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

Before:

    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:

    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),
        },
    ]

3 files changed, 10 insertions, 5 deletions

diff --git a/src/libproc_macro/bridge/client.rs b/src/libproc_macro/bridge/client.rs
index d2222d12623..a8f6a90ef76 100644
--- a/src/libproc_macro/bridge/client.rs
+++ b/src/libproc_macro/bridge/client.rs
@@ -202,10 +202,15 @@ 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")
+            .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 31bc61263ab..f34a39996fe 100644
--- a/src/libproc_macro/lib.rs
+++ b/src/libproc_macro/lib.rs
@@ -1134,7 +1134,6 @@ 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)
     }
 }