various fixes for naked_asm! implementation

- fix for divergence
- fix error message
- fix another cranelift test
- fix some cranelift things
- don't set the NORETURN option for naked asm
- fix use of naked_asm! in doc comment
- fix use of naked_asm! in run-make test
- use `span_bug` in unreachable branch

compiler/rustc_ast/src/ast.rs

@@ -2435,7 +2435,7 @@ pub enum AsmMacro {
 }
 
 impl AsmMacro {
-    pub const fn macro_name(&self) -> &'static str {
+    pub const fn macro_name(self) -> &'static str {
         match self {
             AsmMacro::Asm => "asm",
             AsmMacro::GlobalAsm => "global_asm",
@@ -2443,13 +2443,21 @@ impl AsmMacro {
         }
     }
 
-    pub const fn is_supported_option(&self, option: InlineAsmOptions) -> bool {
+    pub const fn is_supported_option(self, option: InlineAsmOptions) -> bool {
         match self {
             AsmMacro::Asm => true,
             AsmMacro::GlobalAsm => InlineAsmOptions::GLOBAL_OPTIONS.contains(option),
             AsmMacro::NakedAsm => InlineAsmOptions::NAKED_OPTIONS.contains(option),
         }
     }
+
+    pub const fn diverges(self, options: InlineAsmOptions) -> bool {
+        match self {
+            AsmMacro::Asm => options.contains(InlineAsmOptions::NORETURN),
+            AsmMacro::GlobalAsm => true,
+            AsmMacro::NakedAsm => true,
+        }
+    }
 }
 
 /// Inline assembly.