.retain(|a| !a.has_name(sym::derive)));
(item, Vec::new())
} else {
- let mut item = StripUnconfigured {
+ let mut visitor = StripUnconfigured {
sess: self.cx.sess,
features: self.cx.ecfg.features,
- }
- .fully_configure(item);
+ modified: false,
+ };
+ let mut item = visitor.fully_configure(item);
item.visit_attrs(|attrs| attrs.retain(|a| !a.has_name(sym::derive)));
+ if visitor.modified && !derives.is_empty() {
+ // Erase the tokens if cfg-stripping modified the item
+ // This will cause us to synthesize fake tokens
+ // when `nt_to_tokenstream` is called on this item.
+ match &mut item {
+ Annotatable::Item(item) => item.tokens = None,
+ Annotatable::Stmt(stmt) => {
+ if let StmtKind::Item(item) = &mut stmt.kind {
+ item.tokens = None
+ } else {
+ panic!("Unexpected stmt {:?}", stmt);
+ }
+ }
+ _ => panic!("Unexpected annotatable {:?}", item),
+ }
+ }
invocations.reserve(derives.len());
let derive_placeholders = derives
@@ -622,7 +639,11 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
let invocations = {
let mut collector = InvocationCollector {
- cfg: StripUnconfigured { sess: &self.cx.sess, features: self.cx.ecfg.features },
+ cfg: StripUnconfigured {
+ sess: &self.cx.sess,
+ features: self.cx.ecfg.features,
+ modified: false,
+ },
cx: self.cx,
invocations: Vec::new(),
monotonic: self.monotonic,
@@ -716,7 +737,15 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
SyntaxExtensionKind::Attr(expander) => {
self.gate_proc_macro_input(&item);
self.gate_proc_macro_attr_item(span, &item);
- let tokens = item.into_tokens(&self.cx.sess.parse_sess);
+ let tokens = match attr.style {
+ AttrStyle::Outer => item.into_tokens(&self.cx.sess.parse_sess),
+ // FIXME: Properly collect tokens for inner attributes
+ AttrStyle::Inner => rustc_parse::fake_token_stream(
+ &self.cx.sess.parse_sess,
+ &item.into_nonterminal(),
+ span,
+ ),
+ };
let attr_item = attr.unwrap_normal_item();
if let MacArgs::Eq(..) = attr_item.args {
self.cx.span_err(span, "key-value macro attributes are not supported");
diff --git a/compiler/rustc_expand/src/proc_macro.rs b/compiler/rustc_expand/src/proc_macro.rs
index 36707a1ae272d..e8e098b621295 100644
--- a/compiler/rustc_expand/src/proc_macro.rs
+++ b/compiler/rustc_expand/src/proc_macro.rs
@@ -3,7 +3,7 @@ use crate::proc_macro_server;
use rustc_ast::ptr::P;
use rustc_ast::token;
-use rustc_ast::tokenstream::{TokenStream, TokenTree};
+use rustc_ast::tokenstream::{CanSynthesizeMissingTokens, TokenStream, TokenTree};
use rustc_ast::{self as ast, *};
use rustc_data_structures::sync::Lrc;
use rustc_errors::{struct_span_err, Applicability, ErrorReported};
@@ -94,7 +94,12 @@ impl MultiItemModifier for ProcMacroDerive {
let input = if item.pretty_printing_compatibility_hack() {
TokenTree::token(token::Interpolated(Lrc::new(item)), DUMMY_SP).into()
} else {
- nt_to_tokenstream(&item, &ecx.sess.parse_sess, DUMMY_SP)
+ nt_to_tokenstream(
+ &item,
+ &ecx.sess.parse_sess,
+ DUMMY_SP,
+ CanSynthesizeMissingTokens::Yes,
+ )
};
let server = proc_macro_server::Rustc::new(ecx);
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index 4cfb188783ba1..02ae842675f37 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -2,7 +2,8 @@ use crate::base::ExtCtxt;
use rustc_ast as ast;
use rustc_ast::token;
-use rustc_ast::tokenstream::{self, DelimSpan, Spacing::*, TokenStream, TreeAndSpacing};
+use rustc_ast::tokenstream::{self, CanSynthesizeMissingTokens};
+use rustc_ast::tokenstream::{DelimSpan, Spacing::*, TokenStream, TreeAndSpacing};
