print raw lifetime idents with `r#`

7 files changed, 166 insertions, 48 deletions

diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index fc816f2cb79..ea98bebd305 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -7,6 +7,7 @@ pub use NtPatKind::*;
 pub use TokenKind::*;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::edition::Edition;
+use rustc_span::symbol::IdentPrintMode;
 use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, kw, sym};
 #[allow(clippy::useless_attribute)] // FIXME: following use of `hidden_glob_reexports` incorrectly triggers `useless_attribute` lint.
 #[allow(hidden_glob_reexports)]
@@ -344,15 +345,24 @@ pub enum IdentIsRaw {
     Yes,
 }
 
-impl From<bool> for IdentIsRaw {
-    fn from(b: bool) -> Self {
-        if b { Self::Yes } else { Self::No }
+impl IdentIsRaw {
+    pub fn to_print_mode_ident(self) -> IdentPrintMode {
+        match self {
+            IdentIsRaw::No => IdentPrintMode::Normal,
+            IdentIsRaw::Yes => IdentPrintMode::RawIdent,
+        }
+    }
+    pub fn to_print_mode_lifetime(self) -> IdentPrintMode {
+        match self {
+            IdentIsRaw::No => IdentPrintMode::Normal,
+            IdentIsRaw::Yes => IdentPrintMode::RawLifetime,
+        }
     }
 }
 
-impl From<IdentIsRaw> for bool {
-    fn from(is_raw: IdentIsRaw) -> bool {
-        matches!(is_raw, IdentIsRaw::Yes)
+impl From<bool> for IdentIsRaw {
+    fn from(b: bool) -> Self {
+        if b { Self::Yes } else { Self::No }
     }
 }
 
diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs
index 85f76036df7..a056ce3e29d 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state.rs
@@ -10,7 +10,7 @@ use std::borrow::Cow;
 use std::sync::Arc;
 
 use rustc_ast::attr::AttrIdGenerator;
-use rustc_ast::token::{self, CommentKind, Delimiter, IdentIsRaw, Token, TokenKind};
+use rustc_ast::token::{self, CommentKind, Delimiter, Token, TokenKind};
 use rustc_ast::tokenstream::{Spacing, TokenStream, TokenTree};
 use rustc_ast::util::classify;
 use rustc_ast::util::comments::{Comment, CommentStyle};
@@ -441,7 +441,7 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
     fn print_generic_args(&mut self, args: &ast::GenericArgs, colons_before_params: bool);
 
     fn print_ident(&mut self, ident: Ident) {
-        self.word(IdentPrinter::for_ast_ident(ident, ident.is_raw_guess()).to_string());
+        self.word(IdentPrinter::for_ast_ident(ident, ident.guess_print_mode()).to_string());
         self.ann_post(ident)
     }
 
@@ -1015,17 +1015,16 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
 
             /* Name components */
             token::Ident(name, is_raw) => {
-                IdentPrinter::new(name, is_raw.into(), convert_dollar_crate).to_string().into()
+                IdentPrinter::new(name, is_raw.to_print_mode_ident(), convert_dollar_crate)
+                    .to_string()
+                    .into()
             }
             token::NtIdent(ident, is_raw) => {
-                IdentPrinter::for_ast_ident(ident, is_raw.into()).to_string().into()
+                IdentPrinter::for_ast_ident(ident, is_raw.to_print_mode_ident()).to_string().into()
             }
 
-            token::Lifetime(name, IdentIsRaw::No)
-            | token::NtLifetime(Ident { name, .. }, IdentIsRaw::No) => name.to_string().into(),
-            token::Lifetime(name, IdentIsRaw::Yes)
-            | token::NtLifetime(Ident { name, .. }, IdentIsRaw::Yes) => {
-                format!("'r#{}", &name.as_str()[1..]).into()
+            token::Lifetime(name, is_raw) | token::NtLifetime(Ident { name, .. }, is_raw) => {
+                IdentPrinter::new(name, is_raw.to_print_mode_lifetime(), None).to_string().into()
             }
 
             /* Other */
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index fd71f2ce948..5b1d3d6d35b 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -250,12 +250,14 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
                 Question => op("?"),
                 SingleQuote => op("'"),
 
-                Ident(sym, is_raw) => {
-                    trees.push(TokenTree::Ident(Ident { sym, is_raw: is_raw.into(), span }))
-                }
+                Ident(sym, is_raw) => trees.push(TokenTree::Ident(Ident {
+                    sym,
+                    is_raw: matches!(is_raw, IdentIsRaw::Yes),
+                    span,
+                })),
                 NtIdent(ident, is_raw) => trees.push(TokenTree::Ident(Ident {
                     sym: ident.name,
-                    is_raw: is_raw.into(),
+                    is_raw: matches!(is_raw, IdentIsRaw::Yes),
                     span: ident.span,
                 })),
 
