Auto merge of #108421 - Dylan-DPC:rollup-mpeovxd, r=Dylan-DPC

Rollup of 10 pull requests

Successful merges:

 - #106541 (implement const iterator using `rustc_do_not_const_check`)
 - #106918 (Rebuild BinaryHeap on unwind from retain)
 - #106923 (Restore behavior when primary bundle is missing)
 - #108169 (Make query keys `Copy`)
 - #108287 (Add test for bad cast with deferred projection equality)
 - #108370 (std: time: Avoid to use "was created" in elapsed() description)
 - #108377 (Fix ICE in 'duplicate diagnostic item' diagnostic)
 - #108388 (parser: provide better suggestions and errors on closures with braces missing)
 - #108391 (Fix `is_terminal`'s handling of long paths on Windows.)
 - #108401 (diagnostics: remove inconsistent English article "this" from E0107)

Failed merges:

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

Author: bors

compiler/rustc_error_messages/src/lib.rs

@@ -135,7 +135,10 @@ pub fn fluent_bundle(
 
     let fallback_locale = langid!("en-US");
     let requested_fallback_locale = requested_locale.as_ref() == Some(&fallback_locale);
-
+    trace!(?requested_fallback_locale);
+    if requested_fallback_locale && additional_ftl_path.is_none() {
+        return Ok(None);
+    }
     // If there is only `-Z additional-ftl-path`, assume locale is "en-US", otherwise use user
     // provided locale.
     let locale = requested_locale.clone().unwrap_or(fallback_locale);
@@ -153,7 +156,7 @@ pub fn fluent_bundle(
     bundle.set_use_isolating(with_directionality_markers);
 
     // If the user requests the default locale then don't try to load anything.
-    if !requested_fallback_locale && let Some(requested_locale) = requested_locale {
+    if let Some(requested_locale) = requested_locale {
         let mut found_resources = false;
         for sysroot in user_provided_sysroot.iter_mut().chain(sysroot_candidates.iter_mut()) {
             sysroot.push("share");

compiler/rustc_errors/src/translation.rs

@@ -1,4 +1,4 @@
-use crate::error::TranslateError;
+use crate::error::{TranslateError, TranslateErrorKind};
 use crate::snippet::Style;
 use crate::{DiagnosticArg, DiagnosticMessage, FluentBundle};
 use rustc_data_structures::sync::Lrc;
@@ -95,6 +95,16 @@ pub trait Translate {
                 // The primary bundle was present and translation succeeded
                 Some(Ok(t)) => t,
 
+                // If `translate_with_bundle` returns `Err` with the primary bundle, this is likely
+                // just that the primary bundle doesn't contain the message being translated, so
+                // proceed to the fallback bundle.
+                Some(Err(
+                    primary @ TranslateError::One {
+                        kind: TranslateErrorKind::MessageMissing, ..
+                    },
+                )) => translate_with_bundle(self.fallback_fluent_bundle())
+                    .map_err(|fallback| primary.and(fallback))?,
+
                 // Always yeet out for errors on debug (unless
                 // `RUSTC_TRANSLATION_NO_DEBUG_ASSERT` is set in the environment - this allows
                 // local runs of the test suites, of builds with debug assertions, to test the
@@ -106,9 +116,8 @@ pub trait Translate {
                     do yeet primary
                 }
 
-                // If `translate_with_bundle` returns `Err` with the primary bundle, this is likely
-                // just that the primary bundle doesn't contain the message being translated or
-                // something else went wrong) so proceed to the fallback bundle.
+                // ..otherwise, for end users, an error about this wouldn't be useful or actionable, so
+                // just hide it and try with the fallback bundle.
                 Some(Err(primary)) => translate_with_bundle(self.fallback_fluent_bundle())
                     .map_err(|fallback| primary.and(fallback))?,