Exempt #[naked] fns from named_asm_labels lint

Author: asquared31415

compiler/rustc_ast/src/ast.rs

@@ -2028,6 +2028,7 @@ pub enum InlineAsmOperand {
 #[derive(Clone, Encodable, Decodable, Debug)]
 pub struct InlineAsm {
     pub template: Vec<InlineAsmTemplatePiece>,
+    pub template_strs: Box<[(Symbol, Option<Symbol>, Span)]>,
     pub operands: Vec<(InlineAsmOperand, Span)>,
     pub clobber_abi: Option<(Symbol, Span)>,
     pub options: InlineAsmOptions,

compiler/rustc_ast/src/visit.rs

@@ -19,20 +19,20 @@ use crate::token;
 use rustc_span::symbol::{Ident, Symbol};
 use rustc_span::Span;
 
-#[derive(Copy, Clone, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq)]
 pub enum AssocCtxt {
     Trait,
     Impl,
 }
 
-#[derive(Copy, Clone, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq)]
 pub enum FnCtxt {
     Free,
     Foreign,
     Assoc(AssocCtxt),
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, Debug)]
 pub enum FnKind<'a> {
     /// E.g., `fn foo()`, `fn foo(&self)`, or `extern "Abi" fn foo()`.
     Fn(FnCtxt, Ident, &'a FnSig, &'a Visibility, Option<&'a Block>),

compiler/rustc_ast_lowering/src/asm.rs

@@ -392,8 +392,10 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
         let operands = self.arena.alloc_from_iter(operands);
         let template = self.arena.alloc_from_iter(asm.template.iter().cloned());
+        let template_strs = self.arena.alloc_from_iter(asm.template_strs.iter().cloned());
         let line_spans = self.arena.alloc_slice(&asm.line_spans[..]);
-        let hir_asm = hir::InlineAsm { template, operands, options: asm.options, line_spans };
+        let hir_asm =
+            hir::InlineAsm { template, template_strs, operands, options: asm.options, line_spans };
         self.arena.alloc(hir_asm)
     }
 }

compiler/rustc_builtin_macros/src/asm.rs

@@ -7,10 +7,10 @@ use rustc_errors::{Applicability, DiagnosticBuilder};
 use rustc_expand::base::{self, *};
 use rustc_parse::parser::Parser;
 use rustc_parse_format as parse;
-use rustc_session::lint::{self, BuiltinLintDiagnostics};
+use rustc_session::lint;
 use rustc_span::symbol::Ident;
 use rustc_span::symbol::{kw, sym, Symbol};
-use rustc_span::{InnerSpan, MultiSpan, Span};
+use rustc_span::{InnerSpan, Span};
 use rustc_target::asm::InlineAsmArch;
 use smallvec::smallvec;
 
@@ -484,11 +484,7 @@ fn parse_reg<'a>(
     Ok(result)
 }
 
-fn expand_preparsed_asm(
-    ecx: &mut ExtCtxt<'_>,
-    args: AsmArgs,
-    is_local_asm: bool,
-) -> Option<ast::InlineAsm> {
+fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::InlineAsm> {
     let mut template = vec![];
     // Register operands are implicitly used since they are not allowed to be
     // referenced in the template string.
@@ -501,6 +497,8 @@ fn expand_preparsed_asm(
     let mut line_spans = Vec::with_capacity(args.templates.len());
     let mut curarg = 0;
 
+    let mut template_strs = Vec::with_capacity(args.templates.len());
+
     for template_expr in args.templates.into_iter() {
         if !template.is_empty() {
             template.push(ast::InlineAsmTemplatePiece::String("\n".to_string()));
@@ -524,8 +522,13 @@ fn expand_preparsed_asm(
             ast::StrStyle::Raw(raw) => Some(raw as usize),
         };
 
-        let template_str = &template_str.as_str();
         let template_snippet = ecx.source_map().span_to_snippet(template_sp).ok();
+        template_strs.push((
+            template_str,
+            template_snippet.as_ref().map(|s| Symbol::intern(s)),
+            template_sp,
+        ));
+        let template_str = &template_str.as_str();
 
         if let Some(InlineAsmArch::X86 | InlineAsmArch::X86_64) = ecx.sess.asm_arch {
             let find_span = |needle: &str| -> Span {
@@ -560,72 +563,6 @@ fn expand_preparsed_asm(
             }
         }
 
