Rollup merge of #127935 - tgross35:binary_asm_labels-x86-only, r=estebank

Change `binary_asm_labels` to only fire on x86 and x86_64

In <#126922>, the `binary_asm_labels` lint was added which flags labels such as `0:` and `1:`. Before that change, LLVM was giving a confusing error on x86/x86_64 because of an incorrect interpretation.

However, targets other than x86 and x86_64 never had the error message and have not been a problem. This means that the lint was causing code that previously worked to start failing (e.g. `compiler_builtins`), rather than only providing a more clear messages where there has always been an error.

Adjust the lint to only fire on x86 and x86_64 assembly to avoid this regression.

Also update the help message.

Fixes: #127821

Author: GuillaumeGomez

compiler/rustc_lint/messages.ftl

@@ -403,8 +403,9 @@ lint_inner_macro_attribute_unstable = inner macro attributes are unstable
 
 lint_invalid_asm_label_binary = avoid using labels containing only the digits `0` and `1` in inline assembly
     .label = use a different label that doesn't start with `0` or `1`
-    .note = an LLVM bug makes these labels ambiguous with a binary literal number
-    .note = see <https://bugs.llvm.org/show_bug.cgi?id=36144> for more information
+    .help = start numbering with `2` instead
+    .note1 = an LLVM bug makes these labels ambiguous with a binary literal number on x86
+    .note2 = see <https://github.com/llvm/llvm-project/issues/99547> for more information
 
 lint_invalid_asm_label_format_arg = avoid using named labels in inline assembly
     .help = only local labels of the form `<number>:` should be used in inline asm

compiler/rustc_lint/src/builtin.rs

@@ -66,6 +66,7 @@ use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{BytePos, InnerSpan, Span};
 use rustc_target::abi::Abi;
+use rustc_target::asm::InlineAsmArch;
 use rustc_trait_selection::infer::{InferCtxtExt, TyCtxtInferExt};
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc_trait_selection::traits::{self, misc::type_allowed_to_implement_copy};
@@ -2908,16 +2909,22 @@ impl<'tcx> LateLintPass<'tcx> for AsmLabels {
                                 InvalidAsmLabel::FormatArg { missing_precise_span },
                             );
                         }
-                        AsmLabelKind::Binary => {
-                            // the binary asm issue only occurs when using intel syntax
-                            if !options.contains(InlineAsmOptions::ATT_SYNTAX) {
-                                cx.emit_span_lint(
-                                    BINARY_ASM_LABELS,
-                                    span,
-                                    InvalidAsmLabel::Binary { missing_precise_span, span },
-                                )
-                            }
+                        // the binary asm issue only occurs when using intel syntax on x86 targets
+                        AsmLabelKind::Binary
+                            if !options.contains(InlineAsmOptions::ATT_SYNTAX)
+                                && matches!(
+                                    cx.tcx.sess.asm_arch,
+                                    Some(InlineAsmArch::X86 | InlineAsmArch::X86_64) | None
+                                ) =>
+                        {
+                            cx.emit_span_lint(
+                                BINARY_ASM_LABELS,
+                                span,
+                                InvalidAsmLabel::Binary { missing_precise_span, span },
+                            )
                         }
+                        // No lint on anything other than x86
+                        AsmLabelKind::Binary => (),
                     };
                 }
             }

compiler/rustc_lint/src/lints.rs

@@ -2074,7 +2074,9 @@ pub enum InvalidAsmLabel {
         missing_precise_span: bool,
     },
     #[diag(lint_invalid_asm_label_binary)]
-    #[note]
+    #[help]
+    #[note(lint_note1)]
+    #[note(lint_note2)]
     Binary {
         #[note(lint_invalid_asm_label_no_span)]
         missing_precise_span: bool,

tests/ui/asm/binary_asm_labels.stderr

@@ -4,7 +4,9 @@ error: avoid using labels containing only the digits `0` and `1` in inline assem
 LL |         asm!("0: jmp 0b");
    |               ^ use a different label that doesn't start with `0` or `1`
    |
-   = note: an LLVM bug makes these labels ambiguous with a binary literal number
+   = help: start numbering with `2` instead
+   = note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
+   = note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
    = note: `#[deny(binary_asm_labels)]` on by default
 
 error: avoid using labels containing only the digits `0` and `1` in inline assembly
@@ -13,31 +15,39 @@ error: avoid using labels containing only the digits `0` and `1` in inline assem
 LL |         asm!("1: jmp 1b");
    |               ^ use a different label that doesn't start with `0` or `1`
    |
-   = note: an LLVM bug makes these labels ambiguous with a binary literal number
+   = help: start numbering with `2` instead
+   = note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
+   = note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
 
 error: avoid using labels containing only the digits `0` and `1` in inline assembly
   --> $DIR/binary_asm_labels.rs:13:15
    |
 LL |         asm!("10: jmp 10b");
    |               ^^ use a different label that doesn't start with `0` or `1`
    |
-   = note: an LLVM bug makes these labels ambiguous with a binary literal number
+   = help: start numbering with `2` instead
+   = note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
+   = note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
 
 error: avoid using labels containing only the digits `0` and `1` in inline assembly
   --> $DIR/binary_asm_labels.rs:14:15
    |
 LL |         asm!("01: jmp 01b");
    |               ^^ use a different label that doesn't start with `0` or `1`
    |
-   = note: an LLVM bug makes these labels ambiguous with a binary literal number
+   = help: start numbering with `2` instead
+   = note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
+   = note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
 
 error: avoid using labels containing only the digits `0` and `1` in inline assembly
   --> $DIR/binary_asm_labels.rs:15:15
    |
 LL |         asm!("1001101: jmp 1001101b");
    |               ^^^^^^^ use a different label that doesn't start with `0` or `1`
    |
-   = note: an LLVM bug makes these labels ambiguous with a binary literal number
+   = help: start numbering with `2` instead
+   = note: an LLVM bug makes these labels ambiguous with a binary literal number on x86
+   = note: see <https://github.com/llvm/llvm-project/issues/99547> for more information
 
 error: aborting due to 5 previous errors
 

tests/ui/asm/binary_asm_labels_allowed.rs

@@ -0,0 +1,17 @@
+//@ build-pass
+//@ only-aarch64
+
+// The `binary_asm_labels` lint should only be raised on `x86`. Make sure it
+// doesn't get raised on other platforms.
+
+use std::arch::asm;
+
+fn main() {
+    unsafe {
+        asm!("0: bl 0b");
+        asm!("1: bl 1b");
+        asm!("10: bl 10b");
+        asm!("01: bl 01b");
+        asm!("1001101: bl 1001101b");
+    }
+}