use rustc_ast_pretty::pprust;
use rustc_attr::{self as attr, TransparencyError};
use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
-use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, DiagnosticMessage};
+use rustc_errors::{
+ Applicability, Diagnostic, DiagnosticBuilder, DiagnosticMessage, ErrorGuaranteed,
+};
use rustc_feature::Features;
use rustc_lint_defs::builtin::{
RUST_2021_INCOMPATIBLE_OR_PATTERNS, SEMICOLON_IN_EXPRESSIONS_FROM_MACROS,
use std::collections::hash_map::Entry;
use std::{mem, slice};
+use super::macro_parser::{NamedMatches, NamedParseResult};
+
pub(crate) struct ParserAnyMacro<'a> {
parser: Parser<'a>,
cx_expansions.entry(sp).or_default().push(message);
}
+pub(super) trait Tracker<'matcher> {
+ /// This is called before trying to match next MatcherLoc on the current token.
+ fn before_match_loc(&mut self, parser: &TtParser, matcher: &'matcher MatcherLoc);
+
+ /// This is called after an arm has been parsed, either successfully or unsuccessfully. When this is called,
+ /// `before_match_loc` was called at least once (with a `MatcherLoc::Eof`).
+ fn after_arm(&mut self, result: &NamedParseResult);
+
+ /// For tracing.
+ fn description() -> &'static str;
+}
+
+/// A noop tracker that is used in the hot path of the expansion, has zero overhead thanks to monomorphization.
+struct NoopTracker;
+
+impl<'matcher> Tracker<'matcher> for NoopTracker {
+ fn before_match_loc(&mut self, _: &TtParser, _: &'matcher MatcherLoc) {}
+ fn after_arm(&mut self, _: &NamedParseResult) {}
+ fn description() -> &'static str {
+ "none"
+ }
+}
+
/// Expands the rules based macro defined by `lhses` and `rhses` for a given
/// input `arg`.
+#[instrument(skip(cx, transparency, arg, lhses, rhses))]
fn expand_macro<'cx>(
cx: &'cx mut ExtCtxt<'_>,
sp: Span,
trace_macros_note(&mut cx.expansions, sp, msg);
}
- // Which arm's failure should we report? (the one furthest along)
- let mut best_failure: Option<(Token, &str)> = None;
+ // Track nothing for the best performance.
+ let try_success_result = try_match_macro(sess, name, &arg, lhses, &mut NoopTracker);
+
+ match try_success_result {
+ Ok((i, named_matches)) => {
+ let (rhs, rhs_span): (&mbe::Delimited, DelimSpan) = match &rhses[i] {
+ mbe::TokenTree::Delimited(span, delimited) => (&delimited, *span),
+ _ => cx.span_bug(sp, "malformed macro rhs"),
+ };
+ let arm_span = rhses[i].span();
+
+ let rhs_spans = rhs.tts.iter().map(|t| t.span()).collect::<Vec<_>>();
+ // rhs has holes ( `$id` and `$(...)` that need filled)
+ let mut tts = match transcribe(cx, &named_matches, &rhs, rhs_span, transparency) {
+ Ok(tts) => tts,
+ Err(mut err) => {
+ err.emit();
+ return DummyResult::any(arm_span);
+ }
+ };
+
+ // Replace all the tokens for the corresponding positions in the macro, to maintain
+ // proper positions in error reporting, while maintaining the macro_backtrace.
+ if rhs_spans.len() == tts.len() {
+ tts = tts.map_enumerated(|i, tt| {
+ let mut tt = tt.clone();
+ let mut sp = rhs_spans[i];
+ sp = sp.with_ctxt(tt.span().ctxt());
+ tt.set_span(sp);
+ tt
+ });
+ }
+
+ if cx.trace_macros() {
+ let msg = format!("to `{}`", pprust::tts_to_string(&tts));
+ trace_macros_note(&mut cx.expansions, sp, msg);
+ }
+
+ let mut p = Parser::new(sess, tts, false, None);
+ p.last_type_ascription = cx.current_expansion.prior_type_ascription;
+
+ if is_local {
+ cx.resolver.record_macro_rule_usage(node_id, i);
+ }
+
+ // Let the context choose how to interpret the result.
+ // Weird, but useful for X-macros.
+ return Box::new(ParserAnyMacro {
+ parser: p,
+
+ // Pass along the original expansion site and the name of the macro
+ // so we can print a useful error message if the parse of the expanded
+ // macro leaves unparsed tokens.