@@ -263,7 +265,11 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
                     let ident = rustc_span::Ident::new(name, span).without_first_quote();
                     trees.extend([
                         TokenTree::Punct(Punct { ch: b'\'', joint: true, span }),
-                        TokenTree::Ident(Ident { sym: ident.name, is_raw: is_raw.into(), span }),
+                        TokenTree::Ident(Ident {
+                            sym: ident.name,
+                            is_raw: matches!(is_raw, IdentIsRaw::Yes),
+                            span,
+                        }),
                     ]);
                 }
                 NtLifetime(ident, is_raw) => {
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index 9b201e40d13..8ca77b0fa19 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -3094,7 +3094,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
         } else {
             self.suggest_introducing_lifetime(
                 &mut err,
-                Some(lifetime_ref.ident.name.as_str()),
+                Some(lifetime_ref.ident),
                 |err, _, span, message, suggestion, span_suggs| {
                     err.multipart_suggestion_verbose(
                         message,
@@ -3112,7 +3112,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
     fn suggest_introducing_lifetime(
         &self,
         err: &mut Diag<'_>,
-        name: Option<&str>,
+        name: Option<Ident>,
         suggest: impl Fn(
             &mut Diag<'_>,
             bool,
@@ -3159,7 +3159,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                     let mut rm_inner_binders: FxIndexSet<Span> = Default::default();
                     let (span, sugg) = if span.is_empty() {
                         let mut binder_idents: FxIndexSet<Ident> = Default::default();
-                        binder_idents.insert(Ident::from_str(name.unwrap_or("'a")));
+                        binder_idents.insert(name.unwrap_or(Ident::from_str("'a")));
 
                         // We need to special case binders in the following situation:
                         // Change `T: for<'a> Trait<T> + 'b` to `for<'a, 'b> T: Trait<T> + 'b`
@@ -3189,16 +3189,11 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                             }
                         }
 
-                        let binders_sugg = binder_idents.into_iter().enumerate().fold(
-                            "".to_string(),
-                            |mut binders, (i, x)| {
-                                if i != 0 {
-                                    binders += ", ";
-                                }
-                                binders += x.as_str();
-                                binders
-                            },
-                        );
+                        let binders_sugg: String = binder_idents
+                            .into_iter()
+                            .map(|ident| ident.to_string())
+                            .intersperse(", ".to_owned())
+                            .collect();
                         let sugg = format!(
                             "{}<{}>{}",
                             if higher_ranked { "for" } else { "" },
@@ -3214,7 +3209,8 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                             .source_map()
                             .span_through_char(span, '<')
                             .shrink_to_hi();
-                        let sugg = format!("{}, ", name.unwrap_or("'a"));
+                        let sugg =
+                            format!("{}, ", name.map(|i| i.to_string()).as_deref().unwrap_or("'a"));
                         (span, sugg)
                     };
 
@@ -3222,7 +3218,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                         let message = Cow::from(format!(
                             "consider making the {} lifetime-generic with a new `{}` lifetime",
                             kind.descr(),
-                            name.unwrap_or("'a"),
+                            name.map(|i| i.to_string()).as_deref().unwrap_or("'a"),
                         ));
                         should_continue = suggest(
                             err,
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index dcb1becc957..d6acd902c7c 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -2533,10 +2533,16 @@ impl fmt::Debug for Ident {
 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
 impl fmt::Display for Ident {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
+        fmt::Display::fmt(&IdentPrinter::new(self.name, self.guess_print_mode(), None), f)
     }
 }
 
+pub enum IdentPrintMode {
+    Normal,
+    RawIdent,
+    RawLifetime,
+}
+
 /// The most general type to print identifiers.
 ///
 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
@@ -2552,7 +2558,7 @@ impl fmt::Display for Ident {
 /// done for a token stream or a single token.
 pub struct IdentPrinter {
     symbol: Symbol,
-    is_raw: bool,
+    mode: IdentPrintMode,
     /// Span used for retrieving the crate name to which `$crate` refers to,
     /// if this field is `None` then the `$crate` conversion doesn't happen.
     convert_dollar_crate: Option<Span>,
@@ -2560,32 +2566,51 @@ pub struct IdentPrinter {
 
 impl IdentPrinter {
     /// The most general `IdentPrinter` constructor. Do not use this.
-    pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
-        IdentPrinter { symbol, is_raw, convert_dollar_crate }
+    pub fn new(
+        symbol: Symbol,
+        mode: IdentPrintMode,
+        convert_dollar_crate: Option<Span>,
+    ) -> IdentPrinter {
+        IdentPrinter { symbol, mode, convert_dollar_crate }
     }
 
