Rollup merge of #121669 - nnethercote:count-stashed-errs-again, r=estebank

Count stashed errors again

Stashed diagnostics are such a pain. Their "might be emitted, might not" semantics messes with lots of things.

#120828 and #121206 made some big changes to how they work, improving some things, but still leaving some problems, as seen by the issues caused by #121206. This PR aims to fix all of them by restricting them in a way that eliminates the "might be emitted, might not" semantics while still allowing 98% of their benefit. Details in the individual commit logs.

r? `@oli-obk`

5 files changed, 25 insertions, 23 deletions

diff --git a/src/tools/clippy/tests/ui/crashes/unreachable-array-or-slice.rs b/src/tools/clippy/tests/ui/crashes/unreachable-array-or-slice.rs
new file mode 100644
index 00000000000..b56abccbd41
--- /dev/null
+++ b/src/tools/clippy/tests/ui/crashes/unreachable-array-or-slice.rs
@@ -0,0 +1,8 @@
+struct Foo(isize, isize, isize, isize);
+
+pub fn main() {
+    let Self::anything_here_kills_it(a, b, ..) = Foo(5, 5, 5, 5);
+    match [5, 5, 5, 5] {
+        [..] => { }
+    }
+}
diff --git a/src/tools/clippy/tests/ui/crashes/unreachable-array-or-slice.stderr b/src/tools/clippy/tests/ui/crashes/unreachable-array-or-slice.stderr
new file mode 100644
index 00000000000..9e0d3b934b8
--- /dev/null
+++ b/src/tools/clippy/tests/ui/crashes/unreachable-array-or-slice.stderr
@@ -0,0 +1,9 @@
+error[E0433]: failed to resolve: `Self` is only available in impls, traits, and type definitions
+  --> tests/ui/crashes/unreachable-array-or-slice.rs:4:9
+   |
+LL |     let Self::anything_here_kills_it(a, b, ..) = Foo(5, 5, 5, 5);
+   |         ^^^^ `Self` is only available in impls, traits, and type definitions
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0433`.
diff --git a/src/tools/miri/src/bin/miri.rs b/src/tools/miri/src/bin/miri.rs
index 8a7133fea43..281a32b77c5 100644
--- a/src/tools/miri/src/bin/miri.rs
+++ b/src/tools/miri/src/bin/miri.rs
@@ -68,7 +68,7 @@ impl rustc_driver::Callbacks for MiriCompilerCalls {
         queries: &'tcx rustc_interface::Queries<'tcx>,
     ) -> Compilation {
         queries.global_ctxt().unwrap().enter(|tcx| {
-            if tcx.sess.dcx().has_errors().is_some() {
+            if tcx.sess.dcx().has_errors_or_delayed_bugs().is_some() {
                 tcx.dcx().fatal("miri cannot be run on programs that fail compilation");
             }
 
diff --git a/src/tools/rustfmt/src/formatting.rs b/src/tools/rustfmt/src/formatting.rs
index 323ae83fe6e..1c64921b1a6 100644
--- a/src/tools/rustfmt/src/formatting.rs
+++ b/src/tools/rustfmt/src/formatting.rs
@@ -109,7 +109,7 @@ fn format_project<T: FormatHandler>(
     let main_file = input.file_name();
     let input_is_stdin = main_file == FileName::Stdin;
 
-    let mut parse_session = ParseSess::new(config)?;
+    let parse_session = ParseSess::new(config)?;
     if config.skip_children() && parse_session.ignore_file(&main_file) {
         return Ok(FormatReport::new());
     }
@@ -118,20 +118,11 @@ fn format_project<T: FormatHandler>(
     let mut report = FormatReport::new();
     let directory_ownership = input.to_directory_ownership();
 
-    // rustfmt doesn't use `run_compiler` like other tools, so it must emit any
-    // stashed diagnostics itself, otherwise the `DiagCtxt` will assert when
-    // dropped. The final result here combines the parsing result and the
-    // `emit_stashed_diagnostics` result.
-    let parse_res = Parser::parse_crate(input, &parse_session);
-    let stashed_res = parse_session.emit_stashed_diagnostics();
-    let krate = match (parse_res, stashed_res) {
-        (Ok(krate), None) => krate,
-        (parse_res, _) => {
-            // Surface parse error via Session (errors are merged there from report).
-            let forbid_verbose = match parse_res {
-                Err(e) if e != ParserError::ParsePanicError => true,
-                _ => input_is_stdin,
-            };
+    let krate = match Parser::parse_crate(input, &parse_session) {
+        Ok(krate) => krate,
+        // Surface parse error via Session (errors are merged there from report)
+        Err(e) => {
+            let forbid_verbose = input_is_stdin || e != ParserError::ParsePanicError;
             should_emit_verbose(forbid_verbose, config, || {
                 eprintln!("The Rust parser panicked");
             });
diff --git a/src/tools/rustfmt/src/parse/session.rs b/src/tools/rustfmt/src/parse/session.rs
index e33f1ca755c..f5defe63c13 100644
--- a/src/tools/rustfmt/src/parse/session.rs
+++ b/src/tools/rustfmt/src/parse/session.rs
@@ -5,9 +5,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use rustc_data_structures::sync::{IntoDynSyncSend, Lrc};
 use rustc_errors::emitter::{DynEmitter, Emitter, HumanEmitter};
 use rustc_errors::translation::Translate;
-use rustc_errors::{
-    ColorConfig, Diag, DiagCtxt, DiagInner, ErrorGuaranteed, Level as DiagnosticLevel,
-};
+use rustc_errors::{ColorConfig, Diag, DiagCtxt, DiagInner, Level as DiagnosticLevel};
 use rustc_session::parse::ParseSess as RawParseSess;
 use rustc_span::{
     source_map::{FilePathMapping, SourceMap},
@@ -230,10 +228,6 @@ impl ParseSess {
         self.ignore_path_set.as_ref().is_match(path)
     }
 
-    pub(crate) fn emit_stashed_diagnostics(&mut self) -> Option<ErrorGuaranteed> {
-        self.parse_sess.dcx.emit_stashed_diagnostics()
-    }
-
     pub(crate) fn set_silent_emitter(&mut self) {
         self.parse_sess.dcx = DiagCtxt::with_emitter(silent_emitter());
     }