Make rustc_parse_format compile on stable

This allows it to be used by lightweight formatting systems and may
allow it to be used by rust-analyzer.

Cargo.lock

@@ -4171,7 +4171,6 @@ name = "rustc_parse_format"
 version = "0.0.0"
 dependencies = [
  "rustc_lexer",
- "rustc_span",
 ]
 
 [[package]]

compiler/rustc_builtin_macros/src/asm.rs

@@ -626,15 +626,15 @@ fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::Inl
 
         if !parser.errors.is_empty() {
             let err = parser.errors.remove(0);
-            let err_sp = template_span.from_inner(err.span);
+            let err_sp = template_span.from_inner(InnerSpan::new(err.span.start, err.span.end));
             let msg = &format!("invalid asm template string: {}", err.description);
             let mut e = ecx.struct_span_err(err_sp, msg);
             e.span_label(err_sp, err.label + " in asm template string");
             if let Some(note) = err.note {
                 e.note(&note);
             }
             if let Some((label, span)) = err.secondary_label {
-                let err_sp = template_span.from_inner(span);
+                let err_sp = template_span.from_inner(InnerSpan::new(span.start, span.end));
                 e.span_label(err_sp, label);
             }
             e.emit();
@@ -643,7 +643,10 @@ fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::Inl
 
         curarg = parser.curarg;
 
-        let mut arg_spans = parser.arg_places.iter().map(|span| template_span.from_inner(*span));
+        let mut arg_spans = parser
+            .arg_places
+            .iter()
+            .map(|span| template_span.from_inner(InnerSpan::new(span.start, span.end)));
         for piece in unverified_pieces {
             match piece {
                 parse::Piece::String(s) => {
@@ -699,14 +702,21 @@ fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::Inl
                                 Some(idx)
                             }
                         }
-                        parse::ArgumentNamed(name, span) => match args.named_args.get(&name) {
-                            Some(&idx) => Some(idx),
-                            None => {
-                                let msg = format!("there is no argument named `{}`", name);
-                                ecx.struct_span_err(template_span.from_inner(span), &msg).emit();
-                                None
+                        parse::ArgumentNamed(name, span) => {
+                            match args.named_args.get(&Symbol::intern(name)) {
+                                Some(&idx) => Some(idx),
+                                None => {
+                                    let msg = format!("there is no argument named `{}`", name);
+                                    ecx.struct_span_err(
+                                        template_span
+                                            .from_inner(InnerSpan::new(span.start, span.end)),
+                                        &msg,
+                                    )
+                                    .emit();
+                                    None
+                                }
                             }
-                        },
+                        }
                     };
 
                     let mut chars = arg.format.ty.chars();
@@ -715,7 +725,7 @@ fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::Inl
                         let span = arg
                             .format
                             .ty_span
-                            .map(|sp| template_sp.from_inner(sp))
+                            .map(|sp| template_sp.from_inner(InnerSpan::new(sp.start, sp.end)))
                             .unwrap_or(template_sp);
                         ecx.struct_span_err(
                             span,
@@ -741,7 +751,12 @@ fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::Inl
             let template_num_lines = 1 + template_str.matches('\n').count();
             line_spans.extend(std::iter::repeat(template_sp).take(template_num_lines));
         } else {
-            line_spans.extend(parser.line_spans.iter().map(|span| template_span.from_inner(*span)));
+            line_spans.extend(
+                parser
+                    .line_spans
+                    .iter()
+                    .map(|span| template_span.from_inner(InnerSpan::new(span.start, span.end))),
+            );
         };
     }
 

compiler/rustc_builtin_macros/src/format.rs

@@ -242,7 +242,7 @@ impl<'a, 'b> Context<'a, 'b> {
     fn resolve_name_inplace(&self, p: &mut parse::Piece<'_>) {
         // NOTE: the `unwrap_or` branch is needed in case of invalid format
         // arguments, e.g., `format_args!("{foo}")`.
-        let lookup = |s: Symbol| *self.names.get(&s).unwrap_or(&0);
+        let lookup = |s: &str| *self.names.get(&Symbol::intern(s)).unwrap_or(&0);
 
         match *p {
             parse::String(_) => {}
@@ -276,7 +276,9 @@ impl<'a, 'b> Context<'a, 'b> {
                 // it's written second, so it should come after width/precision.
                 let pos = match arg.position {
                     parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => Exact(i),
-                    parse::ArgumentNamed(s, span) => Named(s, span),
+                    parse::ArgumentNamed(s, span) => {
+                        Named(Symbol::intern(s), InnerSpan::new(span.start, span.end))
+                    }
                 };
 
                 let ty = Placeholder(match arg.format.ty {
@@ -291,7 +293,10 @@ impl<'a, 'b> Context<'a, 'b> {
                     "X" => "UpperHex",
                     _ => {
                         let fmtsp = self.fmtsp;
-                        let sp = arg.format.ty_span.map(|sp| fmtsp.from_inner(sp));
+                        let sp = arg
+                            .format
+                            .ty_span
+                            .map(|sp| fmtsp.from_inner(InnerSpan::new(sp.start, sp.end)));
                         let mut err = self.ecx.struct_span_err(
                             sp.unwrap_or(fmtsp),
                             &format!("unknown format trait `{}`", arg.format.ty),
@@ -340,14 +345,17 @@ impl<'a, 'b> Context<'a, 'b> {
         }
     }
 
