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authorbors <bors@rust-lang.org>2025-02-19 04:37:26 +0000
committerbors <bors@rust-lang.org>2025-02-19 04:37:26 +0000
commit5986ff05d8480da038dd161b3a6aa79ff364a851 (patch)
tree1a1274cb0be9cf42d367279eef79156f5ebe2678 /compiler/rustc_error_codes/src
parent17c1c329a5512d718b67ef6797538b154016cd34 (diff)
parent24ba1ad31ceb5537bb03bedfb6aac888b7b313b9 (diff)
downloadrust-5986ff05d8480da038dd161b3a6aa79ff364a851.tar.gz
rust-5986ff05d8480da038dd161b3a6aa79ff364a851.zip
Auto merge of #137248 - matthiaskrgr:rollup-s18zjau, r=matthiaskrgr
Rollup of 9 pull requests

Successful merges:

 - #136936 (Use 'yes' instead of 'while-echo' in tests/ui/process/process-sigpipe.rs except 'nto')
 - #137026 (Stabilize (and const-stabilize) `integer_sign_cast`)
 - #137059 (fix: Alloc new errorcode E0803 for E0495)
 - #137177 (Update `minifier-rs` version to `0.3.5`)
 - #137210 (compiler: Stop reexporting stuff in cg_llvm::abi)
 - #137213 (Remove `rustc_middle::mir::tcx` module.)
 - #137216 (eval_outlives: bail out early if both regions are in the same SCC)
 - #137228 (Fix typo in hidden internal docs of `TrustedRandomAccess`)
 - #137242 (Add reference annotations for the `do_not_recommend` attribute)

r? `@ghost`
`@rustbot` modify labels: rollup
Diffstat (limited to 'compiler/rustc_error_codes/src')
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0803.md46
-rw-r--r--compiler/rustc_error_codes/src/lib.rs1
2 files changed, 47 insertions, 0 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0803.md b/compiler/rustc_error_codes/src/error_codes/E0803.md
new file mode 100644
index 00000000000..4c022688a2d
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0803.md
@@ -0,0 +1,46 @@
+A trait implementation returns a reference without an
+explicit lifetime linking it to `self`.
+It commonly arises in generic trait implementations
+requiring explicit lifetime bounds.
+
+Erroneous code example:
+
+```compile_fail,E0803
+trait DataAccess<T> {
+    fn get_ref(&self) -> T;
+}
+
+struct Container<'a> {
+    value: &'a f64,
+}
+
+// Attempting to implement reference return
+impl<'a> DataAccess<&f64> for Container<'a> {
+    fn get_ref(&self) -> &f64 { // Error: Lifetime mismatch
+        self.value
+    }
+}
+```
+
+The trait method returns &f64 requiring an independent lifetime
+The struct Container<'a> carries lifetime parameter 'a
+The compiler cannot verify if the returned reference satisfies 'a constraints
+Solution
+Explicitly bind lifetimes to clarify constraints:
+```
+// Modified trait with explicit lifetime binding
+trait DataAccess<'a, T> {
+    fn get_ref(&'a self) -> T;
+}
+
+struct Container<'a> {
+    value: &'a f64,
+}
+
+// Correct implementation (bound lifetimes)
+impl<'a> DataAccess<'a, &'a f64> for Container<'a> {
+    fn get_ref(&'a self) -> &'a f64 {
+        self.value
+    }
+}
+```
diff --git a/compiler/rustc_error_codes/src/lib.rs b/compiler/rustc_error_codes/src/lib.rs
index e970b16f610..098ca42be2b 100644
--- a/compiler/rustc_error_codes/src/lib.rs
+++ b/compiler/rustc_error_codes/src/lib.rs
@@ -546,6 +546,7 @@ E0799: 0799,
 E0800: 0800,
 E0801: 0801,
 E0802: 0802,
+E0803: 0803,
         );
     )
 }