-        // Lint against the use of named labels in inline `asm!` but not `global_asm!`
-        if is_local_asm {
-            let find_label_span = |needle: &str| -> Option<Span> {
-                if let Some(snippet) = &template_snippet {
-                    if let Some(pos) = snippet.find(needle) {
-                        let end = pos
-                            + &snippet[pos..]
-                                .find(|c| c == ':')
-                                .unwrap_or(snippet[pos..].len() - 1);
-                        let inner = InnerSpan::new(pos, end);
-                        return Some(template_sp.from_inner(inner));
-                    }
-                }
-
-                None
-            };
-
-            let mut found_labels = Vec::new();
-
-            // A semicolon might not actually be specified as a separator for all targets, but it seems like LLVM accepts it always
-            let statements = template_str.split(|c| matches!(c, '\n' | ';'));
-            for statement in statements {
-                // If there's a comment, trim it from the statement
-                let statement = statement.find("//").map_or(statement, |idx| &statement[..idx]);
-                let mut start_idx = 0;
-                for (idx, _) in statement.match_indices(':') {
-                    let possible_label = statement[start_idx..idx].trim();
-                    let mut chars = possible_label.chars();
-                    if let Some(c) = chars.next() {
-                        // A label starts with an alphabetic character or . or _ and continues with alphanumeric characters, _, or $
-                        if (c.is_alphabetic() || matches!(c, '.' | '_'))
-                            && chars.all(|c| c.is_alphanumeric() || matches!(c, '_' | '$'))
-                        {
-                            found_labels.push(possible_label);
-                        } else {
-                            // If we encounter a non-label, there cannot be any further labels, so stop checking
-                            break;
-                        }
-                    } else {
-                        // Empty string means a leading ':' in this section, which is not a label
-                        break;
-                    }
-
-                    start_idx = idx + 1;
-                }
-            }
-
-            if found_labels.len() > 0 {
-                let spans =
-                    found_labels.into_iter().filter_map(find_label_span).collect::<Vec<Span>>();
-                // If there were labels but we couldn't find a span, combine the warnings and use the template span
-                let target_spans: MultiSpan =
-                    if spans.len() > 0 { spans.into() } else { template_sp.into() };
-                ecx.parse_sess().buffer_lint_with_diagnostic(
-                    lint::builtin::NAMED_ASM_LABELS,
-                    target_spans,
-                    ecx.current_expansion.lint_node_id,
-                    "avoid using named labels in inline assembly",
-                    BuiltinLintDiagnostics::NamedAsmLabel(
-                        "only local labels of the form `<number>:` should be used in inline asm"
-                            .to_string(),
-                    ),
-                );
-            }
-        }
-
         // Don't treat raw asm as a format string.
         if args.options.contains(ast::InlineAsmOptions::RAW) {
             template.push(ast::InlineAsmTemplatePiece::String(template_str.to_string()));
@@ -819,6 +756,7 @@ fn expand_preparsed_asm(
 
     Some(ast::InlineAsm {
         template,
+        template_strs: template_strs.into_boxed_slice(),
         operands: args.operands,
         clobber_abi: args.clobber_abi,
         options: args.options,
@@ -833,7 +771,7 @@ pub fn expand_asm<'cx>(
 ) -> Box<dyn base::MacResult + 'cx> {
     match parse_args(ecx, sp, tts, false) {
         Ok(args) => {
-            let expr = if let Some(inline_asm) = expand_preparsed_asm(ecx, args, true) {
+            let expr = if let Some(inline_asm) = expand_preparsed_asm(ecx, args) {
                 P(ast::Expr {
                     id: ast::DUMMY_NODE_ID,
                     kind: ast::ExprKind::InlineAsm(P(inline_asm)),
@@ -860,7 +798,7 @@ pub fn expand_global_asm<'cx>(
 ) -> Box<dyn base::MacResult + 'cx> {
     match parse_args(ecx, sp, tts, true) {
         Ok(args) => {
-            if let Some(inline_asm) = expand_preparsed_asm(ecx, args, false) {
+            if let Some(inline_asm) = expand_preparsed_asm(ecx, args) {
                 MacEager::items(smallvec![P(ast::Item {
                     ident: Ident::invalid(),
                     attrs: Vec::new(),

compiler/rustc_hir/src/hir.rs

@@ -2386,6 +2386,7 @@ impl<'hir> InlineAsmOperand<'hir> {
 #[derive(Debug, HashStable_Generic)]
 pub struct InlineAsm<'hir> {
     pub template: &'hir [InlineAsmTemplatePiece],
+    pub template_strs: &'hir [(Symbol, Option<Symbol>, Span)],
     pub operands: &'hir [(InlineAsmOperand<'hir>, Span)],
     pub options: InlineAsmOptions,
     pub line_spans: &'hir [Span],