+ site_span: sp,
+ macro_ident: name,
+ lint_node_id: cx.current_expansion.lint_node_id,
+ is_trailing_mac: cx.current_expansion.is_trailing_mac,
+ arm_span,
+ is_local,
+ });
+ }
+ Err(CanRetry::No(_)) => {
+ debug!("Will not retry matching as an error was emitted already");
+ return DummyResult::any(sp);
+ }
+ Err(CanRetry::Yes) => {
+ // Retry and emit a better error below.
+ }
+ }
+
+ // An error occurred, try the expansion again, tracking the expansion closely for better diagnostics.
+ let mut tracker = CollectTrackerAndEmitter::new(cx, sp);
+
+ let try_success_result = try_match_macro(sess, name, &arg, lhses, &mut tracker);
+ assert!(try_success_result.is_err(), "Macro matching returned a success on the second try");
+
+ if let Some(result) = tracker.result {
+ // An irrecoverable error occurred and has been emitted.
+ return result;
+ }
+
+ let Some((token, label)) = tracker.best_failure else {
+ return tracker.result.expect("must have encountered Error or ErrorReported");
+ };
+
+ let span = token.span.substitute_dummy(sp);
+
+ let mut err = cx.struct_span_err(span, &parse_failure_msg(&token));
+ err.span_label(span, label);
+ if !def_span.is_dummy() && !cx.source_map().is_imported(def_span) {
+ err.span_label(cx.source_map().guess_head_span(def_span), "when calling this macro");
+ }
+
+ annotate_doc_comment(&mut err, sess.source_map(), span);
+
+ // Check whether there's a missing comma in this macro call, like `println!("{}" a);`
+ if let Some((arg, comma_span)) = arg.add_comma() {
+ for lhs in lhses {
+ let parser = parser_from_cx(sess, arg.clone());
+ let mut tt_parser = TtParser::new(name);
+
+ if let Success(_) =
+ tt_parser.parse_tt(&mut Cow::Borrowed(&parser), lhs, &mut NoopTracker)
+ {
+ if comma_span.is_dummy() {
+ err.note("you might be missing a comma");
+ } else {
+ err.span_suggestion_short(
+ comma_span,
+ "missing comma here",
+ ", ",
+ Applicability::MachineApplicable,
+ );
+ }
+ }
+ }
+ }
+ err.emit();
+ cx.trace_macros_diag();
+ DummyResult::any(sp)
+}
+
+/// The tracker used for the slow error path that collects useful info for diagnostics.
+struct CollectTrackerAndEmitter<'a, 'cx> {
+ cx: &'a mut ExtCtxt<'cx>,
+ /// Which arm's failure should we report? (the one furthest along)
+ best_failure: Option<(Token, &'static str)>,
+ root_span: Span,
+ result: Option<Box<dyn MacResult + 'cx>>,
+}
+
+impl<'a, 'cx, 'matcher> Tracker<'matcher> for CollectTrackerAndEmitter<'a, 'cx> {
+ fn before_match_loc(&mut self, _parser: &TtParser, _matcher: &'matcher MatcherLoc) {
+ // Empty for now.
+ }
+
+ fn after_arm(&mut self, result: &NamedParseResult) {
+ match result {
+ Success(_) => {
+ unreachable!("should not collect detailed info for successful macro match");
+ }
+ Failure(token, msg) => match self.best_failure {
+ Some((ref best_token, _)) if best_token.span.lo() >= token.span.lo() => {}
+ _ => self.best_failure = Some((token.clone(), msg)),
+ },
+ Error(err_sp, msg) => {
+ let span = err_sp.substitute_dummy(self.root_span);
+ self.cx.struct_span_err(span, msg).emit();
+ self.result = Some(DummyResult::any(span));
+ }
+ ErrorReported(_) => self.result = Some(DummyResult::any(self.root_span)),
+ }
+ }
+
+ fn description() -> &'static str {
+ "detailed"
+ }
+}
+
+impl<'a, 'cx> CollectTrackerAndEmitter<'a, 'cx> {
+ fn new(cx: &'a mut ExtCtxt<'cx>, root_span: Span) -> Self {
+ Self { cx, best_failure: None, root_span, result: None }
+ }
+}
+
+enum CanRetry {
+ Yes,
+ /// We are not allowed to retry macro expansion as a fatal error has been emitted already.