-    fn verify_count(&mut self, c: parse::Count) {
+    fn verify_count(&mut self, c: parse::Count<'_>) {
         match c {
             parse::CountImplied | parse::CountIs(..) => {}
             parse::CountIsParam(i) => {
                 self.verify_arg_type(Exact(i), Count);
             }
             parse::CountIsName(s, span) => {
-                self.verify_arg_type(Named(s, span), Count);
+                self.verify_arg_type(
+                    Named(Symbol::intern(s), InnerSpan::new(span.start, span.end)),
+                    Count,
+                );
             }
         }
     }
@@ -425,7 +433,7 @@ impl<'a, 'b> Context<'a, 'b> {
 
         for fmt in &self.arg_with_formatting {
             if let Some(span) = fmt.precision_span {
-                let span = self.fmtsp.from_inner(span);
+                let span = self.fmtsp.from_inner(InnerSpan::new(span.start, span.end));
                 match fmt.precision {
                     parse::CountIsParam(pos) if pos > self.num_args() => {
                         e.span_label(
@@ -471,7 +479,7 @@ impl<'a, 'b> Context<'a, 'b> {
                 }
             }
             if let Some(span) = fmt.width_span {
-                let span = self.fmtsp.from_inner(span);
+                let span = self.fmtsp.from_inner(InnerSpan::new(span.start, span.end));
                 match fmt.width {
                     parse::CountIsParam(pos) if pos > self.num_args() => {
                         e.span_label(
@@ -610,7 +618,7 @@ impl<'a, 'b> Context<'a, 'b> {
         ecx.std_path(&[sym::fmt, sym::rt, sym::v1, s])
     }
 
-    fn build_count(&self, c: parse::Count) -> P<ast::Expr> {
+    fn build_count(&self, c: parse::Count<'_>) -> P<ast::Expr> {
         let sp = self.macsp;
         let count = |c, arg| {
             let mut path = Context::rtpath(self.ecx, sym::Count);
@@ -1033,7 +1041,7 @@ pub fn expand_preparsed_format_args(
     if !parser.errors.is_empty() {
         let err = parser.errors.remove(0);
         let sp = if efmt_kind_is_lit {
-            fmt_span.from_inner(err.span)
+            fmt_span.from_inner(InnerSpan::new(err.span.start, err.span.end))
         } else {
             // The format string could be another macro invocation, e.g.:
             //     format!(concat!("abc", "{}"), 4);
@@ -1052,14 +1060,18 @@ pub fn expand_preparsed_format_args(
         }
         if let Some((label, span)) = err.secondary_label {
             if efmt_kind_is_lit {
-                e.span_label(fmt_span.from_inner(span), label);
+                e.span_label(fmt_span.from_inner(InnerSpan::new(span.start, span.end)), label);
             }
         }
         e.emit();
         return DummyResult::raw_expr(sp, true);
     }
 
-    let arg_spans = parser.arg_places.iter().map(|span| fmt_span.from_inner(*span)).collect();
+    let arg_spans = parser
+        .arg_places
+        .iter()
+        .map(|span| fmt_span.from_inner(InnerSpan::new(span.start, span.end)))
+        .collect();
 
     let named_pos: FxHashSet<usize> = names.values().cloned().collect();
 

compiler/rustc_lint/src/non_fmt_panic.rs

@@ -254,7 +254,10 @@ fn check_panic_str<'tcx>(
     if n_arguments > 0 && fmt_parser.errors.is_empty() {
         let arg_spans: Vec<_> = match &fmt_parser.arg_places[..] {
             [] => vec![fmt_span],
-            v => v.iter().map(|span| fmt_span.from_inner(*span)).collect(),
+            v => v
+                .iter()
+                .map(|span| fmt_span.from_inner(InnerSpan::new(span.start, span.end)))
+                .collect(),
         };
         cx.struct_span_lint(NON_FMT_PANICS, arg_spans, |lint| {
             let mut l = lint.build(match n_arguments {

compiler/rustc_parse_format/Cargo.toml

@@ -4,5 +4,4 @@ version = "0.0.0"
 edition = "2021"
 
 [dependencies]
-rustc_span = { path = "../rustc_span" }
 rustc_lexer = { path = "../rustc_lexer" }

compiler/rustc_parse_format/src/lib.rs

@@ -9,8 +9,8 @@
     html_playground_url = "https://play.rust-lang.org/",
     test(attr(deny(warnings)))
 )]
-#![feature(nll)]
-#![feature(bool_to_option)]
+// We want to be able to build this crate with a stable compiler, so no
+// `#![feature]` attributes should be added.
 
