Auto merge of #58644 - Centril:rollup, r=Centril

Rollup of 17 pull requests

Successful merges:

 - #57656 (Deprecate the unstable Vec::resize_default)
 - #58059 (deprecate before_exec in favor of unsafe pre_exec)
 - #58064 (override `VecDeque::try_rfold`, also update iterator)
 - #58198 (Suggest removing parentheses surrounding lifetimes)
 - #58431 (fix overlapping references in BTree)
 - #58555 (Add a note about 2018e if someone uses `try {` in 2015e)
 - #58588 (remove a bit of dead code)
 - #58589 (cleanup macro after 2018 transition)
 - #58591 (Dedup a rustdoc diagnostic construction)
 - #58600 (fix small documentation typo)
 - #58601 (Search for target_triple.json only if builtin target not found)
 - #58606 (Docs: put Future trait into spotlight)
 - #58607 (Fixes #58586: Make E0505 erronous example fail for the 2018 edition)
 - #58615 (miri: explain why we use static alignment in ref-to-place conversion)
 - #58620 (introduce benchmarks of BTreeSet.intersection)
 - #58621 (Update miri links)
 - #58632 (Make std feature list sorted)

Failed merges:

r? @ghost

3 files changed, 17 insertions, 12 deletions

diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index 48f6e4c0c82..27b0cfb1630 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -9,12 +9,6 @@ use crate::ThinVec;
 use rustc_target::spec::abi::Abi;
 use syntax_pos::{Pos, Span, DUMMY_SP};
 
-// Transitional re-exports so qquote can find the paths it is looking for
-mod syntax {
-    pub use crate::ext;
-    pub use crate::parse;
-}
-
 pub trait AstBuilder {
     // paths
     fn path(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path;
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index d398437d7af..f50663f9785 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -36,10 +36,8 @@ macro_rules! ast_fragments {
     (
         $($Kind:ident($AstTy:ty) {
             $kind_name:expr;
-            // FIXME: HACK: this should be `$(one ...)?` and `$(many ...)?` but `?` macro
-            // repetition was removed from 2015 edition in #51587 because of ambiguities.
-            $(one fn $mut_visit_ast:ident; fn $visit_ast:ident;)*
-            $(many fn $flat_map_ast_elt:ident; fn $visit_ast_elt:ident;)*
+            $(one fn $mut_visit_ast:ident; fn $visit_ast:ident;)?
+            $(many fn $flat_map_ast_elt:ident; fn $visit_ast_elt:ident;)?
             fn $make_ast:ident;
         })*
     ) => {
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index b1fb38d8eaf..e6a48912c48 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -5503,6 +5503,7 @@ impl<'a> Parser<'a> {
             if is_bound_start {
                 let lo = self.span;
                 let has_parens = self.eat(&token::OpenDelim(token::Paren));
+                let inner_lo = self.span;
                 let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
                 if self.token.is_lifetime() {
                     if let Some(question_span) = question {
@@ -5511,9 +5512,21 @@ impl<'a> Parser<'a> {
                     }
                     bounds.push(GenericBound::Outlives(self.expect_lifetime()));
                     if has_parens {
+                        let inner_span = inner_lo.to(self.prev_span);
                         self.expect(&token::CloseDelim(token::Paren))?;
-                        self.span_err(self.prev_span,
-                                      "parenthesized lifetime bounds are not supported");
+                        let mut err = self.struct_span_err(
+                            lo.to(self.prev_span),
+                            "parenthesized lifetime bounds are not supported"
+                        );
+                        if let Ok(snippet) = self.sess.source_map().span_to_snippet(inner_span) {
+                            err.span_suggestion_short(
+                                lo.to(self.prev_span),
+                                "remove the parentheses",
+                                snippet.to_owned(),
+                                Applicability::MachineApplicable
+                            );
+                        }
+                        err.emit();
                     }
                 } else {
                     let lifetime_defs = self.parse_late_bound_lifetime_defs()?;