Auto merge of #71445 - Dylan-DPC:rollup-31givp1, r=Dylan-DPC

Rollup of 5 pull requests

Successful merges:

 - #71256 (Lint must_use on mem::replace)
 - #71350 (Error code explanation extra check)
 - #71369 (allow wasm32 compilation of librustc_data_structures/profiling.rs)
 - #71400 (proc_macro::is_available())
 - #71440 (Implement `Copy` for `AllocErr`)

Failed merges:

r? @ghost

4 files changed, 33 insertions, 1 deletions

diff --git a/src/test/ui/imports/import-in-block.rs b/src/test/ui/imports/import-in-block.rs
index c0ba6220b54..19703904ece 100644
--- a/src/test/ui/imports/import-in-block.rs
+++ b/src/test/ui/imports/import-in-block.rs
@@ -4,7 +4,7 @@
 pub fn main() {
     use std::mem::replace;
     let mut x = 5;
-    replace(&mut x, 6);
+    let _ = replace(&mut x, 6);
     {
         use std::mem::*;
         let mut y = 6;
diff --git a/src/test/ui/issues/issue-23611-enum-swap-in-drop.rs b/src/test/ui/issues/issue-23611-enum-swap-in-drop.rs
index 6ef7fd42ec6..403cf970bcb 100644
--- a/src/test/ui/issues/issue-23611-enum-swap-in-drop.rs
+++ b/src/test/ui/issues/issue-23611-enum-swap-in-drop.rs
@@ -153,6 +153,7 @@ impl<'a> Drop for E<'a> {
             }
         };
 
+        #[allow(unused_must_use)]
         if do_drop {
             mem::replace(self, E::A(GaspA(f_a, 0xA3A0, log, D::new("drop", 6, log)), true));
         }
diff --git a/src/test/ui/proc-macro/auxiliary/is-available.rs b/src/test/ui/proc-macro/auxiliary/is-available.rs
new file mode 100644
index 00000000000..0caf186db1d
--- /dev/null
+++ b/src/test/ui/proc-macro/auxiliary/is-available.rs
@@ -0,0 +1,14 @@
+// force-host
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+#![feature(proc_macro_is_available)]
+
+extern crate proc_macro;
+
+use proc_macro::{Literal, TokenStream, TokenTree};
+
+#[proc_macro]
+pub fn from_inside_proc_macro(_input: TokenStream) -> TokenStream {
+    proc_macro::is_available().to_string().parse().unwrap()
+}
diff --git a/src/test/ui/proc-macro/is-available.rs b/src/test/ui/proc-macro/is-available.rs
new file mode 100644
index 00000000000..943d9fe797a
--- /dev/null
+++ b/src/test/ui/proc-macro/is-available.rs
@@ -0,0 +1,17 @@
+// run-pass
+
+#![feature(proc_macro_hygiene, proc_macro_is_available)]
+
+extern crate proc_macro;
+
+// aux-build:is-available.rs
+extern crate is_available;
+
+fn main() {
+    let a = proc_macro::is_available();
+    let b = is_available::from_inside_proc_macro!();
+    let c = proc_macro::is_available();
+    assert!(!a);
+    assert!(b);
+    assert!(!c);
+}