Auto merge of #76231 - tmandry:rollup-ilvs9fq, r=tmandry

Rollup of 14 pull requests

Successful merges:

 - #74880 (Add trailing comma support to matches macro)
 - #76074 (Add new `-Z dump-mir-spanview` option)
 - #76088 (Add more examples to lexicographic cmp on Iterators.)
 - #76099 (Add info about `!` and `impl Trait`)
 - #76126 (Use "Fira Sans" for crate list font)
 - #76132 (Factor out StmtKind::MacCall fields into `MacCallStmt` struct)
 - #76143 (Give a better error message for duplicate built-in macros)
 - #76158 (Stabilise link-self-contained option)
 - #76201 (Move to intra-doc links for library/core/src/panic.rs)
 - #76206 (Make all methods of `std::net::Ipv6Addr` const)
 - #76207 (# Move to intra-doc links for library/core/src/clone.rs)
 - #76212 (Document lint missing_doc_code_examples is nightly-only)
 - #76218 (lexer: Tiny improvement to shebang detection)
 - #76221 (Clean up header in `iter` docs for `for` loops)

Failed merges:

r? @ghost

2 files changed, 39 insertions, 0 deletions

diff --git a/compiler/rustc_error_codes/src/error_codes.rs b/compiler/rustc_error_codes/src/error_codes.rs
index 4e5e77f80c2..789a1fc35a6 100644
--- a/compiler/rustc_error_codes/src/error_codes.rs
+++ b/compiler/rustc_error_codes/src/error_codes.rs
@@ -454,6 +454,7 @@ E0768: include_str!("./error_codes/E0768.md"),
 E0769: include_str!("./error_codes/E0769.md"),
 E0770: include_str!("./error_codes/E0770.md"),
 E0771: include_str!("./error_codes/E0771.md"),
+E0773: include_str!("./error_codes/E0773.md"),
 ;
 //  E0006, // merged with E0005
 //  E0008, // cannot bind by-move into a pattern guard
diff --git a/compiler/rustc_error_codes/src/error_codes/E0773.md b/compiler/rustc_error_codes/src/error_codes/E0773.md
new file mode 100644
index 00000000000..b19a58bf33d
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0773.md
@@ -0,0 +1,38 @@
+A builtin-macro was defined more than once.
+
+Erroneous code example:
+
+```compile_fail,E0773
+#![feature(decl_macro)]
+#![feature(rustc_attrs)]
+
+#[rustc_builtin_macro]
+pub macro test($item:item) {
+    /* compiler built-in */
+}
+
+mod inner {
+    #[rustc_builtin_macro]
+    pub macro test($item:item) {
+        /* compiler built-in */
+    }
+}
+```
+
+To fix the issue, remove the duplicate declaration:
+
+```
+#![feature(decl_macro)]
+#![feature(rustc_attrs)]
+
+#[rustc_builtin_macro]
+pub macro test($item:item) {
+    /* compiler built-in */
+}
+```
+
+In very rare edge cases, this may happen when loading `core` or `std` twice,
+once with `check` metadata and once with `build` metadata.
+For more information, see [#75176].
+
+[#75176]: https://github.com/rust-lang/rust/pull/75176#issuecomment-683234468