Rollup merge of #65363 - Centril:less-pprust, r=Mark-Simulacrum

Remove implicit dependencies on syntax::pprust

Part of https://github.com/rust-lang/rust/pull/65324.

The main goal here is to facilitate the eventual move of pprust out from libsyntax and because an AST definition typically should not depend on its pretty printer.

r? @estebank

9 files changed, 57 insertions, 77 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 023952042e6..79d91125ec4 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -7,7 +7,6 @@ pub use crate::util::parser::ExprPrecedence;
 
 use crate::ext::hygiene::ExpnId;
 use crate::parse::token::{self, DelimToken};
-use crate::print::pprust;
 use crate::ptr::P;
 use crate::source_map::{dummy_spanned, respan, Spanned};
 use crate::symbol::{kw, sym, Symbol};
@@ -70,7 +69,7 @@ impl fmt::Display for Lifetime {
 /// along with a bunch of supporting information.
 ///
 /// E.g., `std::cmp::PartialEq`.
-#[derive(Clone, RustcEncodable, RustcDecodable)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Path {
     pub span: Span,
     /// The segments in the path: the things separated by `::`.
@@ -86,18 +85,6 @@ impl PartialEq<Symbol> for Path {
     }
 }
 
-impl fmt::Debug for Path {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "path({})", pprust::path_to_string(self))
-    }
-}
-
-impl fmt::Display for Path {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}", pprust::path_to_string(self))
-    }
-}
-
 impl Path {
     // Convert a span and an identifier to the corresponding
     // one-segment path.
@@ -507,19 +494,13 @@ pub struct Block {
     pub span: Span,
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Pat {
     pub id: NodeId,
     pub kind: PatKind,
     pub span: Span,
 }
 
-impl fmt::Debug for Pat {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "pat({}: {})", self.id, pprust::pat_to_string(self))
-    }
-}
-
 impl Pat {
     /// Attempt reparsing the pattern as a type.
     /// This is intended for use by diagnostics.
@@ -831,7 +812,7 @@ impl UnOp {
 }
 
 /// A statement
-#[derive(Clone, RustcEncodable, RustcDecodable)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Stmt {
     pub id: NodeId,
     pub kind: StmtKind,
@@ -865,18 +846,7 @@ impl Stmt {
     }
 }
 
-impl fmt::Debug for Stmt {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "stmt({}: {})",
-            self.id.to_string(),
-            pprust::stmt_to_string(self)
-        )
-    }
-}
-
-#[derive(Clone, RustcEncodable, RustcDecodable)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub enum StmtKind {
     /// A local (let) binding.
     Local(P<Local>),
@@ -973,7 +943,7 @@ pub struct AnonConst {
 }
 
 /// An expression.
-#[derive(Clone, RustcEncodable, RustcDecodable)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Expr {
     pub id: NodeId,
     pub kind: ExprKind,
@@ -1100,12 +1070,6 @@ impl Expr {
     }
 }
 
-impl fmt::Debug for Expr {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "expr({}: {})", self.id, pprust::expr_to_string(self))
-    }
-}
-
 /// Limit types of a range (inclusive or exclusive)
 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug)]
 pub enum RangeLimits {
@@ -1660,19 +1624,13 @@ pub enum AssocTyConstraintKind {
     },
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Ty {
     pub id: NodeId,
     pub kind: TyKind,
     pub span: Span,
 }
 
-impl fmt::Debug for Ty {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "type({})", pprust::ty_to_string(self))
-    }
-}
-
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct BareFnTy {
     pub unsafety: Unsafety,
diff --git a/src/libsyntax/attr/builtin.rs b/src/libsyntax/attr/builtin.rs
index 2a8e6b2cc95..efc48256e7c 100644
--- a/src/libsyntax/attr/builtin.rs
+++ b/src/libsyntax/attr/builtin.rs
@@ -5,6 +5,7 @@ use crate::early_buffered_lints::BufferedEarlyLintId;
 use crate::ext::base::ExtCtxt;
 use crate::feature_gate::{Features, GatedCfg};
 use crate::parse::ParseSess;
+use crate::print::pprust;
 
