Auto merge of #57155 - petrochenkov:dcrate3, r=dtolnay

Resolve `$crate`s for pretty-printing at more appropriate time

Doing it in `BuildReducedGraphVisitor` wasn't a good idea, identifiers wasn't actually visited half of the time.
As a result some `$crate`s weren't resolved and were therefore pretty-printed as `$crate` literally, which turns into two tokens during re-parsing of the pretty-printed text.

Now we are visiting and resolving `$crate` identifiers in an item right before sending that item to a proc macro attribute or derive.

Fixes #57089

Author: bors

src/librustc_resolve/build_reduced_graph.rs

@@ -1025,15 +1025,4 @@ impl<'a, 'b> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b> {
         }
         visit::walk_attribute(self, attr);
     }
-
-    fn visit_ident(&mut self, ident: Ident) {
-        if ident.name == keywords::DollarCrate.name() {
-            let name = match self.resolver.resolve_crate_root(ident).kind {
-                ModuleKind::Def(_, name) if name != keywords::Invalid.name() => name,
-                _ => keywords::Crate.name(),
-            };
-            ident.span.ctxt().set_dollar_crate_name(name);
-        }
-        visit::walk_ident(self, ident);
-    }
 }

src/librustc_resolve/macros.rs

@@ -1,6 +1,6 @@
 use {AmbiguityError, AmbiguityKind, AmbiguityErrorMisc};
 use {CrateLint, Resolver, ResolutionError, ScopeSet, Weak};
-use {Module, NameBinding, NameBindingKind, PathResult, Segment, ToNameBinding};
+use {Module, ModuleKind, NameBinding, NameBindingKind, PathResult, Segment, ToNameBinding};
 use {is_known_tool, resolve_error};
 use ModuleOrUniformRoot;
 use Namespace::*;
@@ -15,12 +15,13 @@ use syntax::ast::{self, Ident};
 use syntax::attr;
 use syntax::errors::DiagnosticBuilder;
 use syntax::ext::base::{self, Determinacy};
-use syntax::ext::base::{MacroKind, SyntaxExtension};
+use syntax::ext::base::{Annotatable, MacroKind, SyntaxExtension};
 use syntax::ext::expand::{AstFragment, Invocation, InvocationKind};
 use syntax::ext::hygiene::{self, Mark};
 use syntax::ext::tt::macro_rules;
 use syntax::feature_gate::{feature_err, is_builtin_attr_name, GateIssue};
 use syntax::symbol::{Symbol, keywords};
+use syntax::visit::Visitor;
 use syntax::util::lev_distance::find_best_match_for_name;
 use syntax_pos::{Span, DUMMY_SP};
 use errors::Applicability;
@@ -126,6 +127,26 @@ impl<'a> base::Resolver for Resolver<'a> {
         mark
     }
 
+    fn resolve_dollar_crates(&mut self, annotatable: &Annotatable) {
+        pub struct ResolveDollarCrates<'a, 'b: 'a> {
+            pub resolver: &'a mut Resolver<'b>,
+        }
+        impl<'a> Visitor<'a> for ResolveDollarCrates<'a, '_> {
+            fn visit_ident(&mut self, ident: Ident) {
+                if ident.name == keywords::DollarCrate.name() {
+                    let name = match self.resolver.resolve_crate_root(ident).kind {
+                        ModuleKind::Def(_, name) if name != keywords::Invalid.name() => name,
+                        _ => keywords::Crate.name(),
+                    };
+                    ident.span.ctxt().set_dollar_crate_name(name);
+                }
+            }
+            fn visit_mac(&mut self, _: &ast::Mac) {}
+        }
+
+        annotatable.visit_with(&mut ResolveDollarCrates { resolver: self });
+    }
+
     fn visit_ast_fragment_with_placeholders(&mut self, mark: Mark, fragment: &AstFragment,
                                             derives: &[Mark]) {
         let invocation = self.invocations[&mark];

src/libsyntax/ext/base.rs

@@ -14,6 +14,7 @@ use parse::token;
 use ptr::P;
 use smallvec::SmallVec;
 use symbol::{keywords, Ident, Symbol};
+use visit::Visitor;
 use ThinVec;
 
 use rustc_data_structures::fx::FxHashMap;
@@ -135,6 +136,17 @@ impl Annotatable {
             _ => false,
         }
     }
+
+    pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
+        match self {
+            Annotatable::Item(item) => visitor.visit_item(item),
+            Annotatable::TraitItem(trait_item) => visitor.visit_trait_item(trait_item),
+            Annotatable::ImplItem(impl_item) => visitor.visit_impl_item(impl_item),
+            Annotatable::ForeignItem(foreign_item) => visitor.visit_foreign_item(foreign_item),
+            Annotatable::Stmt(stmt) => visitor.visit_stmt(stmt),
+            Annotatable::Expr(expr) => visitor.visit_expr(expr),
+        }
+    }
 }
 
 // A more flexible ItemDecorator.
@@ -730,6 +742,7 @@ pub trait Resolver {
     fn next_node_id(&mut self) -> ast::NodeId;
     fn get_module_scope(&mut self, id: ast::NodeId) -> Mark;
 