+ No(ErrorGuaranteed),
+}
+/// Try expanding the macro. Returns the index of the successful arm and its named_matches if it was successful,
+/// and nothing if it failed. On failure, it's the callers job to use `track` accordingly to record all errors
+/// correctly.
+#[instrument(level = "debug", skip(sess, arg, lhses, track), fields(tracking = %T::description()))]
+fn try_match_macro<'matcher, T: Tracker<'matcher>>(
+ sess: &ParseSess,
+ name: Ident,
+ arg: &TokenStream,
+ lhses: &'matcher [Vec<MatcherLoc>],
+ track: &mut T,
+) -> Result<(usize, NamedMatches), CanRetry> {
// We create a base parser that can be used for the "black box" parts.
// Every iteration needs a fresh copy of that parser. However, the parser
// is not mutated on many of the iterations, particularly when dealing with
// this situation.)
// FIXME(Nilstrieb): Stop recovery from happening on this parser and retry later with recovery if the macro failed to match.
let parser = parser_from_cx(sess, arg.clone());
-
// Try each arm's matchers.
let mut tt_parser = TtParser::new(name);
for (i, lhs) in lhses.iter().enumerate() {
+ let _tracing_span = trace_span!("Matching arm", %i);
+
// Take a snapshot of the state of pre-expansion gating at this point.
// This is used so that if a matcher is not `Success(..)`ful,
// then the spans which became gated when parsing the unsuccessful matcher
// are not recorded. On the first `Success(..)`ful matcher, the spans are merged.
let mut gated_spans_snapshot = mem::take(&mut *sess.gated_spans.spans.borrow_mut());
- match tt_parser.parse_tt(&mut Cow::Borrowed(&parser), lhs) {
+ let result = tt_parser.parse_tt(&mut Cow::Borrowed(&parser), lhs, track);
+
+ track.after_arm(&result);
+
+ match result {
Success(named_matches) => {
+ debug!("Parsed arm successfully");
// The matcher was `Success(..)`ful.
// Merge the gated spans from parsing the matcher with the pre-existing ones.
sess.gated_spans.merge(gated_spans_snapshot);
- let (rhs, rhs_span): (&mbe::Delimited, DelimSpan) = match &rhses[i] {
- mbe::TokenTree::Delimited(span, delimited) => (&delimited, *span),
- _ => cx.span_bug(sp, "malformed macro rhs"),
- };
- let arm_span = rhses[i].span();
-
- let rhs_spans = rhs.tts.iter().map(|t| t.span()).collect::<Vec<_>>();
- // rhs has holes ( `$id` and `$(...)` that need filled)
- let mut tts = match transcribe(cx, &named_matches, &rhs, rhs_span, transparency) {
- Ok(tts) => tts,
- Err(mut err) => {
- err.emit();
- return DummyResult::any(arm_span);
- }
- };
-
- // Replace all the tokens for the corresponding positions in the macro, to maintain
- // proper positions in error reporting, while maintaining the macro_backtrace.
- if rhs_spans.len() == tts.len() {
- tts = tts.map_enumerated(|i, tt| {
- let mut tt = tt.clone();
- let mut sp = rhs_spans[i];
- sp = sp.with_ctxt(tt.span().ctxt());
- tt.set_span(sp);
- tt
- });
- }
-
- if cx.trace_macros() {
- let msg = format!("to `{}`", pprust::tts_to_string(&tts));
- trace_macros_note(&mut cx.expansions, sp, msg);
- }
-
- let mut p = Parser::new(sess, tts, false, None);
- p.last_type_ascription = cx.current_expansion.prior_type_ascription;
-
- if is_local {
- cx.resolver.record_macro_rule_usage(node_id, i);
- }
-
- // Let the context choose how to interpret the result.
- // Weird, but useful for X-macros.
- return Box::new(ParserAnyMacro {
- parser: p,
-
- // Pass along the original expansion site and the name of the macro
- // so we can print a useful error message if the parse of the expanded
- // macro leaves unparsed tokens.
