Auto merge of #64510 - Centril:rollup-m03zsq8, r=Centril

Rollup of 10 pull requests

Successful merges:

 - #63955 (Make sure interned constants are immutable)
 - #64028 (Stabilize `Vec::new` and `String::new` as `const fn`s)
 - #64119 (ci: ensure all tool maintainers are assignable on issues)
 - #64444 (fix building libstd without backtrace feature)
 - #64446 (Fix build script sanitizer check.)
 - #64451 (when Miri tests are not passing, do not add Miri component)
 - #64467 (Hide diagnostics emitted during --cfg parsing)
 - #64497 (Don't print the "total" `-Ztime-passes` output if `--prints=...` is also given)
 - #64499 (Use `Symbol` in two more functions.)
 - #64504 (use println!() instead of println!(""))

Failed merges:

r? @ghost

1 files changed, 12 insertions, 1 deletions

diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index c74b2fee41d..723855c7c29 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -7,6 +7,7 @@ use crate::session::{early_error, early_warn, Session};
 use crate::session::search_paths::SearchPath;
 
 use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::sync::Lrc;
 
 use rustc_target::spec::{LinkerFlavor, MergeFunctions, PanicStrategy, RelroLevel};
 use rustc_target::spec::{Target, TargetTriple};
@@ -19,6 +20,7 @@ use syntax::parse::{ParseSess, new_parser_from_source_str};
 use syntax::parse::token;
 use syntax::symbol::{sym, Symbol};
 use syntax::feature_gate::UnstableFeatures;
+use syntax::source_map::SourceMap;
 
 use errors::emitter::HumanReadableErrorType;
 use errors::{ColorConfig, FatalError, Handler};
@@ -1850,11 +1852,20 @@ pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
     opts
 }
 
+struct NullEmitter;
+
+impl errors::emitter::Emitter for NullEmitter {
+    fn emit_diagnostic(&mut self, _: &errors::DiagnosticBuilder<'_>) {}
+}
+
 // Converts strings provided as `--cfg [cfgspec]` into a `crate_cfg`.
 pub fn parse_cfgspecs(cfgspecs: Vec<String>) -> FxHashSet<(String, Option<String>)> {
     syntax::with_default_globals(move || {
         let cfg = cfgspecs.into_iter().map(|s| {
-            let sess = ParseSess::new(FilePathMapping::empty());
+
+            let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
+            let handler = Handler::with_emitter(false, None, Box::new(NullEmitter));
+            let sess = ParseSess::with_span_handler(handler, cm);
             let filename = FileName::cfg_spec_source_code(&s);
             let mut parser = new_parser_from_source_str(&sess, filename, s.to_string());