From 9213cb80c29941a7fb752413613c2c68f7e7d7b3 Mon Sep 17 00:00:00 2001
From: Folkert de Vries <folkert@folkertdev.nl>
Date: Sun, 9 Mar 2025 16:47:38 +0100
Subject: [PATCH] fix ICE in pretty-printing `global_asm!`

---
 compiler/rustc_middle/src/mir/pretty.rs                  | 5 ++++-
 tests/mir-opt/global_asm.rs                              | 9 +++++++++
 ...bal_asm.{global_asm#0}.SimplifyLocals-final.after.mir | 9 +++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 tests/mir-opt/global_asm.rs
 create mode 100644 tests/mir-opt/global_asm.{global_asm#0}.SimplifyLocals-final.after.mir

diff --git a/compiler/rustc_middle/src/mir/pretty.rs b/compiler/rustc_middle/src/mir/pretty.rs
index f880b1364c2cd..05da8511361cd 100644
--- a/compiler/rustc_middle/src/mir/pretty.rs
+++ b/compiler/rustc_middle/src/mir/pretty.rs
@@ -653,7 +653,10 @@ fn write_mir_sig(tcx: TyCtxt<'_>, body: &Body<'_>, w: &mut dyn io::Write) -> io:
             write!(w, "static mut ")?
         }
         (_, _) if is_function => write!(w, "fn ")?,
-        (DefKind::AnonConst | DefKind::InlineConst, _) => {} // things like anon const, not an item
+        // things like anon const, not an item
+        (DefKind::AnonConst | DefKind::InlineConst, _) => {}
+        // `global_asm!` have fake bodies, which we may dump after mir-build
+        (DefKind::GlobalAsm, _) => {}
         _ => bug!("Unexpected def kind {:?}", kind),
     }
 
diff --git a/tests/mir-opt/global_asm.rs b/tests/mir-opt/global_asm.rs
new file mode 100644
index 0000000000000..22b782d365e94
--- /dev/null
+++ b/tests/mir-opt/global_asm.rs
@@ -0,0 +1,9 @@
+// skip-filecheck
+//@ needs-asm-support
+
+// `global_asm!` gets a fake body, make sure it is handled correctly
+
+// EMIT_MIR global_asm.{global_asm#0}.SimplifyLocals-final.after.mir
+core::arch::global_asm!("/* */");
+
+fn main() {}
diff --git a/tests/mir-opt/global_asm.{global_asm#0}.SimplifyLocals-final.after.mir b/tests/mir-opt/global_asm.{global_asm#0}.SimplifyLocals-final.after.mir
new file mode 100644
index 0000000000000..cec3c4a8261e6
--- /dev/null
+++ b/tests/mir-opt/global_asm.{global_asm#0}.SimplifyLocals-final.after.mir
@@ -0,0 +1,9 @@
+// MIR for `{global_asm#0}` after SimplifyLocals-final
+
+{global_asm#0}: ! = {
+    let mut _0: !;
+
+    bb0: {
+        asm!("/* */", options()) -> unwind unreachable;
+    }
+}