 use errors::{Applicability, Handler};
 use syntax_pos::hygiene::Transparency;
@@ -243,7 +244,11 @@ fn find_stability_generic<'a, I>(sess: &ParseSess,
             let meta = meta.as_ref().unwrap();
             let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
                 if item.is_some() {
-                    handle_errors(sess, meta.span, AttrError::MultipleItem(meta.path.to_string()));
+                    handle_errors(
+                        sess,
+                        meta.span,
+                        AttrError::MultipleItem(pprust::path_to_string(&meta.path)),
+                    );
                     return false
                 }
                 if let Some(v) = meta.value_str() {
@@ -271,7 +276,10 @@ fn find_stability_generic<'a, I>(sess: &ParseSess,
                                     handle_errors(
                                         sess,
                                         mi.span,
-                                        AttrError::UnknownMetaItem(mi.path.to_string(), expected),
+                                        AttrError::UnknownMetaItem(
+                                            pprust::path_to_string(&mi.path),
+                                            expected,
+                                        ),
                                     );
                                     continue 'outer
                                 }
@@ -362,7 +370,7 @@ fn find_stability_generic<'a, I>(sess: &ParseSess,
                                         sess,
                                         meta.span(),
                                         AttrError::UnknownMetaItem(
-                                            mi.path.to_string(),
+                                            pprust::path_to_string(&mi.path),
                                             &["feature", "reason", "issue", "soft"]
                                         ),
                                     );
@@ -434,7 +442,8 @@ fn find_stability_generic<'a, I>(sess: &ParseSess,
                                             sess,
                                             meta.span(),
                                             AttrError::UnknownMetaItem(
-                                                mi.path.to_string(), &["since", "note"],
+                                                pprust::path_to_string(&mi.path),
+                                                &["since", "note"],
                                             ),
                                         );
                                         continue 'outer
@@ -597,8 +606,11 @@ pub fn eval_condition<F>(cfg: &ast::MetaItem, sess: &ParseSess, eval: &mut F)
                     !eval_condition(mis[0].meta_item().unwrap(), sess, eval)
                 },
                 _ => {
-                    span_err!(sess.span_diagnostic, cfg.span, E0537,
-                              "invalid predicate `{}`", cfg.path);
+                    span_err!(
+                        sess.span_diagnostic, cfg.span, E0537,
+                        "invalid predicate `{}`",
+                        pprust::path_to_string(&cfg.path)
+                    );
                     false
                 }
             }
@@ -653,7 +665,9 @@ fn find_deprecation_generic<'a, I>(sess: &ParseSess,
                 let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
                     if item.is_some() {
                         handle_errors(
-                            sess, meta.span, AttrError::MultipleItem(meta.path.to_string())
+                            sess,
+                            meta.span,
+                            AttrError::MultipleItem(pprust::path_to_string(&meta.path)),
                         );
                         return false
                     }
@@ -691,8 +705,10 @@ fn find_deprecation_generic<'a, I>(sess: &ParseSess,
                                     handle_errors(
                                         sess,
                                         meta.span(),
-                                        AttrError::UnknownMetaItem(mi.path.to_string(),
-                                                                   &["since", "note"]),
+                                        AttrError::UnknownMetaItem(
+                                            pprust::path_to_string(&mi.path),
+                                            &["since", "note"],
+                                        ),
                                     );
                                     continue 'outer
                                 }
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index bbd8da2acef..1e44f3dd5e5 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -13,6 +13,7 @@ use crate::mut_visit::*;
 use crate::parse::{DirectoryOwnership, PResult, ParseSess};
 use crate::parse::token;
 use crate::parse::parser::Parser;
+use crate::print::pprust;
 use crate::ptr::P;
 use crate::symbol::{sym, Symbol};
 use crate::tokenstream::{TokenStream, TokenTree};
@@ -388,7 +389,8 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                             "`derive` may only be applied to structs, enums and unions");
                         if let ast::AttrStyle::Inner = attr.style {
                             let trait_list = derives.iter()
-                                .map(|t| t.to_string()).collect::<Vec<_>>();
+                                .map(|t| pprust::path_to_string(t))
+                                .collect::<Vec<_>>();
                             let suggestion = format!("#[derive({})]", trait_list.join(", "));
                             err.span_suggestion(
                                 span, "try an outer attribute", suggestion,
@@ -587,8 +589,11 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     let result = if let Some(result) = fragment_kind.make_from(tok_result) {
                         result
                     } else {
-                        let msg = format!("non-{kind} macro in {kind} position: {path}",
-                                          kind = fragment_kind.name(), path = mac.path);
+                        let msg = format!(
+                            "non-{kind} macro in {kind} position: {path}",
+                            kind = fragment_kind.name(),
+                            path = pprust::path_to_string(&mac.path),
+                        );
                         self.cx.span_err(span, &msg);
                         self.cx.trace_macros_diag();
                         fragment_kind.dummy(span)
@@ -878,7 +883,7 @@ impl<'a> Parser<'a> {
             err.span_label(span, "caused by the macro expansion here");
             let msg = format!(
                 "the usage of `{}!` is likely invalid in {} context",
-                macro_path,
+                pprust::path_to_string(&macro_path),
                 kind_name,
             );
             err.note(&msg);
diff --git a/src/libsyntax/ext/mbe/macro_rules.rs b/src/libsyntax/ext/mbe/macro_rules.rs
index aec4a683141..e4fc269d147 100644
--- a/src/libsyntax/ext/mbe/macro_rules.rs
+++ b/src/libsyntax/ext/mbe/macro_rules.rs
@@ -174,7 +174,8 @@ fn generic_extension<'cx>(
     rhses: &[mbe::TokenTree],
 ) -> Box<dyn MacResult + 'cx> {
     if cx.trace_macros() {
-        trace_macros_note(cx, sp, format!("expanding `{}! {{ {} }}`", name, arg));
+        let msg = format!("expanding `{}! {{ {} }}`", name, pprust::tts_to_string(arg.clone()));
+        trace_macros_note(cx, sp, msg);
     }
 
