Rollup merge of #72233 - dtolnay:literal, r=petrochenkov

Fix {:#?} representation of proc_macro::Literal

Before:

```rust
TokenStream [
    Ident {
        ident: "name",
        span: #0 bytes(37..41),
    },
    Punct {
        ch: '=',
        spacing: Alone,
        span: #0 bytes(42..43),
    },
    Literal { lit: Lit { kind: Str, symbol: "SNPP", suffix: None }, span: Span { lo: BytePos(44), hi: BytePos(50), ctxt: #0 } },
    Punct {
        ch: ',',
        spacing: Alone,
        span: #0 bytes(50..51),
    },
    Ident {
        ident: "owner",
        span: #0 bytes(56..61),
    },
    Punct {
        ch: '=',
        spacing: Alone,
        span: #0 bytes(62..63),
    },
    Literal { lit: Lit { kind: Str, symbol: "Canary M Burns", suffix: None }, span: Span { lo: BytePos(64), hi: BytePos(80), ctxt: #0 } },
]
```

After:

```rust
TokenStream [
    Ident {
        ident: "name",
        span: #0 bytes(37..41),
    },
    Punct {
        ch: '=',
        spacing: Alone,
        span: #0 bytes(42..43),
    },
    Literal {
        kind: Str,
        symbol: "SNPP",
        suffix: None,
        span: #0 bytes(44..50),
    },
    Punct {
        ch: ',',
        spacing: Alone,
        span: #0 bytes(50..51),
    },
    Ident {
        ident: "owner",
        span: #0 bytes(56..61),
    },
    Punct {
        ch: '=',
        spacing: Alone,
        span: #0 bytes(62..63),
    },
    Literal {
        kind: Str,
        symbol: "Canary M Burns",
        suffix: None,
        span: #0 bytes(64..80),
    },
]
```

8 files changed, 241 insertions, 9 deletions

diff --git a/src/libproc_macro/bridge/client.rs b/src/libproc_macro/bridge/client.rs
index d2222d12623..283aa25b0ea 100644
--- a/src/libproc_macro/bridge/client.rs
+++ b/src/libproc_macro/bridge/client.rs
@@ -202,10 +202,16 @@ impl Clone for Literal {
     }
 }
 
-// FIXME(eddyb) `Literal` should not expose internal `Debug` impls.
 impl fmt::Debug for Literal {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(&self.debug())
+        f.debug_struct("Literal")
+            // format the kind without quotes, as in `kind: Float`
+            .field("kind", &format_args!("{}", &self.debug_kind()))
+            .field("symbol", &self.symbol())
+            // format `Some("...")` on one line even in {:#?} mode
+            .field("suffix", &format_args!("{:?}", &self.suffix()))
+            .field("span", &self.span())
+            .finish()
     }
 }
 
diff --git a/src/libproc_macro/bridge/mod.rs b/src/libproc_macro/bridge/mod.rs
index a0e7d90f497..bf0d8fcee5b 100644
--- a/src/libproc_macro/bridge/mod.rs
+++ b/src/libproc_macro/bridge/mod.rs
@@ -103,8 +103,9 @@ macro_rules! with_api {
             Literal {
                 fn drop($self: $S::Literal);
                 fn clone($self: &$S::Literal) -> $S::Literal;
-                // FIXME(eddyb) `Literal` should not expose internal `Debug` impls.
-                fn debug($self: &$S::Literal) -> String;
+                fn debug_kind($self: &$S::Literal) -> String;
+                fn symbol($self: &$S::Literal) -> String;
+                fn suffix($self: &$S::Literal) -> Option<String>;
                 fn integer(n: &str) -> $S::Literal;
                 fn typed_integer(n: &str, kind: &str) -> $S::Literal;
                 fn float(n: &str) -> $S::Literal;
diff --git a/src/libproc_macro/lib.rs b/src/libproc_macro/lib.rs
index b6544341fa9..f11401b5a0c 100644
--- a/src/libproc_macro/lib.rs
+++ b/src/libproc_macro/lib.rs
@@ -1141,7 +1141,6 @@ impl fmt::Display for Literal {
 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
 impl fmt::Debug for Literal {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        // FIXME(eddyb) `Literal` should not expose internal `Debug` impls.
         self.0.fmt(f)
     }
 }
diff --git a/src/librustc_expand/proc_macro_server.rs b/src/librustc_expand/proc_macro_server.rs
index afc6dc36eb4..b9693c2c862 100644
--- a/src/librustc_expand/proc_macro_server.rs
+++ b/src/librustc_expand/proc_macro_server.rs
@@ -507,9 +507,14 @@ impl server::Ident for Rustc<'_> {
 }
 