     /// This implementation is supposed to be used when printing identifiers
     /// as a part of pretty-printing for larger AST pieces.
     /// Do not use this either.
-    pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
-        IdentPrinter::new(ident.name, is_raw, Some(ident.span))
+    pub fn for_ast_ident(ident: Ident, mode: IdentPrintMode) -> IdentPrinter {
+        IdentPrinter::new(ident.name, mode, Some(ident.span))
     }
 }
 
 impl fmt::Display for IdentPrinter {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if self.is_raw {
-            f.write_str("r#")?;
-        } else if self.symbol == kw::DollarCrate {
-            if let Some(span) = self.convert_dollar_crate {
+        let s = match self.mode {
+            IdentPrintMode::Normal
+                if self.symbol == kw::DollarCrate
+                    && let Some(span) = self.convert_dollar_crate =>
+            {
                 let converted = span.ctxt().dollar_crate_name();
                 if !converted.is_path_segment_keyword() {
                     f.write_str("::")?;
                 }
-                return fmt::Display::fmt(&converted, f);
+                converted
             }
-        }
-        fmt::Display::fmt(&self.symbol, f)
+            IdentPrintMode::Normal => self.symbol,
+            IdentPrintMode::RawIdent => {
+                f.write_str("r#")?;
+                self.symbol
+            }
+            IdentPrintMode::RawLifetime => {
+                f.write_str("'r#")?;
+                let s = self
+                    .symbol
+                    .as_str()
+                    .strip_prefix("'")
+                    .expect("only lifetime idents should be passed with RawLifetime mode");
+                Symbol::intern(s)
+            }
+        };
+        s.fmt(f)
     }
 }
 
@@ -3020,6 +3045,25 @@ impl Ident {
         self.name.can_be_raw() && self.is_reserved()
     }
 
+    pub fn is_raw_lifetime_guess(self) -> bool {
+        // this should be kept consistent with `Parser::expect_lifetime` found under
+        // compiler/rustc_parse/src/parser/ty.rs
+        let name_without_apostrophe = self.without_first_quote();
+        name_without_apostrophe.name != self.name
+            && ![kw::UnderscoreLifetime, kw::StaticLifetime].contains(&self.name)
+            && name_without_apostrophe.is_raw_guess()
+    }
+
+    pub fn guess_print_mode(self) -> IdentPrintMode {
+        if self.is_raw_lifetime_guess() {
+            IdentPrintMode::RawLifetime
+        } else if self.is_raw_guess() {
+            IdentPrintMode::RawIdent
+        } else {
+            IdentPrintMode::Normal
+        }
+    }
+
     /// Whether this would be the identifier for a tuple field like `self.0`, as
     /// opposed to a named field like `self.thing`.
     pub fn is_numeric(self) -> bool {
diff --git a/tests/ui/lifetimes/raw/use-of-undeclared-raw-lifetimes.rs b/tests/ui/lifetimes/raw/use-of-undeclared-raw-lifetimes.rs
new file mode 100644
index 00000000000..69461cfb200
--- /dev/null
+++ b/tests/ui/lifetimes/raw/use-of-undeclared-raw-lifetimes.rs
@@ -0,0 +1,21 @@
+// Check that we properly suggest `r#fn` if we use it undeclared.
+// https://github.com/rust-lang/rust/issues/143150
+//
+//@ edition: 2021
+
+fn a(_: dyn Trait + 'r#fn) {
+    //~^ ERROR use of undeclared lifetime name `'r#fn` [E0261]
+}
+
+trait Trait {}
+
+struct Test {
+    a: &'r#fn str,
+    //~^ ERROR use of undeclared lifetime name `'r#fn` [E0261]
+}
+
+trait Trait1<T>
+  where T: for<'a> Trait1<T> + 'r#fn { }
+//~^ ERROR use of undeclared lifetime name `'r#fn` [E0261]
+
+fn main() {}
diff --git a/tests/ui/lifetimes/raw/use-of-undeclared-raw-lifetimes.stderr b/tests/ui/lifetimes/raw/use-of-undeclared-raw-lifetimes.stderr
new file mode 100644
index 00000000000..8a17ce53dcf
--- /dev/null
+++ b/tests/ui/lifetimes/raw/use-of-undeclared-raw-lifetimes.stderr
@@ -0,0 +1,42 @@
+error[E0261]: use of undeclared lifetime name `'r#fn`
+  --> $DIR/use-of-undeclared-raw-lifetimes.rs:6:21
+   |
+LL | fn a(_: dyn Trait + 'r#fn) {
+   |                     ^^^^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'r#fn` here
+   |
+LL | fn a<'r#fn>(_: dyn Trait + 'r#fn) {
+   |     +++++++
+
+error[E0261]: use of undeclared lifetime name `'r#fn`
+  --> $DIR/use-of-undeclared-raw-lifetimes.rs:13:9
+   |
+LL |     a: &'r#fn str,
+   |         ^^^^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'r#fn` here
+   |
+LL | struct Test<'r#fn> {
+   |            +++++++
+
+error[E0261]: use of undeclared lifetime name `'r#fn`
+  --> $DIR/use-of-undeclared-raw-lifetimes.rs:18:32
+   |
+LL |   where T: for<'a> Trait1<T> + 'r#fn { }
+   |                                ^^^^^ undeclared lifetime
+   |
+   = note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
+help: consider making the bound lifetime-generic with a new `'r#fn` lifetime
+   |
+LL -   where T: for<'a> Trait1<T> + 'r#fn { }
+LL +   where for<'r#fn, 'a> T: Trait1<T> + 'r#fn { }
+   |
+help: consider introducing lifetime `'r#fn` here
+   |
+LL | trait Trait1<'r#fn, T>
+   |              ++++++
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0261`.