use rustc_ast_pretty::pprust;
use rustc_data_structures::sync::Lrc;
use rustc_errors::Diagnostic;
@@ -178,7 +179,7 @@ impl FromInternal<(TreeAndSpacing, &'_ ParseSess, &'_ mut Vec<Self>)>
{
TokenTree::Ident(Ident::new(sess, name.name, is_raw, name.span))
} else {
- let stream = nt_to_tokenstream(&nt, sess, span);
+ let stream = nt_to_tokenstream(&nt, sess, span, CanSynthesizeMissingTokens::No);
TokenTree::Group(Group {
delimiter: Delimiter::None,
stream,
diff --git a/compiler/rustc_parse/src/lib.rs b/compiler/rustc_parse/src/lib.rs
index 44999c9b63ab6..9abffbacfc3b3 100644
--- a/compiler/rustc_parse/src/lib.rs
+++ b/compiler/rustc_parse/src/lib.rs
@@ -7,22 +7,18 @@
use rustc_ast as ast;
use rustc_ast::attr::HasAttrs;
-use rustc_ast::token::{self, DelimToken, Nonterminal, Token, TokenKind};
-use rustc_ast::tokenstream::{self, LazyTokenStream, TokenStream, TokenTree};
+use rustc_ast::token::{self, Nonterminal};
+use rustc_ast::tokenstream::{self, CanSynthesizeMissingTokens, LazyTokenStream, TokenStream};
use rustc_ast_pretty::pprust;
-use rustc_data_structures::fx::FxHashSet;
use rustc_data_structures::sync::Lrc;
use rustc_errors::{Diagnostic, FatalError, Level, PResult};
use rustc_session::parse::ParseSess;
-use rustc_span::{symbol::kw, FileName, SourceFile, Span, DUMMY_SP};
+use rustc_span::{FileName, SourceFile, Span};
-use smallvec::SmallVec;
-use std::cell::RefCell;
-use std::mem;
use std::path::Path;
use std::str;
-use tracing::{debug, info};
+use tracing::debug;
pub const MACRO_ARGUMENTS: Option<&str> = Some("macro arguments");
@@ -237,7 +233,12 @@ pub fn parse_in<'a, T>(
// NOTE(Centril): The following probably shouldn't be here but it acknowledges the
// fact that architecturally, we are using parsing (read on below to understand why).
-pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> TokenStream {
+pub fn nt_to_tokenstream(
+ nt: &Nonterminal,
+ sess: &ParseSess,
+ span: Span,
+ synthesize_tokens: CanSynthesizeMissingTokens,
+) -> TokenStream {
// A `Nonterminal` is often a parsed AST item. At this point we now
// need to convert the parsed AST to an actual token stream, e.g.
// un-parse it basically.
@@ -255,9 +256,11 @@ pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> Toke
|tokens: Option<&LazyTokenStream>| tokens.as_ref().map(|t| t.create_token_stream());
let tokens = match *nt {
- Nonterminal::NtItem(ref item) => prepend_attrs(&item.attrs, item.tokens.as_ref()),
+ Nonterminal::NtItem(ref item) => {
+ prepend_attrs(sess, &item.attrs, nt, span, item.tokens.as_ref())
+ }
Nonterminal::NtBlock(ref block) => convert_tokens(block.tokens.as_ref()),
- Nonterminal::NtStmt(ref stmt) => prepend_attrs(stmt.attrs(), stmt.tokens()),
+ Nonterminal::NtStmt(ref stmt) => prepend_attrs(sess, stmt.attrs(), nt, span, stmt.tokens()),
Nonterminal::NtPat(ref pat) => convert_tokens(pat.tokens.as_ref()),
Nonterminal::NtTy(ref ty) => convert_tokens(ty.tokens.as_ref()),
Nonterminal::NtIdent(ident, is_raw) => {
@@ -274,376 +277,45 @@ pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> Toke
if expr.tokens.is_none() {
debug!("missing tokens for expr {:?}", expr);
}
- prepend_attrs(&expr.attrs, expr.tokens.as_ref())
+ prepend_attrs(sess, &expr.attrs, nt, span, expr.tokens.as_ref())
}
};
- // Caches the stringification of 'good' `TokenStreams` which passed
- // `tokenstream_probably_equal_for_proc_macro`. This allows us to avoid
- // repeatedly stringifying and comparing the same `TokenStream` for deeply
- // nested nonterminals.
