From d6abc203853480f7532755391203fc68f6245041 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Sun, 18 Aug 2024 18:59:26 +0000
Subject: [PATCH] Do not ICE on non-ADT rcvr type when looking for crate
 version collision

When looking for multiple versions of the same crate, do not blindly construct the receiver type.

Follow up to #128786. Fix #129205.
---
 .../rustc_hir_typeck/src/method/suggest.rs    | 16 ++++++++++++----
 .../missing-method-on-type-parameter.rs       |  5 +++++
 .../missing-method-on-type-parameter.stderr   | 19 +++++++++++++++++++
 3 files changed, 36 insertions(+), 4 deletions(-)
 create mode 100644 tests/ui/methods/missing-method-on-type-parameter.rs
 create mode 100644 tests/ui/methods/missing-method-on-type-parameter.stderr

diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs
index b3cf73bac1aa6..d6cf506285a58 100644
--- a/compiler/rustc_hir_typeck/src/method/suggest.rs
+++ b/compiler/rustc_hir_typeck/src/method/suggest.rs
@@ -3498,7 +3498,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 err,
                                 pick.item.def_id,
                                 rcvr.hir_id,
-                                *rcvr_ty,
+                                Some(*rcvr_ty),
                             );
                         if pick.autoderefs == 0 && !trait_in_other_version_found {
                             err.span_label(
@@ -3700,7 +3700,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // See if the `Type::function(val)` where `function` wasn't found corresponds to a
             // `Trait` that is imported directly, but `Type` came from a different version of the
             // same crate.
-            let rcvr_ty = self.tcx.type_of(def_id).instantiate_identity();
+
+            let rcvr_ty = match self.tcx.def_kind(def_id) {
+                DefKind::Struct | DefKind::Enum | DefKind::Union => {
+                    Some(self.tcx.type_of(def_id).instantiate_identity())
+                }
+                _ => None,
+            };
             trait_in_other_version_found = self.detect_and_explain_multiple_crate_versions(
                 err,
                 assoc.def_id,
@@ -4080,7 +4086,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         err: &mut Diag<'_>,
         item_def_id: DefId,
         hir_id: hir::HirId,
-        rcvr_ty: Ty<'_>,
+        rcvr_ty: Option<Ty<'_>>,
     ) -> bool {
         let hir_id = self.tcx.parent_hir_id(hir_id);
         let Some(traits) = self.tcx.in_scope_traits(hir_id) else { return false };
@@ -4110,8 +4116,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let mut multi_span: MultiSpan = trait_span.into();
         multi_span.push_span_label(trait_span, format!("this is the trait that is needed"));
         let descr = self.tcx.associated_item(item_def_id).descr();
+        let rcvr_ty =
+            rcvr_ty.map(|t| format!("`{t}`")).unwrap_or_else(|| "the receiver".to_string());
         multi_span
-            .push_span_label(item_span, format!("the {descr} is available for `{rcvr_ty}` here"));
+            .push_span_label(item_span, format!("the {descr} is available for {rcvr_ty} here"));
         for (def_id, import_def_id) in candidates {
             if let Some(import_def_id) = import_def_id {
                 multi_span.push_span_label(
diff --git a/tests/ui/methods/missing-method-on-type-parameter.rs b/tests/ui/methods/missing-method-on-type-parameter.rs
new file mode 100644
index 0000000000000..1471a72433a3a
--- /dev/null
+++ b/tests/ui/methods/missing-method-on-type-parameter.rs
@@ -0,0 +1,5 @@
+fn x<T: Copy>() {
+    T::try_from(); //~ ERROR E0599
+}
+
+fn main() {}
diff --git a/tests/ui/methods/missing-method-on-type-parameter.stderr b/tests/ui/methods/missing-method-on-type-parameter.stderr
new file mode 100644
index 0000000000000..9e255f9c0768b
--- /dev/null
+++ b/tests/ui/methods/missing-method-on-type-parameter.stderr
@@ -0,0 +1,19 @@
+error[E0599]: no function or associated item named `try_from` found for type parameter `T` in the current scope
+  --> $DIR/missing-method-on-type-parameter.rs:2:8
+   |
+LL | fn x<T: Copy>() {
+   |      - function or associated item `try_from` not found for this type parameter
+LL |     T::try_from();
+   |        ^^^^^^^^ function or associated item not found in `T`
+   |
+   = help: items from traits can only be used if the trait is in scope
+help: there is an associated function `from` with a similar name
+  --> $SRC_DIR/core/src/convert/mod.rs:LL:COL
+help: trait `TryFrom` which provides `try_from` is implemented but not in scope; perhaps you want to import it
+   |
+LL + use std::convert::TryFrom;
+   |
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0599`.