Auto merge of rust-lang#3336 - RalfJung:rustup, r=RalfJung

Rustup

Also add regression test for rust-lang#121508.

Cargo.lock

@@ -1640,9 +1640,9 @@ checksum = "95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8"
 
 [[package]]
 name = "hermit-abi"
-version = "0.3.6"
+version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bd5256b483761cd23699d0da46cc6fd2ee3be420bbe6d020ae4a091e70b7e9fd"
+checksum = "d231dfb89cfffdbc30e7fc41579ed6066ad03abda9e567ccafae602b97ec5024"
 dependencies = [
  "compiler_builtins",
  "rustc-std-workspace-alloc",

compiler/rustc_builtin_macros/src/errors.rs

@@ -136,27 +136,6 @@ pub(crate) struct BenchSig {
     pub(crate) span: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag(builtin_macros_test_arg_non_lifetime)]
-pub(crate) struct TestArgNonLifetime {
-    #[primary_span]
-    pub(crate) span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(builtin_macros_should_panic)]
-pub(crate) struct ShouldPanic {
-    #[primary_span]
-    pub(crate) span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(builtin_macros_test_args)]
-pub(crate) struct TestArgs {
-    #[primary_span]
-    pub(crate) span: Span,
-}
-
 #[derive(Diagnostic)]
 #[diag(builtin_macros_alloc_must_statics)]
 pub(crate) struct AllocMustStatics {

compiler/rustc_errors/src/diagnostic.rs

@@ -108,6 +108,25 @@ impl EmissionGuarantee for rustc_span::fatal_error::FatalError {
 
 /// Trait implemented by error types. This is rarely implemented manually. Instead, use
 /// `#[derive(Diagnostic)]` -- see [rustc_macros::Diagnostic].
+///
+/// When implemented manually, it should be generic over the emission
+/// guarantee, i.e.:
+/// ```ignore (fragment)
+/// impl<'a, G: EmissionGuarantee> IntoDiagnostic<'a, G> for Foo { ... }
+/// ```
+/// rather than being specific:
+/// ```ignore (fragment)
+/// impl<'a> IntoDiagnostic<'a> for Bar { ... }  // the default type param is `ErrorGuaranteed`
+/// impl<'a> IntoDiagnostic<'a, ()> for Baz { ... }
+/// ```
+/// There are two reasons for this.
+/// - A diagnostic like `Foo` *could* be emitted at any level -- `level` is
+///   passed in to `into_diagnostic` from outside. Even if in practice it is
+///   always emitted at a single level, we let the diagnostic creation/emission
+///   site determine the level (by using `create_err`, `emit_warn`, etc.)
+///   rather than the `IntoDiagnostic` impl.
+/// - Derived impls are always generic, and it's good for the hand-written
+///   impls to be consistent with them.
 #[rustc_diagnostic_item = "IntoDiagnostic"]
 pub trait IntoDiagnostic<'a, G: EmissionGuarantee = ErrorGuaranteed> {
     /// Write out as a diagnostic out of `DiagCtxt`.
@@ -1289,11 +1308,9 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         drop(self);
     }
 
-    /// Stashes diagnostic for possible later improvement in a different,
-    /// later stage of the compiler. The diagnostic can be accessed with
-    /// the provided `span` and `key` through [`DiagCtxt::steal_diagnostic()`].
-    pub fn stash(mut self, span: Span, key: StashKey) {
-        self.dcx.stash_diagnostic(span, key, self.take_diag());
+    /// See `DiagCtxt::stash_diagnostic` for details.
+    pub fn stash(mut self, span: Span, key: StashKey) -> Option<ErrorGuaranteed> {
+        self.dcx.stash_diagnostic(span, key, self.take_diag())
     }
 
     /// Delay emission of this diagnostic as a bug.