- //
- // We cache by the strinification instead of the `TokenStream` to avoid
- // needing to implement `Hash` for `TokenStream`. Note that it's possible to
- // have two distinct `TokenStream`s that stringify to the same result
- // (e.g. if they differ only in hygiene information). However, any
- // information lost during the stringification process is also intentionally
- // ignored by `tokenstream_probably_equal_for_proc_macro`, so it's fine
- // that a single cache entry may 'map' to multiple distinct `TokenStream`s.
- //
- // This is a temporary hack to prevent compilation blowup on certain inputs.
- // The entire pretty-print/retokenize process will be removed soon.
- thread_local! {
- static GOOD_TOKEN_CACHE: RefCell<FxHashSet<String>> = Default::default();
- }
-
- // FIXME(#43081): Avoid this pretty-print + reparse hack
- // Pretty-print the AST struct without inserting any parenthesis
- // beyond those explicitly written by the user (e.g. `ExpnKind::Paren`).
- // The resulting stream may have incorrect precedence, but it's only
- // ever used for a comparison against the capture tokenstream.
- let source = pprust::nonterminal_to_string_no_extra_parens(nt);
- let filename = FileName::macro_expansion_source_code(&source);
- let reparsed_tokens = parse_stream_from_source_str(filename, source.clone(), sess, Some(span));
-
- // During early phases of the compiler the AST could get modified
- // directly (e.g., attributes added or removed) and the internal cache
- // of tokens my not be invalidated or updated. Consequently if the
- // "lossless" token stream disagrees with our actual stringification
- // (which has historically been much more battle-tested) then we go
- // with the lossy stream anyway (losing span information).
- //
- // Note that the comparison isn't `==` here to avoid comparing spans,
- // but it *also* is a "probable" equality which is a pretty weird
- // definition. We mostly want to catch actual changes to the AST
- // like a `#[cfg]` being processed or some weird `macro_rules!`
- // expansion.
- //
- // What we *don't* want to catch is the fact that a user-defined
- // literal like `0xf` is stringified as `15`, causing the cached token
- // stream to not be literal `==` token-wise (ignoring spans) to the
- // token stream we got from stringification.
- //
- // Instead the "probably equal" check here is "does each token
- // recursively have the same discriminant?" We basically don't look at
- // the token values here and assume that such fine grained token stream
- // modifications, including adding/removing typically non-semantic
- // tokens such as extra braces and commas, don't happen.
if let Some(tokens) = tokens {
- if GOOD_TOKEN_CACHE.with(|cache| cache.borrow().contains(&source)) {
- return tokens;
- }
-
- // Compare with a non-relaxed delim match to start.
- if tokenstream_probably_equal_for_proc_macro(&tokens, &reparsed_tokens, sess, false) {
- GOOD_TOKEN_CACHE.with(|cache| cache.borrow_mut().insert(source.clone()));
- return tokens;
- }
-
- // The check failed. This time, we pretty-print the AST struct with parenthesis
- // inserted to preserve precedence. This may cause `None`-delimiters in the captured
- // token stream to match up with inserted parenthesis in the reparsed stream.
- let source_with_parens = pprust::nonterminal_to_string(nt);
- let filename_with_parens = FileName::macro_expansion_source_code(&source_with_parens);
-
- if GOOD_TOKEN_CACHE.with(|cache| cache.borrow().contains(&source_with_parens)) {
- return tokens;
- }
-
- let reparsed_tokens_with_parens = parse_stream_from_source_str(
- filename_with_parens,
- source_with_parens,
- sess,
- Some(span),
- );
-
- // Compare with a relaxed delim match - we want inserted parenthesis in the
- // reparsed stream to match `None`-delimiters in the original stream.