 impl server::Literal for Rustc<'_> {
-    // FIXME(eddyb) `Literal` should not expose internal `Debug` impls.
-    fn debug(&mut self, literal: &Self::Literal) -> String {
-        format!("{:?}", literal)
+    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)
diff --git a/src/test/ui/lint/redundant-semicolon/redundant-semi-proc-macro.stderr b/src/test/ui/lint/redundant-semicolon/redundant-semi-proc-macro.stderr
index a79fba9bf3f..bc0c5330324 100644
--- a/src/test/ui/lint/redundant-semicolon/redundant-semi-proc-macro.stderr
+++ b/src/test/ui/lint/redundant-semicolon/redundant-semi-proc-macro.stderr
@@ -1,4 +1,4 @@
-TokenStream [Ident { ident: "fn", span: #0 bytes(198..200) }, Ident { ident: "span_preservation", span: #0 bytes(201..218) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(218..220) }, Group { delimiter: Brace, stream: TokenStream [Ident { ident: "let", span: #0 bytes(228..231) }, Ident { ident: "tst", span: #0 bytes(232..235) }, Punct { ch: '=', spacing: Alone, span: #0 bytes(236..237) }, Literal { lit: Lit { kind: Integer, symbol: "123", suffix: None }, span: Span { lo: BytePos(238), hi: BytePos(241), ctxt: #0 } }, Punct { ch: ';', spacing: Joint, span: #0 bytes(241..242) }, Punct { ch: ';', spacing: Alone, span: #0 bytes(242..243) }, Ident { ident: "match", span: #0 bytes(289..294) }, Ident { ident: "tst", span: #0 bytes(295..298) }, Group { delimiter: Brace, stream: TokenStream [Literal { lit: Lit { kind: Integer, symbol: "123", suffix: None }, span: Span { lo: BytePos(483), hi: BytePos(486), ctxt: #0 } }, Punct { ch: '=', spacing: Joint, span: #0 bytes(487..489) }, Punct { ch: '>', spacing: Alone, span: #0 bytes(487..489) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(490..492) }, Punct { ch: ',', spacing: Alone, span: #0 bytes(492..493) }, Ident { ident: "_", span: #0 bytes(502..503) }, Punct { ch: '=', spacing: Joint, span: #0 bytes(504..506) }, Punct { ch: '>', spacing: Alone, span: #0 bytes(504..506) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(507..509) }], span: #0 bytes(299..515) }, Punct { ch: ';', spacing: Joint, span: #0 bytes(515..516) }, Punct { ch: ';', spacing: Joint, span: #0 bytes(516..517) }, Punct { ch: ';', spacing: Alone, span: #0 bytes(517..518) }], span: #0 bytes(222..562) }]
+TokenStream [Ident { ident: "fn", span: #0 bytes(198..200) }, Ident { ident: "span_preservation", span: #0 bytes(201..218) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(218..220) }, Group { delimiter: Brace, stream: TokenStream [Ident { ident: "let", span: #0 bytes(228..231) }, Ident { ident: "tst", span: #0 bytes(232..235) }, Punct { ch: '=', spacing: Alone, span: #0 bytes(236..237) }, Literal { kind: Integer, symbol: "123", suffix: None, span: #0 bytes(238..241) }, Punct { ch: ';', spacing: Joint, span: #0 bytes(241..242) }, Punct { ch: ';', spacing: Alone, span: #0 bytes(242..243) }, Ident { ident: "match", span: #0 bytes(289..294) }, Ident { ident: "tst", span: #0 bytes(295..298) }, Group { delimiter: Brace, stream: TokenStream [Literal { kind: Integer, symbol: "123", suffix: None, span: #0 bytes(483..486) }, Punct { ch: '=', spacing: Joint, span: #0 bytes(487..489) }, Punct { ch: '>', spacing: Alone, span: #0 bytes(487..489) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(490..492) }, Punct { ch: ',', spacing: Alone, span: #0 bytes(492..493) }, Ident { ident: "_", span: #0 bytes(502..503) }, Punct { ch: '=', spacing: Joint, span: #0 bytes(504..506) }, Punct { ch: '>', spacing: Alone, span: #0 bytes(504..506) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(507..509) }], span: #0 bytes(299..515) }, Punct { ch: ';', spacing: Joint, span: #0 bytes(515..516) }, Punct { ch: ';', spacing: Joint, span: #0 bytes(516..517) }, Punct { ch: ';', spacing: Alone, span: #0 bytes(517..518) }], span: #0 bytes(222..562) }]