 pub use Alignment::*;
 pub use Count::*;
@@ -22,7 +22,19 @@ use std::iter;
 use std::str;
 use std::string;
 
-use rustc_span::{InnerSpan, Symbol};
+// Note: copied from rustc_span
+/// Range inside of a `Span` used for diagnostics when we only have access to relative positions.
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub struct InnerSpan {
+    pub start: usize,
+    pub end: usize,
+}
+
+impl InnerSpan {
+    pub fn new(start: usize, end: usize) -> InnerSpan {
+        InnerSpan { start, end }
+    }
+}
 
 /// The type of format string that we are parsing.
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
@@ -57,7 +69,7 @@ pub enum Piece<'a> {
 #[derive(Copy, Clone, Debug, PartialEq)]
 pub struct Argument<'a> {
     /// Where to find this argument
-    pub position: Position,
+    pub position: Position<'a>,
     /// How to format the argument
     pub format: FormatSpec<'a>,
 }
@@ -72,11 +84,11 @@ pub struct FormatSpec<'a> {
     /// Packed version of various flags provided.
     pub flags: u32,
     /// The integer precision to use.
-    pub precision: Count,
+    pub precision: Count<'a>,
     /// The span of the precision formatting flag (for diagnostics).
     pub precision_span: Option<InnerSpan>,
     /// The string width requested for the resulting format.
-    pub width: Count,
+    pub width: Count<'a>,
     /// The span of the width formatting flag (for diagnostics).
     pub width_span: Option<InnerSpan>,
     /// The descriptor string representing the name of the format desired for
@@ -89,16 +101,16 @@ pub struct FormatSpec<'a> {
 
 /// Enum describing where an argument for a format can be located.
 #[derive(Copy, Clone, Debug, PartialEq)]
-pub enum Position {
+pub enum Position<'a> {
     /// The argument is implied to be located at an index
     ArgumentImplicitlyIs(usize),
     /// The argument is located at a specific index given in the format
     ArgumentIs(usize),
     /// The argument has a name.
-    ArgumentNamed(Symbol, InnerSpan),
+    ArgumentNamed(&'a str, InnerSpan),
 }
 
-impl Position {
+impl Position<'_> {
     pub fn index(&self) -> Option<usize> {
         match self {
             ArgumentIs(i) | ArgumentImplicitlyIs(i) => Some(*i),
@@ -143,11 +155,11 @@ pub enum Flag {
 /// A count is used for the precision and width parameters of an integer, and
 /// can reference either an argument or a literal integer.
 #[derive(Copy, Clone, Debug, PartialEq)]
-pub enum Count {
+pub enum Count<'a> {
     /// The count is specified explicitly.
     CountIs(usize),
     /// The count is specified by the argument with the given name.
-    CountIsName(Symbol, InnerSpan),
+    CountIsName(&'a str, InnerSpan),
     /// The count is specified by the argument at the given index.
     CountIsParam(usize),
     /// The count is implied and cannot be explicitly specified.
@@ -489,7 +501,7 @@ impl<'a> Parser<'a> {
     /// integer index of an argument, a named argument, or a blank string.
     /// Returns `Some(parsed_position)` if the position is not implicitly
     /// consuming a macro argument, `None` if it's the case.
-    fn position(&mut self) -> Option<Position> {
+    fn position(&mut self) -> Option<Position<'a>> {
         if let Some(i) = self.integer() {
             Some(ArgumentIs(i))
         } else {
@@ -498,7 +510,7 @@ impl<'a> Parser<'a> {
                     let word = self.word();
                     let end = start + word.len();
                     let span = self.to_span_index(start).to(self.to_span_index(end));
-                    Some(ArgumentNamed(Symbol::intern(word), span))
+                    Some(ArgumentNamed(word, span))
                 }
 
                 // This is an `ArgumentNext`.
@@ -651,7 +663,7 @@ impl<'a> Parser<'a> {
     /// Parses a `Count` parameter at the current position. This does not check
     /// for 'CountIsNextParam' because that is only used in precision, not
     /// width.
-    fn count(&mut self, start: usize) -> (Count, Option<InnerSpan>) {
+    fn count(&mut self, start: usize) -> (Count<'a>, Option<InnerSpan>) {
         if let Some(i) = self.integer() {
             if let Some(end) = self.consume_pos('$') {
                 let span = self.to_span_index(start).to(self.to_span_index(end + 1));
@@ -667,7 +679,7 @@ impl<'a> Parser<'a> {
                 (CountImplied, None)
             } else if let Some(end) = self.consume_pos('$') {
                 let span = self.to_span_index(start + 1).to(self.to_span_index(end));
-                (CountIsName(Symbol::intern(word), span), None)
+                (CountIsName(word, span), None)
             } else {
                 self.cur = tmp;
                 (CountImplied, None)
@@ -723,7 +735,7 @@ impl<'a> Parser<'a> {
                 break;
             }
         }
-        found.then_some(cur)
+        if found { Some(cur) } else { None }
     }
 }