Auto merge of #60903 - nnethercote:mv-gensyms-from-Symbol-to-Ident, r=petrochenkov

Move gensym operations from `Symbol` to `Ident`

Gensyms are always at the `Ident` level, and long-term we probably want to record gensym-ness in hygiene data.

r? @petrochenkov

5 files changed, 21 insertions, 27 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index b55ca453fb3..a6bb47bef87 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -72,11 +72,7 @@ pub struct Path {
 impl PartialEq<Symbol> for Path {
     fn eq(&self, symbol: &Symbol) -> bool {
         self.segments.len() == 1 && {
-            let name = self.segments[0].ident.name;
-            // Make sure these symbols are pure strings
-            debug_assert!(!symbol.is_gensymed());
-            debug_assert!(!name.is_gensymed());
-            name == *symbol
+            self.segments[0].ident.name == *symbol
         }
     }
 }
diff --git a/src/libsyntax/diagnostics/plugin.rs b/src/libsyntax/diagnostics/plugin.rs
index 21024eb41ef..c988dc61bec 100644
--- a/src/libsyntax/diagnostics/plugin.rs
+++ b/src/libsyntax/diagnostics/plugin.rs
@@ -7,7 +7,7 @@ use crate::ext::base::{ExtCtxt, MacEager, MacResult};
 use crate::ext::build::AstBuilder;
 use crate::parse::token;
 use crate::ptr::P;
-use crate::symbol::{keywords, Symbol};
+use crate::symbol::keywords;
 use crate::tokenstream::{TokenTree};
 
 use smallvec::smallvec;
@@ -121,13 +121,13 @@ pub fn expand_register_diagnostic<'cx>(ecx: &'cx mut ExtCtxt<'_>,
 
     let span = span.apply_mark(ecx.current_expansion.mark);
 
-    let sym = Ident::new(Symbol::gensym(&format!("__register_diagnostic_{}", code)), span);
+    let name = Ident::from_str_and_span(&format!("__register_diagnostic_{}", code), span).gensym();
 
     MacEager::items(smallvec![
         ecx.item_mod(
             span,
             span,
-            sym,
+            name,
             vec![],
             vec![],
         )
diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index 06651750de7..672b7b42855 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -252,8 +252,8 @@ pub fn compile(
     def: &ast::Item,
     edition: Edition
 ) -> SyntaxExtension {
-    let lhs_nm = ast::Ident::with_empty_ctxt(Symbol::gensym("lhs"));
-    let rhs_nm = ast::Ident::with_empty_ctxt(Symbol::gensym("rhs"));
+    let lhs_nm = ast::Ident::from_str("lhs").gensym();
+    let rhs_nm = ast::Ident::from_str("rhs").gensym();
 
     // Parse the macro_rules! invocation
     let body = match def.node {
diff --git a/src/libsyntax/std_inject.rs b/src/libsyntax/std_inject.rs
index 6784a2abe55..1be7986ad53 100644
--- a/src/libsyntax/std_inject.rs
+++ b/src/libsyntax/std_inject.rs
@@ -2,7 +2,7 @@ use crate::ast;
 use crate::attr;
 use crate::edition::Edition;
 use crate::ext::hygiene::{Mark, SyntaxContext};
-use crate::symbol::{Symbol, keywords, sym};
+use crate::symbol::{Ident, Symbol, keywords, sym};
 use crate::source_map::{ExpnInfo, MacroAttribute, dummy_spanned, hygiene, respan};
 use crate::ptr::P;
 use crate::tokenstream::TokenStream;
@@ -63,18 +63,15 @@ pub fn maybe_inject_crates_ref(
 
     // .rev() to preserve ordering above in combination with insert(0, ...)
     let alt_std_name = alt_std_name.map(Symbol::intern);
-    for orig_name in names.iter().rev() {
-        let orig_name = Symbol::intern(orig_name);
-        let mut rename = orig_name;
+    for orig_name_str in names.iter().rev() {
         // HACK(eddyb) gensym the injected crates on the Rust 2018 edition,
         // so they don't accidentally interfere with the new import paths.
-        if rust_2018 {
-            rename = orig_name.gensymed();
-        }
-        let orig_name = if rename != orig_name {
-            Some(orig_name)
+        let orig_name_sym = Symbol::intern(orig_name_str);
+        let orig_name_ident = Ident::with_empty_ctxt(orig_name_sym);
+        let (rename, orig_name) = if rust_2018 {
+            (orig_name_ident.gensym(), Some(orig_name_sym))
         } else {
-            None
+            (orig_name_ident, None)
         };
         krate.module.items.insert(0, P(ast::Item {
             attrs: vec![attr::mk_attr_outer(
@@ -84,7 +81,7 @@ pub fn maybe_inject_crates_ref(
             )],
             vis: dummy_spanned(ast::VisibilityKind::Inherited),
             node: ast::ItemKind::ExternCrate(alt_std_name.or(orig_name)),
-            ident: ast::Ident::with_empty_ctxt(rename),
+            ident: rename,
             id: ast::DUMMY_NODE_ID,
             span: DUMMY_SP,
             tokens: None,
diff --git a/src/libsyntax/test.rs b/src/libsyntax/test.rs
index 3fd0790161c..3dc7aad9459 100644
--- a/src/libsyntax/test.rs
+++ b/src/libsyntax/test.rs
@@ -232,11 +232,11 @@ fn mk_reexport_mod(cx: &mut TestCtxt<'_>,
         items,
     };
 
-    let sym = Ident::with_empty_ctxt(Symbol::gensym("__test_reexports"));
+    let name = Ident::from_str("__test_reexports").gensym();
     let parent = if parent == ast::DUMMY_NODE_ID { ast::CRATE_NODE_ID } else { parent };
     cx.ext_cx.current_expansion.mark = cx.ext_cx.resolver.get_module_scope(parent);
     let it = cx.ext_cx.monotonic_expander().flat_map_item(P(ast::Item {
-        ident: sym,
+        ident: name,
         attrs: Vec::new(),
         id: ast::DUMMY_NODE_ID,
         node: ast::ItemKind::Mod(reexport_mod),
@@ -245,7 +245,7 @@ fn mk_reexport_mod(cx: &mut TestCtxt<'_>,
         tokens: None,
     })).pop().unwrap();
 
-    (it, sym)
+    (it, name)
 }
 
 /// Crawl over the crate, inserting test reexports and the test main function
@@ -373,9 +373,10 @@ fn mk_main(cx: &mut TestCtxt<'_>) -> P<ast::Item> {
                            main_body);
 
     // Honor the reexport_test_harness_main attribute
-    let main_id = Ident::new(
-        cx.reexport_test_harness_main.unwrap_or(Symbol::gensym("main")),
-        sp);
+    let main_id = match cx.reexport_test_harness_main {
+        Some(sym) => Ident::new(sym, sp),
+        None => Ident::from_str_and_span("main", sp).gensym(),
+    };
 
     P(ast::Item {
         ident: main_id,