 error: unnecessary trailing semicolon
   --> $DIR/redundant-semi-proc-macro.rs:9:19
    |
diff --git a/src/test/ui/proc-macro/debug/auxiliary/macro-dump-debug.rs b/src/test/ui/proc-macro/debug/auxiliary/macro-dump-debug.rs
new file mode 100644
index 00000000000..56ad0612f74
--- /dev/null
+++ b/src/test/ui/proc-macro/debug/auxiliary/macro-dump-debug.rs
@@ -0,0 +1,15 @@
+// force-host
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+#![crate_name = "macro_dump_debug"]
+
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro]
+pub fn dump_debug(tokens: TokenStream) -> TokenStream {
+    eprintln!("{:?}", tokens);
+    eprintln!("{:#?}", tokens);
+    TokenStream::new()
+}
diff --git a/src/test/ui/proc-macro/debug/dump-debug.rs b/src/test/ui/proc-macro/debug/dump-debug.rs
new file mode 100644
index 00000000000..0ed36b690f4
--- /dev/null
+++ b/src/test/ui/proc-macro/debug/dump-debug.rs
@@ -0,0 +1,40 @@
+// run-pass
+// aux-build:macro-dump-debug.rs
+
+extern crate macro_dump_debug;
+use macro_dump_debug::dump_debug;
+
+dump_debug! {
+    ident   // ident
+    r#ident // raw ident
+    ,       // alone punct
+    ==>     // joint punct
+    ()      // empty group
+    [_]     // nonempty group
+
+    // unsuffixed literals
+    0
+    1.0
+    "S"
+    b"B"
+    r"R"
+    r##"R"##
+    br"BR"
+    br##"BR"##
+    'C'
+    b'B'
+
+    // suffixed literals
+    0q
+    1.0q
+    "S"q
+    b"B"q
+    r"R"q
+    r##"R"##q
+    br"BR"q
+    br##"BR"##q
+    'C'q
+    b'B'q
+}
+
+fn main() {}
diff --git a/src/test/ui/proc-macro/debug/dump-debug.stderr b/src/test/ui/proc-macro/debug/dump-debug.stderr
new file mode 100644
index 00000000000..0aedefd4e60
--- /dev/null
+++ b/src/test/ui/proc-macro/debug/dump-debug.stderr
@@ -0,0 +1,166 @@
+TokenStream [Ident { ident: "ident", span: #0 bytes(130..135) }, Ident { ident: "r#ident", span: #0 bytes(151..158) }, Punct { ch: ',', spacing: Alone, span: #0 bytes(176..177) }, Punct { ch: '=', spacing: Joint, span: #0 bytes(203..205) }, Punct { ch: '=', spacing: Joint, span: #0 bytes(203..205) }, Punct { ch: '>', spacing: Alone, span: #0 bytes(205..206) }, Group { delimiter: Parenthesis, stream: TokenStream [], span: #0 bytes(230..232) }, Group { delimiter: Bracket, stream: TokenStream [Ident { ident: "_", span: #0 bytes(258..259) }], span: #0 bytes(257..260) }, Literal { kind: Integer, symbol: "0", suffix: None, span: #0 bytes(315..316) }, Literal { kind: Float, symbol: "1.0", suffix: None, span: #0 bytes(321..324) }, Literal { kind: Str, symbol: "S", suffix: None, span: #0 bytes(329..332) }, Literal { kind: ByteStr, symbol: "B", suffix: None, span: #0 bytes(337..341) }, Literal { kind: StrRaw(0), symbol: "R", suffix: None, span: #0 bytes(346..350) }, Literal { kind: StrRaw(2), symbol: "R", suffix: None, span: #0 bytes(355..363) }, Literal { kind: ByteStrRaw(0), symbol: "BR", suffix: None, span: #0 bytes(368..374) }, Literal { kind: ByteStrRaw(2), symbol: "BR", suffix: None, span: #0 bytes(379..389) }, Literal { kind: Char, symbol: "C", suffix: None, span: #0 bytes(394..397) }, Literal { kind: Byte, symbol: "B", suffix: None, span: #0 bytes(402..406) }, Literal { kind: Integer, symbol: "0", suffix: Some("q"), span: #0 bytes(437..439) }, Literal { kind: Float, symbol: "1.0", suffix: Some("q"), span: #0 bytes(444..448) }, Literal { kind: Str, symbol: "S", suffix: Some("q"), span: #0 bytes(453..457) }, Literal { kind: ByteStr, symbol: "B", suffix: Some("q"), span: #0 bytes(462..467) }, Literal { kind: StrRaw(0), symbol: "R", suffix: Some("q"), span: #0 bytes(472..477) }, Literal { kind: StrRaw(2), symbol: "R", suffix: Some("q"), span: #0 bytes(482..491) }, Literal { kind: ByteStrRaw(0), symbol: "BR", suffix: Some("q"), span: #0 bytes(496..503) }, Literal { kind: ByteStrRaw(2), symbol: "BR", suffix: Some("q"), span: #0 bytes(508..519) }, Literal { kind: Char, symbol: "C", suffix: Some("q"), span: #0 bytes(524..528) }, Literal { kind: Byte, symbol: "B", suffix: Some("q"), span: #0 bytes(533..538) }]