compiler/rustc_lint/src/builtin.rs

@@ -45,11 +45,11 @@ use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::subst::{GenericArgKind, Subst};
 use rustc_middle::ty::Instance;
 use rustc_middle::ty::{self, layout::LayoutError, Ty, TyCtxt};
-use rustc_session::lint::FutureIncompatibilityReason;
+use rustc_session::lint::{BuiltinLintDiagnostics, FutureIncompatibilityReason};
 use rustc_session::Session;
-use rustc_span::edition::Edition;
-use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
+use rustc_span::{edition::Edition, InnerSpan};
+use rustc_span::{source_map::Spanned, MultiSpan};
 use rustc_span::{BytePos, Span};
 use rustc_target::abi::{LayoutOf, VariantIdx};
 use rustc_trait_selection::traits::misc::can_type_implement_copy;
@@ -3140,3 +3140,134 @@ impl<'tcx> LateLintPass<'tcx> for DerefNullPtr {
         }
     }
 }
+
+declare_lint! {
+    /// The `named_asm_labels` lint detects the use of named labels in the
+    /// inline `asm!` macro.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![feature(asm)]
+    /// fn main() {
+    ///     unsafe {
+    ///         asm!("foo: bar");
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// LLVM is allowed to duplicate inline assembly blocks for any
+    /// reason, for example when it is in a function that gets inlined. Because
+    /// of this, GNU assembler [local labels] *must* be used instead of labels
+    /// with a name. Using named labels might cause assembler or linker errors.
+    ///
+    /// See the [unstable book] for more details.
+    ///
+    /// [local labels]: https://sourceware.org/binutils/docs/as/Symbol-Names.html#Local-Labels
+    /// [unstable book]: https://doc.rust-lang.org/nightly/unstable-book/library-features/asm.html#labels
+    pub NAMED_ASM_LABELS,
+    Deny,
+    "named labels in inline assembly",
+}
+
+declare_lint_pass!(NamedAsmLabels => [NAMED_ASM_LABELS]);
+
+impl<'tcx> LateLintPass<'tcx> for NamedAsmLabels {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
+        if let hir::Expr {
+            kind: hir::ExprKind::InlineAsm(hir::InlineAsm { template_strs, .. }),
+            ..
+        } = expr
+        {
+            let hir = cx.tcx.hir();
+            if let Some(enclosing_body) = cx.enclosing_body {
+                let fn_id = hir.get_parent_item(enclosing_body.hir_id);
+                let attrs = hir.attrs(fn_id);
+                // Process lint only if the containing fn does not have a `#[naked]` attribute
+                if attrs.iter().any(|attr| attr.has_name(sym::naked)) {
+                    return;
+                }
+
+                for (template_sym, template_snippet, template_span) in template_strs.iter() {
+                    let template_str = &template_sym.as_str();
+                    let find_label_span = |needle: &str| -> Option<Span> {
+                        if let Some(snippet) = template_snippet {
+                            let snippet = snippet.as_str();
+                            if let Some(pos) = snippet.find(needle) {
+                                let end = pos
+                                    + &snippet[pos..]
+                                        .find(|c| c == ':')
+                                        .unwrap_or(snippet[pos..].len() - 1);
+                                let inner = InnerSpan::new(pos, end);
+                                return Some(template_span.from_inner(inner));
+                            }
+                        }
+
+                        None
+                    };
+
+                    let mut found_labels = Vec::new();
+
+                    // A semicolon might not actually be specified as a separator for all targets, but it seems like LLVM accepts it always
+                    let statements = template_str.split(|c| matches!(c, '\n' | ';'));
+                    for statement in statements {
+                        // If there's a comment, trim it from the statement
+                        let statement =
+                            statement.find("//").map_or(statement, |idx| &statement[..idx]);
+                        let mut start_idx = 0;
+                        for (idx, _) in statement.match_indices(':') {
+                            let possible_label = statement[start_idx..idx].trim();
+                            let mut chars = possible_label.chars();
+                            if let Some(c) = chars.next() {
+                                // A label starts with an alphabetic character or . or _ and continues with alphanumeric characters, _, or $
+                                if (c.is_alphabetic() || matches!(c, '.' | '_'))
+                                    && chars.all(|c| c.is_alphanumeric() || matches!(c, '_' | '$'))
+                                {
+                                    found_labels.push(possible_label);
+                                } else {
+                                    // If we encounter a non-label, there cannot be any further labels, so stop checking
+                                    break;
+                                }
+                            } else {
+                                // Empty string means a leading ':' in this section, which is not a label
+                                break;
+                            }
+
+                            start_idx = idx + 1;
+                        }
+                    }
+
+                    debug!("NamedAsmLabels::check_expr(): found_labels: {:#?}", &found_labels);
+
+                    if found_labels.len() > 0 {
+                        let spans = found_labels
+                            .into_iter()
+                            .filter_map(|label| find_label_span(label))
+                            .collect::<Vec<Span>>();
+                        // If there were labels but we couldn't find a span, combine the warnings and use the template span
+                        let target_spans: MultiSpan =
+                            if spans.len() > 0 { spans.into() } else { (*template_span).into() };
+
+                        cx.lookup_with_diagnostics(
+                            NAMED_ASM_LABELS,
+                            Some(target_spans),
+                            |diag| {
+                                let mut err =
+                                    diag.build("avoid using named labels in inline assembly");
+                                err.emit();
+                            },
+                            BuiltinLintDiagnostics::NamedAsmLabel(
+                                "only local labels of the form `<number>:` should be used in inline asm"
+                                    .to_string(),
+                            ),
+                        );
+                    }
+                }
+            }
+        }
+    }
+}

compiler/rustc_lint/src/lib.rs

@@ -171,6 +171,7 @@ macro_rules! late_lint_passes {
                 NonPanicFmt: NonPanicFmt,
                 NoopMethodCall: NoopMethodCall,
                 InvalidAtomicOrdering: InvalidAtomicOrdering,
+                NamedAsmLabels: NamedAsmLabels,
             ]
         );
     };