+    fn resolve_dollar_crates(&mut self, annotatable: &Annotatable);
     fn visit_ast_fragment_with_placeholders(&mut self, mark: Mark, fragment: &AstFragment,
                                             derives: &[Mark]);
     fn add_builtin(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>);
@@ -763,6 +776,7 @@ impl Resolver for DummyResolver {
     fn next_node_id(&mut self) -> ast::NodeId { ast::DUMMY_NODE_ID }
     fn get_module_scope(&mut self, _id: ast::NodeId) -> Mark { Mark::root() }
 
+    fn resolve_dollar_crates(&mut self, _annotatable: &Annotatable) {}
     fn visit_ast_fragment_with_placeholders(&mut self, _invoc: Mark, _fragment: &AstFragment,
                                             _derives: &[Mark]) {}
     fn add_builtin(&mut self, _ident: ast::Ident, _ext: Lrc<SyntaxExtension>) {}

src/libsyntax/ext/expand.rs

@@ -574,6 +574,8 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 Some(invoc.fragment_kind.expect_from_annotatables(items))
             }
             AttrProcMacro(ref mac, ..) => {
+                // Resolve `$crate`s in case we have to go though stringification.
+                self.cx.resolver.resolve_dollar_crates(&item);
                 self.gate_proc_macro_attr_item(attr.span, &item);
                 let item_tok = TokenTree::Token(DUMMY_SP, Token::interpolated(match item {
                     Annotatable::Item(item) => token::NtItem(item),
@@ -915,6 +917,8 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
 
         match *ext {
             ProcMacroDerive(ref ext, ..) => {
+                // Resolve `$crate`s in case we have to go though stringification.
+                self.cx.resolver.resolve_dollar_crates(&item);
                 invoc.expansion_data.mark.set_expn_info(expn_info);
                 let span = span.with_ctxt(self.cx.backtrace());
                 let dummy = ast::MetaItem { // FIXME(jseyfried) avoid this

src/test/ui/proc-macro/auxiliary/dollar-crate.rs

@@ -6,6 +6,13 @@
 extern crate proc_macro;
 use proc_macro::TokenStream;
 
+#[proc_macro]
+pub fn m_empty(input: TokenStream) -> TokenStream {
+    println!("PROC MACRO INPUT (PRETTY-PRINTED): {}", input);
+    println!("PROC MACRO INPUT: {:#?}", input);
+    TokenStream::new()
+}
+
 #[proc_macro]
 pub fn m(input: TokenStream) -> TokenStream {
     println!("PROC MACRO INPUT (PRETTY-PRINTED): {}", input);

src/test/ui/proc-macro/dollar-crate-issue-57089.rs

@@ -0,0 +1,26 @@
+// compile-pass
+// edition:2018
+// aux-build:dollar-crate.rs
+
+// Anonymize unstable non-dummy spans while still showing dummy spans `0..0`.
+// normalize-stdout-test "bytes\([^0]\w*\.\.(\w+)\)" -> "bytes(LO..$1)"
+// normalize-stdout-test "bytes\((\w+)\.\.[^0]\w*\)" -> "bytes($1..HI)"
+
+extern crate dollar_crate;
+
+type S = u8;
+
+macro_rules! m {
+    () => {
+        dollar_crate::m_empty! {
+            struct M($crate::S);
+        }
+
+        #[dollar_crate::a]
+        struct A($crate::S);
+    };
+}
+
+m!();
+
+fn main() {}

src/test/ui/proc-macro/dollar-crate-issue-57089.stdout

@@ -0,0 +1,80 @@
+PROC MACRO INPUT (PRETTY-PRINTED): struct M ( $crate :: S ) ;
+PROC MACRO INPUT: TokenStream [
+    Ident {
+        ident: "struct",
+        span: #2 bytes(LO..HI)
+    },
+    Ident {
+        ident: "M",
+        span: #2 bytes(LO..HI)
+    },
+    Group {
+        delimiter: Parenthesis,
+        stream: TokenStream [
+            Ident {
+                ident: "$crate",
+                span: #2 bytes(LO..HI)
+            },
+            Punct {
+                ch: ':',
+                spacing: Joint,
+                span: #2 bytes(LO..HI)
+            },
+            Punct {
+                ch: ':',
+                spacing: Alone,
+                span: #2 bytes(LO..HI)
+            },
+            Ident {
+                ident: "S",
+                span: #2 bytes(LO..HI)
+            }
+        ],
+        span: #2 bytes(LO..HI)
+    },
+    Punct {
+        ch: ';',
+        spacing: Alone,
+        span: #2 bytes(LO..HI)
+    }
+]
+ATTRIBUTE INPUT (PRETTY-PRINTED): struct A(crate::S);
+ATTRIBUTE INPUT: TokenStream [
+    Ident {
+        ident: "struct",
+        span: #2 bytes(LO..HI)
+    },
+    Ident {
+        ident: "A",
+        span: #2 bytes(LO..HI)
+    },
+    Group {
+        delimiter: Parenthesis,
+        stream: TokenStream [
+            Ident {
+                ident: "$crate",
+                span: #2 bytes(LO..HI)
+            },
+            Punct {
+                ch: ':',
+                spacing: Joint,
+                span: #2 bytes(LO..HI)
+            },
+            Punct {
+                ch: ':',
+                spacing: Alone,
+                span: #2 bytes(LO..HI)
+            },
+            Ident {
+                ident: "S",
+                span: #2 bytes(LO..HI)
+            }
+        ],
+        span: #2 bytes(LO..HI)
+    },
+    Punct {
+        ch: ';',
+        spacing: Alone,
+        span: #2 bytes(LO..HI)
+    }
+]