+TokenStream [
+    Ident {
+        ident: "ident",
+        span: #0 bytes(130..135),
+    },
+    Ident {
+        ident: "r#ident",
+        span: #0 bytes(151..158),
+    },
+    Punct {
+        ch: ',',
+        spacing: Alone,
+        span: #0 bytes(176..177),
+    },
+    Punct {
+        ch: '=',
+        spacing: Joint,
+        span: #0 bytes(203..205),
+    },
+    Punct {
+        ch: '=',
+        spacing: Joint,
+        span: #0 bytes(203..205),
+    },
+    Punct {
+        ch: '>',
+        spacing: Alone,
+        span: #0 bytes(205..206),
+    },
+    Group {
+        delimiter: Parenthesis,
+        stream: TokenStream [],
+        span: #0 bytes(230..232),
+    },
+    Group {
+        delimiter: Bracket,
+        stream: TokenStream [
+            Ident {
+                ident: "_",
+                span: #0 bytes(258..259),
+            },
+        ],
+        span: #0 bytes(257..260),
+    },
+    Literal {
+        kind: Integer,
+        symbol: "0",
+        suffix: None,
+        span: #0 bytes(315..316),
+    },
+    Literal {
+        kind: Float,
+        symbol: "1.0",
+        suffix: None,
+        span: #0 bytes(321..324),
+    },
+    Literal {
+        kind: Str,
+        symbol: "S",
+        suffix: None,
+        span: #0 bytes(329..332),
+    },
+    Literal {
+        kind: ByteStr,
+        symbol: "B",
+        suffix: None,
+        span: #0 bytes(337..341),
+    },
+    Literal {
+        kind: StrRaw(0),
+        symbol: "R",
+        suffix: None,
+        span: #0 bytes(346..350),
+    },
+    Literal {
+        kind: StrRaw(2),
+        symbol: "R",
+        suffix: None,
+        span: #0 bytes(355..363),
+    },
+    Literal {
+        kind: ByteStrRaw(0),
+        symbol: "BR",
+        suffix: None,
+        span: #0 bytes(368..374),
+    },
+    Literal {
+        kind: ByteStrRaw(2),
+        symbol: "BR",
+        suffix: None,
+        span: #0 bytes(379..389),
+    },
+    Literal {
+        kind: Char,
+        symbol: "C",
+        suffix: None,
+        span: #0 bytes(394..397),
+    },
+    Literal {
+        kind: Byte,
+        symbol: "B",
+        suffix: None,
+        span: #0 bytes(402..406),
+    },
+    Literal {
+        kind: Integer,
+        symbol: "0",
+        suffix: Some("q"),
+        span: #0 bytes(437..439),
+    },
+    Literal {
+        kind: Float,
+        symbol: "1.0",
+        suffix: Some("q"),
+        span: #0 bytes(444..448),
+    },
+    Literal {
+        kind: Str,
+        symbol: "S",
+        suffix: Some("q"),
+        span: #0 bytes(453..457),
+    },
+    Literal {
+        kind: ByteStr,
+        symbol: "B",
+        suffix: Some("q"),
+        span: #0 bytes(462..467),
+    },
+    Literal {
+        kind: StrRaw(0),
+        symbol: "R",
+        suffix: Some("q"),
+        span: #0 bytes(472..477),
+    },
+    Literal {
+        kind: StrRaw(2),
+        symbol: "R",
+        suffix: Some("q"),
+        span: #0 bytes(482..491),
+    },
+    Literal {
+        kind: ByteStrRaw(0),
+        symbol: "BR",
+        suffix: Some("q"),
+        span: #0 bytes(496..503),
+    },
+    Literal {
+        kind: ByteStrRaw(2),
+        symbol: "BR",
+        suffix: Some("q"),
+        span: #0 bytes(508..519),
+    },
+    Literal {
+        kind: Char,
+        symbol: "C",
+        suffix: Some("q"),
+        span: #0 bytes(524..528),
+    },
+    Literal {
+        kind: Byte,
+        symbol: "B",
+        suffix: Some("q"),
+        span: #0 bytes(533..538),
+    },
+]