Auto merge of #82263 - Dylan-DPC:rollup-cypm2uw, r=Dylan-DPC

Rollup of 10 pull requests

Successful merges:

 - #81546 ([libtest] Run the test synchronously when hitting thread limit)
 - #82066 (Ensure valid TraitRefs are created for GATs)
 - #82112 (const_generics: Dont evaluate array length const when handling yet another error )
 - #82194 (In some limited cases, suggest `where` bounds for non-type params)
 - #82215 (Replace if-let and while-let with `if let` and `while let`)
 - #82218 (Make sure pdbs are copied along with exe and dlls when bootstrapping)
 - #82236 (avoid converting types into themselves (clippy::useless_conversion))
 - #82246 (Add long explanation for E0549)
 - #82248 (Optimize counting digits in line numbers during error reporting)
 - #82256 (Print -Ztime-passes (and misc stats/logs) on stderr, not stdout.)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -914,6 +914,7 @@ impl<'a> State<'a> {
 
     pub fn print_assoc_constraint(&mut self, constraint: &ast::AssocTyConstraint) {
         self.print_ident(constraint.ident);
+        constraint.gen_args.as_ref().map(|args| self.print_generic_args(args, false));
         self.s.space();
         match &constraint.kind {
             ast::AssocTyConstraintKind::Equality { ty } => {

compiler/rustc_data_structures/src/profiling.rs

@@ -608,7 +608,7 @@ pub fn print_time_passes_entry(
         (None, None) => String::new(),
     };
 
-    println!("time: {:>7}{}\t{}", duration_to_secs_str(dur), mem_string, what);
+    eprintln!("time: {:>7}{}\t{}", duration_to_secs_str(dur), mem_string, what);
 }
 
 // Hack up our own formatting for the duration to make it easier for scripts

compiler/rustc_error_codes/src/error_codes.rs

@@ -290,6 +290,7 @@ E0543: include_str!("./error_codes/E0543.md"),
 E0545: include_str!("./error_codes/E0545.md"),
 E0546: include_str!("./error_codes/E0546.md"),
 E0547: include_str!("./error_codes/E0547.md"),
+E0549: include_str!("./error_codes/E0549.md"),
 E0550: include_str!("./error_codes/E0550.md"),
 E0551: include_str!("./error_codes/E0551.md"),
 E0552: include_str!("./error_codes/E0552.md"),
@@ -608,9 +609,6 @@ E0781: include_str!("./error_codes/E0781.md"),
 //  E0540, // multiple rustc_deprecated attributes
     E0544, // multiple stability levels
 //  E0548, // replaced with a generic attribute input check
-    // rustc_deprecated attribute must be paired with either stable or unstable
-    // attribute
-    E0549,
     E0553, // multiple rustc_const_unstable attributes
 //  E0555, // replaced with a generic attribute input check
 //  E0558, // replaced with a generic attribute input check

compiler/rustc_error_codes/src/error_codes/E0162.md

@@ -1,6 +1,6 @@
 #### Note: this error code is no longer emitted by the compiler.
 
-An if-let pattern attempts to match the pattern, and enters the body if the
+An `if let` pattern attempts to match the pattern, and enters the body if the
 match was successful. If the match is irrefutable (when it cannot fail to
 match), use a regular `let`-binding instead. For instance:
 

compiler/rustc_error_codes/src/error_codes/E0165.md

@@ -1,6 +1,6 @@
 #### Note: this error code is no longer emitted by the compiler.
 
-A while-let pattern attempts to match the pattern, and enters the body if the
+A `while let` pattern attempts to match the pattern, and enters the body if the
 match was successful. If the match is irrefutable (when it cannot fail to
 match), use a regular `let`-binding inside a `loop` instead. For instance:
 

compiler/rustc_error_codes/src/error_codes/E0549.md

@@ -0,0 +1,37 @@
+A `rustc_deprecated` attribute wasn't paired with a `stable`/`unstable`
+attribute.
+
+Erroneous code example:
+
+```compile_fail,E0549
+#![feature(staged_api)]
+#![stable(since = "1.0.0", feature = "test")]
+
+#[rustc_deprecated(
+    since = "1.0.1",
+    reason = "explanation for deprecation"
+)] // invalid
+fn _deprecated_fn() {}
+```
+
+To fix this issue, you need to add also an attribute `stable` or `unstable`.
+Example:
+
+```
+#![feature(staged_api)]
+#![stable(since = "1.0.0", feature = "test")]
+
+#[stable(since = "1.0.0", feature = "test")]
+#[rustc_deprecated(
+    since = "1.0.1",
+    reason = "explanation for deprecation"
+)] // ok!
+fn _deprecated_fn() {}
+```
+
+See the [How Rust is Made and “Nightly Rust”][how-rust-made-nightly] appendix
+of the Book and the [Stability attributes][stability-attributes] section of the
+Rustc Dev Guide for more details.
+
+[how-rust-made-nightly]: https://doc.rust-lang.org/book/appendix-07-nightly-rust.html
+[stability-attributes]: https://rustc-dev-guide.rust-lang.org/stability.html

compiler/rustc_errors/src/emitter.rs

@@ -1713,7 +1713,18 @@ impl EmitterWriter {
         let max_line_num_len = if self.ui_testing {
             ANONYMIZED_LINE_NUM.len()
         } else {
-            self.get_max_line_num(span, children).to_string().len()
+            // Instead of using .to_string().len(), we iteratively count the
+            // number of digits to avoid allocation. This strategy has sizable
+            // performance gains over the old string strategy.
+            let mut n = self.get_max_line_num(span, children);
+            let mut num_digits = 0;
+            loop {
+                num_digits += 1;
+                n /= 10;
+                if n == 0 {
+                    break num_digits;
+                }
+            }
         };
 
         match self.emit_message_default(span, message, code, level, max_line_num_len, false) {

compiler/rustc_hir/src/lang_items.rs

@@ -242,6 +242,7 @@ language_item_table! {
 
     Deref,                   sym::deref,               deref_trait,                Target::Trait;
     DerefMut,                sym::deref_mut,           deref_mut_trait,            Target::Trait;
+    DerefTarget,             sym::deref_target,        deref_target,               Target::AssocTy;
     Receiver,                sym::receiver,            receiver_trait,             Target::Trait;
 
     Fn,                      kw::Fn,                   fn_trait,                   Target::Trait;

compiler/rustc_incremental/src/persist/file_format.rs

@@ -109,7 +109,7 @@ fn report_format_mismatch(report_incremental_info: bool, file: &Path, message: &
     debug!("read_file: {}", message);
 
     if report_incremental_info {
-        println!(
+        eprintln!(
             "[incremental] ignoring cache artifact `{}`: {}",
             file.file_name().unwrap().to_string_lossy(),
             message

compiler/rustc_incremental/src/persist/fs.rs

@@ -440,12 +440,12 @@ fn copy_files(sess: &Session, target_dir: &Path, source_dir: &Path) -> Result<bo
     }
 
     if sess.opts.debugging_opts.incremental_info {
-        println!(
+        eprintln!(
             "[incremental] session directory: \
                   {} files hard-linked",
             files_linked
         );
-        println!(
+        eprintln!(
             "[incremental] session directory: \
                  {} files copied",
             files_copied