- if tokenstream_probably_equal_for_proc_macro(
- &tokens,
- &reparsed_tokens_with_parens,
- sess,
- true,
- ) {
- GOOD_TOKEN_CACHE.with(|cache| cache.borrow_mut().insert(source.clone()));
- return tokens;
- }
-
- info!(
- "cached tokens found, but they're not \"probably equal\", \
- going with stringified version"
- );
- info!("cached tokens: {}", pprust::tts_to_string(&tokens));
- info!("reparsed tokens: {}", pprust::tts_to_string(&reparsed_tokens_with_parens));
-
- info!("cached tokens debug: {:?}", tokens);
- info!("reparsed tokens debug: {:?}", reparsed_tokens_with_parens);
- }
- reparsed_tokens
-}
-
-// See comments in `Nonterminal::to_tokenstream` for why we care about
-// *probably* equal here rather than actual equality
-//
-// This is otherwise the same as `eq_unspanned`, only recursing with a
-// different method.
-pub fn tokenstream_probably_equal_for_proc_macro(
- tokens: &TokenStream,
- reparsed_tokens: &TokenStream,
- sess: &ParseSess,
- relaxed_delim_match: bool,
-) -> bool {
- // When checking for `probably_eq`, we ignore certain tokens that aren't
- // preserved in the AST. Because they are not preserved, the pretty
- // printer arbitrarily adds or removes them when printing as token
- // streams, making a comparison between a token stream generated from an
- // AST and a token stream which was parsed into an AST more reliable.
- fn semantic_tree(tree: &TokenTree) -> bool {
- if let TokenTree::Token(token) = tree {
- if let
- // The pretty printer tends to add trailing commas to
- // everything, and in particular, after struct fields.
- | token::Comma
- // The pretty printer collapses many semicolons into one.
- | token::Semi
- // We don't preserve leading `|` tokens in patterns, so
- // we ignore them entirely
- | token::BinOp(token::BinOpToken::Or)
- // We don't preserve trailing '+' tokens in trait bounds,
- // so we ignore them entirely
- | token::BinOp(token::BinOpToken::Plus)
- // The pretty printer can turn `$crate` into `::crate_name`
- | token::ModSep = token.kind {
- return false;
- }
- }
- true
- }
-
- // When comparing two `TokenStream`s, we ignore the `IsJoint` information.
- //
- // However, `rustc_parse::lexer::tokentrees::TokenStreamBuilder` will
- // use `Token.glue` on adjacent tokens with the proper `IsJoint`.
- // Since we are ignoreing `IsJoint`, a 'glued' token (e.g. `BinOp(Shr)`)
- // and its 'split'/'unglued' compoenents (e.g. `Gt, Gt`) are equivalent
- // when determining if two `TokenStream`s are 'probably equal'.
- //
- // Therefore, we use `break_two_token_op` to convert all tokens
- // to the 'unglued' form (if it exists). This ensures that two
- // `TokenStream`s which differ only in how their tokens are glued
- // will be considered 'probably equal', which allows us to keep spans.
- //
- // This is important when the original `TokenStream` contained
- // extra spaces (e.g. `f :: < Vec < _ > > ( ) ;'). These extra spaces
- // will be omitted when we pretty-print, which can cause the original
- // and reparsed `TokenStream`s to differ in the assignment of `IsJoint`,
- // leading to some tokens being 'glued' together in one stream but not
- // the other. See #68489 for more details.
- fn break_tokens(tree: TokenTree) -> impl Iterator<Item = TokenTree> {
- // In almost all cases, we should have either zero or one levels
- // of 'unglueing'. However, in some unusual cases, we may need
- // to iterate breaking tokens mutliple times. For example:
- // '[BinOpEq(Shr)] => [Gt, Ge] -> [Gt, Gt, Eq]'
- let mut token_trees: SmallVec<[_; 2]>;
- if let TokenTree::Token(token) = tree {
- let mut out = SmallVec::<[_; 2]>::new();
- out.push(token);
- // Iterate to fixpoint:
- // * We start off with 'out' containing our initial token, and `temp` empty
- // * If we are able to break any tokens in `out`, then `out` will have
- // at least one more element than 'temp', so we will try to break tokens
- // again.
