Rollup merge of #128138 - folkertdev:asm-option-allowlist, r=lcnr

`#[naked]`: use an allowlist for allowed options on `asm!` in naked functions

tracking issue: https://github.com/rust-lang/rust/issues/90957

this is mostly just a refactor, but using an allowlist (rather than a denylist) for which asm options are allowed in naked functions is a little safer.

These options are disallowed because naked functions are effectively global asm, but defined using inline asm.

compiler/rustc_ast/src/ast.rs

@@ -2264,6 +2264,42 @@ bitflags::bitflags! {
     }
 }
 
+impl InlineAsmOptions {
+    pub fn human_readable_names(&self) -> Vec<&'static str> {
+        let mut options = vec![];
+
+        if self.contains(InlineAsmOptions::PURE) {
+            options.push("pure");
+        }
+        if self.contains(InlineAsmOptions::NOMEM) {
+            options.push("nomem");
+        }
+        if self.contains(InlineAsmOptions::READONLY) {
+            options.push("readonly");
+        }
+        if self.contains(InlineAsmOptions::PRESERVES_FLAGS) {
+            options.push("preserves_flags");
+        }
+        if self.contains(InlineAsmOptions::NORETURN) {
+            options.push("noreturn");
+        }
+        if self.contains(InlineAsmOptions::NOSTACK) {
+            options.push("nostack");
+        }
+        if self.contains(InlineAsmOptions::ATT_SYNTAX) {
+            options.push("att_syntax");
+        }
+        if self.contains(InlineAsmOptions::RAW) {
+            options.push("raw");
+        }
+        if self.contains(InlineAsmOptions::MAY_UNWIND) {
+            options.push("may_unwind");
+        }
+
+        options
+    }
+}
+
 impl std::fmt::Debug for InlineAsmOptions {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         bitflags::parser::to_writer(self, f)

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1505,35 +1505,7 @@ impl<'a> State<'a> {
             AsmArg::Options(opts) => {
                 s.word("options");
                 s.popen();
-                let mut options = vec![];
+                s.commasep(Inconsistent, &opts.human_readable_names(), |s, &opt| {
-                if opts.contains(InlineAsmOptions::PURE) {
-                    options.push("pure");
-                }
-                if opts.contains(InlineAsmOptions::NOMEM) {
-                    options.push("nomem");
-                }
-                if opts.contains(InlineAsmOptions::READONLY) {
-                    options.push("readonly");
-                }
-                if opts.contains(InlineAsmOptions::PRESERVES_FLAGS) {
-                    options.push("preserves_flags");
-                }
-                if opts.contains(InlineAsmOptions::NORETURN) {
-                    options.push("noreturn");
-                }
-                if opts.contains(InlineAsmOptions::NOSTACK) {
-                    options.push("nostack");
-                }
-                if opts.contains(InlineAsmOptions::ATT_SYNTAX) {
-                    options.push("att_syntax");
-                }
-                if opts.contains(InlineAsmOptions::RAW) {
-                    options.push("raw");
-                }
-                if opts.contains(InlineAsmOptions::MAY_UNWIND) {
-                    options.push("may_unwind");
-                }
-                s.commasep(Inconsistent, &options, |s, &opt| {
                     s.word(opt);
                 });
                 s.pclose();

compiler/rustc_hir_pretty/src/lib.rs

@@ -1298,35 +1298,7 @@ impl<'a> State<'a> {
             AsmArg::Options(opts) => {
                 s.word("options");
                 s.popen();
-                let mut options = vec![];
+                s.commasep(Inconsistent, &opts.human_readable_names(), |s, &opt| {
-                if opts.contains(ast::InlineAsmOptions::PURE) {
-                    options.push("pure");
-                }
-                if opts.contains(ast::InlineAsmOptions::NOMEM) {
-                    options.push("nomem");
-                }
-                if opts.contains(ast::InlineAsmOptions::READONLY) {
-                    options.push("readonly");
-                }
-                if opts.contains(ast::InlineAsmOptions::PRESERVES_FLAGS) {
-                    options.push("preserves_flags");
-                }
-                if opts.contains(ast::InlineAsmOptions::NORETURN) {
-                    options.push("noreturn");
-                }
-                if opts.contains(ast::InlineAsmOptions::NOSTACK) {
-                    options.push("nostack");
-                }
-                if opts.contains(ast::InlineAsmOptions::ATT_SYNTAX) {
-                    options.push("att_syntax");
-                }
-                if opts.contains(ast::InlineAsmOptions::RAW) {
-                    options.push("raw");
-                }
-                if opts.contains(ast::InlineAsmOptions::MAY_UNWIND) {
-                    options.push("may_unwind");
-                }
-                s.commasep(Inconsistent, &options, |s, &opt| {
                     s.word(opt);
                 });
                 s.pclose();

compiler/rustc_passes/src/naked_functions.rs

@@ -244,22 +244,19 @@ impl<'tcx> CheckInlineAssembly<'tcx> {
             self.tcx.dcx().emit_err(NakedFunctionsOperands { unsupported_operands });
         }
 
-        let unsupported_options: Vec<&'static str> = [
+        let supported_options =
-            (InlineAsmOptions::MAY_UNWIND, "`may_unwind`"),
+            InlineAsmOptions::RAW | InlineAsmOptions::NORETURN | InlineAsmOptions::ATT_SYNTAX;
-            (InlineAsmOptions::NOMEM, "`nomem`"),
+        let unsupported_options = asm.options.difference(supported_options);
-            (InlineAsmOptions::NOSTACK, "`nostack`"),
-            (InlineAsmOptions::PRESERVES_FLAGS, "`preserves_flags`"),
-            (InlineAsmOptions::PURE, "`pure`"),
-            (InlineAsmOptions::READONLY, "`readonly`"),
-        ]
-        .iter()
-        .filter_map(|&(option, name)| if asm.options.contains(option) { Some(name) } else { None })
-        .collect();
 
         if !unsupported_options.is_empty() {
             self.tcx.dcx().emit_err(NakedFunctionsAsmOptions {
                 span,
-                unsupported_options: unsupported_options.join(", "),
+                unsupported_options: unsupported_options
+                    .human_readable_names()
+                    .into_iter()
+                    .map(|name| format!("`{name}`"))
+                    .collect::<Vec<_>>()
+                    .join(", "),
             });
         }
 

tests/ui/asm/naked-functions.rs

@@ -111,7 +111,7 @@ unsafe extern "C" fn invalid_options() {
 unsafe extern "C" fn invalid_options_continued() {
     asm!("", options(readonly, nostack), options(pure));
     //~^ ERROR asm with the `pure` option must have at least one output
-    //~| ERROR asm options unsupported in naked functions: `nostack`, `pure`, `readonly`
+    //~| ERROR asm options unsupported in naked functions: `pure`, `readonly`, `nostack`
     //~| ERROR asm in naked functions must use `noreturn` option
 }
 

tests/ui/asm/naked-functions.stderr

@@ -212,7 +212,7 @@ error[E0787]: asm options unsupported in naked functions: `nomem`, `preserves_fl
 LL |     asm!("", options(nomem, preserves_flags, noreturn));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0787]: asm options unsupported in naked functions: `nostack`, `pure`, `readonly`
+error[E0787]: asm options unsupported in naked functions: `pure`, `readonly`, `nostack`
   --> $DIR/naked-functions.rs:112:5
    |
 LL |     asm!("", options(readonly, nostack), options(pure));