fix ICE in pretty-printing global_asm!

Author: folkertdev

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),
     }
 

tests/ui/unpretty/mir/global-asm.rs

@@ -0,0 +1,7 @@
+//@ compile-flags: -Zdump-mir=all --crate-type=lib
+//@ needs-asm-support
+//@ check-pass
+
+// `global_asm!` gets a fake body, make sure it is handled correctly
+
+std::arch::global_asm!("/* */");