- // * If we cannot break any tokens in 'out', we are done
- loop {
- let mut temp = SmallVec::<[_; 2]>::new();
- let mut changed = false;
-
- for token in out.into_iter() {
- if let Some((first, second)) = token.kind.break_two_token_op() {
- temp.push(Token::new(first, DUMMY_SP));
- temp.push(Token::new(second, DUMMY_SP));
- changed = true;
- } else {
- temp.push(token);
- }
- }
- out = temp;
- if !changed {
- break;
- }
- }
- token_trees = out.into_iter().map(TokenTree::Token).collect();
- } else {
- token_trees = SmallVec::new();
- token_trees.push(tree);
- }
- token_trees.into_iter()
- }
-
- fn expand_token(tree: TokenTree, sess: &ParseSess) -> impl Iterator<Item = TokenTree> {
- // When checking tokenstreams for 'probable equality', we are comparing
- // a captured (from parsing) `TokenStream` to a reparsed tokenstream.
- // The reparsed Tokenstream will never have `None`-delimited groups,
- // since they are only ever inserted as a result of macro expansion.
- // Therefore, inserting a `None`-delimtied group here (when we
- // convert a nested `Nonterminal` to a tokenstream) would cause
- // a mismatch with the reparsed tokenstream.
- //
- // Note that we currently do not handle the case where the
- // reparsed stream has a `Parenthesis`-delimited group
- // inserted. This will cause a spurious mismatch:
- // issue #75734 tracks resolving this.
-
- let expanded: SmallVec<[_; 1]> =
- if let TokenTree::Token(Token { kind: TokenKind::Interpolated(nt), span }) = &tree {
- nt_to_tokenstream(nt, sess, *span)
- .into_trees()
- .flat_map(|t| expand_token(t, sess))
- .collect()
- } else {
- // Filter before and after breaking tokens,
- // since we may want to ignore both glued and unglued tokens.
- std::iter::once(tree)
- .filter(semantic_tree)
- .flat_map(break_tokens)
- .filter(semantic_tree)
- .collect()
- };
- expanded.into_iter()
- }
-
- // Break tokens after we expand any nonterminals, so that we break tokens
- // that are produced as a result of nonterminal expansion.
- let tokens = tokens.trees().flat_map(|t| expand_token(t, sess));
- let reparsed_tokens = reparsed_tokens.trees().flat_map(|t| expand_token(t, sess));
-
- tokens.eq_by(reparsed_tokens, |t, rt| {
- tokentree_probably_equal_for_proc_macro(&t, &rt, sess, relaxed_delim_match)
- })
-}
-
-// See comments in `Nonterminal::to_tokenstream` for why we care about
-// *probably* equal here rather than actual equality
-//
-// This is otherwise the same as `eq_unspanned`, only recursing with a
-// different method.