     // Which arm's failure should we report? (the one furthest along)
@@ -212,7 +213,8 @@ fn generic_extension<'cx>(
                 }
 
                 if cx.trace_macros() {
-                    trace_macros_note(cx, sp, format!("to `{}`", tts));
+                    let msg = format!("to `{}`", pprust::tts_to_string(tts.clone()));
+                    trace_macros_note(cx, sp, msg);
                 }
 
                 let directory = Directory {
diff --git a/src/libsyntax/ext/proc_macro_server.rs b/src/libsyntax/ext/proc_macro_server.rs
index 021ec46d987..3ed6f4114ae 100644
--- a/src/libsyntax/ext/proc_macro_server.rs
+++ b/src/libsyntax/ext/proc_macro_server.rs
@@ -2,6 +2,7 @@ use crate::ast;
 use crate::ext::base::ExtCtxt;
 use crate::parse::{self, token, ParseSess};
 use crate::parse::lexer::comments;
+use crate::print::pprust;
 use crate::tokenstream::{self, DelimSpan, IsJoint::*, TokenStream, TreeAndJoint};
 
 use errors::Diagnostic;
@@ -407,7 +408,7 @@ impl server::TokenStream for Rustc<'_> {
         )
     }
     fn to_string(&mut self, stream: &Self::TokenStream) -> String {
-        stream.to_string()
+        pprust::tts_to_string(stream.clone())
     }
     fn from_token_tree(
         &mut self,
diff --git a/src/libsyntax/parse/diagnostics.rs b/src/libsyntax/parse/diagnostics.rs
index 42cbe28fc17..0bbd67589dd 100644
--- a/src/libsyntax/parse/diagnostics.rs
+++ b/src/libsyntax/parse/diagnostics.rs
@@ -856,7 +856,7 @@ impl<'a> Parser<'a> {
                 // This is a best-effort recovery.
                 path.span,
                 "try",
-                format!("<{}>::{}", ty_str, path),
+                format!("<{}>::{}", ty_str, pprust::path_to_string(&path)),
                 Applicability::MaybeIncorrect,
             )
             .emit();
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 920208c8fd9..400bf0f3856 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -1177,12 +1177,14 @@ impl<'a> Parser<'a> {
 `pub(super)`: visible only in the current module's parent
 `pub(in path::to::module)`: visible only on the specified path"##;
 
+        let path_str = pprust::path_to_string(&path);
+
         struct_span_err!(self.sess.span_diagnostic, path.span, E0704, "{}", msg)
             .help(suggestion)
             .span_suggestion(
                 path.span,
-                &format!("make this visible only to module `{}` with `in`", path),
-                format!("in {}", path),
+                &format!("make this visible only to module `{}` with `in`", path_str),
+                format!("in {}", path_str),
                 Applicability::MachineApplicable,
             )
             .emit();
diff --git a/src/libsyntax/parse/parser/expr.rs b/src/libsyntax/parse/parser/expr.rs
index b459782d237..660bf9b7d65 100644
--- a/src/libsyntax/parse/parser/expr.rs
+++ b/src/libsyntax/parse/parser/expr.rs
@@ -552,8 +552,11 @@ impl<'a> Parser<'a> {
 
                         // Report non-fatal diagnostics, keep `x as usize` as an expression
                         // in AST and continue parsing.
-                        let msg = format!("`<` is interpreted as a start of generic \
-                                           arguments for `{}`, not a {}", path, op_noun);
+                        let msg = format!(
+                            "`<` is interpreted as a start of generic arguments for `{}`, not a {}",
+                            pprust::path_to_string(&path),
+                            op_noun,
+                        );
                         let span_after_type = parser_snapshot_after_type.token.span;
                         let expr = mk_expr(self, P(Ty {
                             span: path.span,
diff --git a/src/libsyntax/tokenstream.rs b/src/libsyntax/tokenstream.rs
index bef12ed4fad..970bacdde13 100644
--- a/src/libsyntax/tokenstream.rs
+++ b/src/libsyntax/tokenstream.rs
@@ -14,7 +14,6 @@
 //! ownership of the original.
 
 use crate::parse::token::{self, DelimToken, Token, TokenKind};
-use crate::print::pprust;
 
 use syntax_pos::{BytePos, Span, DUMMY_SP};
 #[cfg(target_arch = "x86_64")]
@@ -23,7 +22,7 @@ use rustc_data_structures::sync::Lrc;
 use rustc_serialize::{Decoder, Decodable, Encoder, Encodable};
 use smallvec::{SmallVec, smallvec};
 
-use std::{fmt, iter, mem};
+use std::{iter, mem};
 
 #[cfg(test)]
 mod tests;
@@ -507,12 +506,6 @@ impl Cursor {
     }
 }
 
-impl fmt::Display for TokenStream {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(&pprust::tts_to_string(self.clone()))
-    }
-}
-
 impl Encodable for TokenStream {
     fn encode<E: Encoder>(&self, encoder: &mut E) -> Result<(), E::Error> {
         self.trees().collect::<Vec<_>>().encode(encoder)