- site_span: sp,
- macro_ident: name,
- lint_node_id: cx.current_expansion.lint_node_id,
- is_trailing_mac: cx.current_expansion.is_trailing_mac,
- arm_span,
- is_local,
- });
+ return Ok((i, named_matches));
}
- Failure(token, msg) => match best_failure {
- Some((ref best_token, _)) if best_token.span.lo() >= token.span.lo() => {}
- _ => best_failure = Some((token, msg)),
- },
- Error(err_sp, ref msg) => {
- let span = err_sp.substitute_dummy(sp);
- cx.struct_span_err(span, &msg).emit();
- return DummyResult::any(span);
+ Failure(_, _) => {
+ trace!("Failed to match arm, trying the next one");
+ // Try the next arm.
+ }
+ Error(_, _) => {
+ debug!("Fatal error occurred during matching");
+ // We haven't emitted an error yet, so we can retry.
+ return Err(CanRetry::Yes);
+ }
+ ErrorReported(guarantee) => {
+ debug!("Fatal error occurred and was reported during matching");
+ // An error has been reported already, we cannot retry as that would cause duplicate errors.
+ return Err(CanRetry::No(guarantee));
}
- ErrorReported => return DummyResult::any(sp),
}
// The matcher was not `Success(..)`ful.
// Restore to the state before snapshotting and maybe try again.
mem::swap(&mut gated_spans_snapshot, &mut sess.gated_spans.spans.borrow_mut());
}
- drop(parser);
- let (token, label) = best_failure.expect("ran no matchers");
- let span = token.span.substitute_dummy(sp);
- let mut err = cx.struct_span_err(span, &parse_failure_msg(&token));
- err.span_label(span, label);
- if !def_span.is_dummy() && !cx.source_map().is_imported(def_span) {
- err.span_label(cx.source_map().guess_head_span(def_span), "when calling this macro");
- }
- annotate_doc_comment(&mut err, sess.source_map(), span);
- // Check whether there's a missing comma in this macro call, like `println!("{}" a);`
- if let Some((arg, comma_span)) = arg.add_comma() {
- for lhs in lhses {
- let parser = parser_from_cx(sess, arg.clone());
- if let Success(_) = tt_parser.parse_tt(&mut Cow::Borrowed(&parser), lhs) {
- if comma_span.is_dummy() {
- err.note("you might be missing a comma");
- } else {
- err.span_suggestion_short(
- comma_span,
- "missing comma here",
- ", ",
- Applicability::MachineApplicable,
- );
- }
- }
- }
- }
- err.emit();
- cx.trace_macros_diag();
- DummyResult::any(sp)
+ Err(CanRetry::Yes)
}
// Note that macro-by-example's input is also matched against a token tree:
let parser = Parser::new(&sess.parse_sess, body, true, rustc_parse::MACRO_ARGUMENTS);
let mut tt_parser =
TtParser::new(Ident::with_dummy_span(if macro_rules { kw::MacroRules } else { kw::Macro }));
- let argument_map = match tt_parser.parse_tt(&mut Cow::Borrowed(&parser), &argument_gram) {
- Success(m) => m,
- Failure(token, msg) => {
- let s = parse_failure_msg(&token);
- let sp = token.span.substitute_dummy(def.span);
- let mut err = sess.parse_sess.span_diagnostic.struct_span_err(sp, &s);
- err.span_label(sp, msg);
- annotate_doc_comment(&mut err, sess.source_map(), sp);
- err.emit();
- return dummy_syn_ext();
- }
- Error(sp, msg) => {
- sess.parse_sess
- .span_diagnostic
- .struct_span_err(sp.substitute_dummy(def.span), &msg)
- .emit();
- return dummy_syn_ext();
- }
- ErrorReported => {
- return dummy_syn_ext();
- }
- };
+ let argument_map =
+ match tt_parser.parse_tt(&mut Cow::Owned(parser), &argument_gram, &mut NoopTracker) {
+ Success(m) => m,
+ Failure(token, msg) => {
+ let s = parse_failure_msg(&token);
+ let sp = token.span.substitute_dummy(def.span);
+ let mut err = sess.parse_sess.span_diagnostic.struct_span_err(sp, &s);
+ err.span_label(sp, msg);
+ annotate_doc_comment(&mut err, sess.source_map(), sp);
+ err.emit();
+ return dummy_syn_ext();
+ }
+ Error(sp, msg) => {
+ sess.parse_sess
+ .span_diagnostic
+ .struct_span_err(sp.substitute_dummy(def.span), &msg)
+ .emit();
+ return dummy_syn_ext();
+ }
+ ErrorReported(_) => {
+ return dummy_syn_ext();
+ }
+ };
let mut valid = true;
projects / rust.git / blobdiff