-pub fn tokentree_probably_equal_for_proc_macro(
- token: &TokenTree,
- reparsed_token: &TokenTree,
- sess: &ParseSess,
- relaxed_delim_match: bool,
-) -> bool {
- match (token, reparsed_token) {
- (TokenTree::Token(token), TokenTree::Token(reparsed_token)) => {
- token_probably_equal_for_proc_macro(token, reparsed_token)
- }
- (
- TokenTree::Delimited(_, delim, tokens),
- TokenTree::Delimited(_, reparsed_delim, reparsed_tokens),
- ) if delim == reparsed_delim => tokenstream_probably_equal_for_proc_macro(
- tokens,
- reparsed_tokens,
- sess,
- relaxed_delim_match,
- ),
- (TokenTree::Delimited(_, DelimToken::NoDelim, tokens), reparsed_token) => {
- if relaxed_delim_match {
- if let TokenTree::Delimited(_, DelimToken::Paren, reparsed_tokens) = reparsed_token
- {
- if tokenstream_probably_equal_for_proc_macro(
- tokens,
- reparsed_tokens,
- sess,
- relaxed_delim_match,
- ) {
- return true;
- }
- }
- }
- tokens.len() == 1
- && tokentree_probably_equal_for_proc_macro(
- &tokens.trees().next().unwrap(),
- reparsed_token,
- sess,
- relaxed_delim_match,
- )
- }
- _ => false,
+ return tokens;
+ } else if matches!(synthesize_tokens, CanSynthesizeMissingTokens::Yes) {
+ return fake_token_stream(sess, nt, span);
+ } else {
+ let pretty = rustc_ast_pretty::pprust::nonterminal_to_string_no_extra_parens(&nt);
+ panic!("Missing tokens at {:?} for nt {:?}", span, pretty);
}
}
-// See comments in `Nonterminal::to_tokenstream` for why we care about
-// *probably* equal here rather than actual equality
-fn token_probably_equal_for_proc_macro(first: &Token, other: &Token) -> bool {
- if mem::discriminant(&first.kind) != mem::discriminant(&other.kind) {
- return false;
- }
- use rustc_ast::token::TokenKind::*;
- match (&first.kind, &other.kind) {
- (&Eq, &Eq)
- | (&Lt, &Lt)
- | (&Le, &Le)
- | (&EqEq, &EqEq)
- | (&Ne, &Ne)
- | (&Ge, &Ge)
- | (&Gt, &Gt)
- | (&AndAnd, &AndAnd)
- | (&OrOr, &OrOr)
- | (&Not, &Not)
- | (&Tilde, &Tilde)
- | (&At, &At)
- | (&Dot, &Dot)
- | (&DotDot, &DotDot)
- | (&DotDotDot, &DotDotDot)
- | (&DotDotEq, &DotDotEq)
- | (&Comma, &Comma)
- | (&Semi, &Semi)
- | (&Colon, &Colon)
- | (&ModSep, &ModSep)
- | (&RArrow, &RArrow)
- | (&LArrow, &LArrow)
- | (&FatArrow, &FatArrow)
- | (&Pound, &Pound)
- | (&Dollar, &Dollar)
- | (&Question, &Question)
- | (&Eof, &Eof) => true,
-
- (&BinOp(a), &BinOp(b)) | (&BinOpEq(a), &BinOpEq(b)) => a == b,
-
- (&OpenDelim(a), &OpenDelim(b)) | (&CloseDelim(a), &CloseDelim(b)) => a == b,
-
- (&DocComment(a1, a2, a3), &DocComment(b1, b2, b3)) => a1 == b1 && a2 == b2 && a3 == b3,
-
- (&Literal(a), &Literal(b)) => a == b,
-
- (&Lifetime(a), &Lifetime(b)) => a == b,
- (&Ident(a, b), &Ident(c, d)) => {
- b == d && (a == c || a == kw::DollarCrate || c == kw::DollarCrate)
- }
-
- (&Interpolated(..), &Interpolated(..)) => panic!("Unexpanded Interpolated!"),
-
- _ => panic!("forgot to add a token?"),
- }
+pub fn fake_token_stream(sess: &ParseSess, nt: &Nonterminal, span: Span) -> TokenStream {
+ let source = pprust::nonterminal_to_string(nt);
+ let filename = FileName::macro_expansion_source_code(&source);
+ parse_stream_from_source_str(filename, source, sess, Some(span))
}
fn prepend_attrs(
+ sess: &ParseSess,
attrs: &[ast::Attribute],
+ nt: &Nonterminal,
+ span: Span,
tokens: Option<&tokenstream::LazyTokenStream>,
) -> Option<tokenstream::TokenStream> {
- let tokens = tokens?.create_token_stream();
if attrs.is_empty() {
- return Some(tokens);
+ return Some(tokens?.create_token_stream());
}
let mut builder = tokenstream::TokenStreamBuilder::new();
for attr in attrs {
// FIXME: Correctly handle tokens for inner attributes.
// For now, we fall back to reparsing the original AST node
if attr.style == ast::AttrStyle::Inner {
- return None;
+ return Some(fake_token_stream(sess, nt, span));
}
builder.push(attr.tokens());
}
- builder.push(tokens);
+ builder.push(tokens?.create_token_stream());
Some(builder.build())
}