Emit specific message for time<=0.3.35

compiler/rustc_span/src/symbol.rs

@@ -1896,6 +1896,7 @@ symbols! {
         three_way_compare,
         thumb2,
         thumb_mode: "thumb-mode",
+        time,
         tmm_reg,
         to_owned_method,
         to_string,

compiler/rustc_trait_selection/messages.ftl

@@ -446,6 +446,8 @@ trait_selection_type_annotations_needed = {$source_kind ->
 }
     .label = type must be known at this point
 
+trait_selection_type_annotations_needed_error_time = this is an inference error on crate `time` caused by an API change in Rust 1.80.0; update `time` to version `>=0.3.35` by calling `cargo update`
+
 trait_selection_types_declared_different = these two types are declared with different lifetimes...
 
 trait_selection_unable_to_construct_constant_value = unable to construct a constant value for the unevaluated constant {$unevaluated}

compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs

@@ -6,7 +6,7 @@ use rustc_errors::codes::*;
 use rustc_errors::{Diag, IntoDiagArg};
 use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind, Namespace, Res};
-use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{Body, Closure, Expr, ExprKind, FnRetTy, HirId, LetStmt, LocalSource};
 use rustc_middle::bug;
@@ -18,7 +18,7 @@ use rustc_middle::ty::{
     TypeFoldable, TypeFolder, TypeSuperFoldable, TypeckResults,
 };
 use rustc_span::symbol::{sym, Ident};
-use rustc_span::{BytePos, Span, DUMMY_SP};
+use rustc_span::{BytePos, FileName, Span, DUMMY_SP};
 
 use crate::error_reporting::TypeErrCtxt;
 use crate::errors::{
@@ -384,6 +384,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 bad_label,
                 was_written: false,
                 path: Default::default(),
+                time_version: false,
             }),
             TypeAnnotationNeeded::E0283 => self.dcx().create_err(AmbiguousImpl {
                 span,
@@ -577,6 +578,10 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 }
             }
         }
+
+        let time_version =
+            self.detect_old_time_crate_version(failure_span, &kind, &mut infer_subdiags);
+
         match error_code {
             TypeAnnotationNeeded::E0282 => self.dcx().create_err(AnnotationRequired {
                 span,
@@ -588,6 +593,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 bad_label: None,
                 was_written: path.is_some(),
                 path: path.unwrap_or_default(),
+                time_version,
             }),
             TypeAnnotationNeeded::E0283 => self.dcx().create_err(AmbiguousImpl {
                 span,
@@ -613,6 +619,42 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             }),
         }
     }
+
+    /// Detect the inference regression on crate `time` <= 0.3.35 and emit a more targeted error.
+    /// <https://github.com/rust-lang/rust/issues/127343>
+    // FIXME: we should figure out a more generic version of doing this, ideally in cargo itself.
+    fn detect_old_time_crate_version(
+        &self,
+        span: Option<Span>,
+        kind: &InferSourceKind<'_>,
+        // We will clear the non-actionable suggestion from the error to reduce noise.
+        infer_subdiags: &mut Vec<SourceKindSubdiag<'_>>,
+    ) -> bool {
+        // FIXME(#129461): We are time-boxing this code in the compiler. It'll start failing
+        // compilation once we promote 1.89 to beta, which will happen in 9 months from now.
+        #[cfg(not(version("1.89")))]
+        const fn version_check() {}
+        #[cfg(version("1.89"))]
+        const fn version_check() {
+            panic!("remove this check as presumably the ecosystem has moved from needing it");
+        }
+        const { version_check() };
+        // Only relevant when building the `time` crate.
+        if self.infcx.tcx.crate_name(LOCAL_CRATE) == sym::time
+            && let Some(span) = span
+            && let InferSourceKind::LetBinding { pattern_name, .. } = kind
+            && let Some(name) = pattern_name
+            && name.as_str() == "items"
+            && let FileName::Real(file) = self.infcx.tcx.sess.source_map().span_to_filename(span)
+        {
+            let path = file.local_path_if_available().to_string_lossy();
+            if path.contains("format_description") && path.contains("parse") {
+                infer_subdiags.clear();
+                return true;
+            }
+        }
+        false
+    }
 }
 
 #[derive(Debug)]

compiler/rustc_trait_selection/src/errors.rs

@@ -205,6 +205,8 @@ pub struct AnnotationRequired<'a> {
     #[note(trait_selection_full_type_written)]
     pub was_written: bool,
     pub path: PathBuf,
+    #[note(trait_selection_type_annotations_needed_error_time)]
+    pub time_version: bool,
 }
 
 // Copy of `AnnotationRequired` for E0283

compiler/rustc_trait_selection/src/lib.rs

@@ -19,6 +19,7 @@
 #![feature(assert_matches)]
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
+#![feature(cfg_version)]
 #![feature(control_flow_enum)]
 #![feature(extract_if)]
 #![feature(if_let_guard)]

tests/ui/inference/detect-old-time-version-format_description-parse.rs

@@ -0,0 +1,8 @@
+#![crate_name = "time"]
+
+fn main() {
+    let items = Box::new(vec![]); //~ ERROR E0282
+    //~^ NOTE type must be known at this point
+    //~| NOTE this is an inference error on crate `time` caused by an API change in Rust 1.80.0; update `time` to version `>=0.3.35`
+    items.into();
+}

tests/ui/inference/detect-old-time-version-format_description-parse.stderr

@@ -0,0 +1,11 @@
+error[E0282]: type annotations needed for `Box<Vec<_>>`
+  --> $DIR/detect-old-time-version-format_description-parse.rs:4:9
+   |
+LL |     let items = Box::new(vec![]);
+   |         ^^^^^   ---------------- type must be known at this point
+   |
+   = note: this is an inference error on crate `time` caused by an API change in Rust 1.80.0; update `time` to version `>=0.3.35` by calling `cargo update`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0282`.