Auto merge of #84562 - richkadel:issue-83601, r=tmandry
Adds feature-gated `#[no_coverage]` function attribute, to fix derived Eq `0` coverage issue #83601 Derived Eq no longer shows uncovered The Eq trait has a special hidden function. MIR `InstrumentCoverage` would add this function to the coverage map, but it is never called, so the `Eq` trait would always appear uncovered. Fixes: #83601 The fix required creating a new function attribute `no_coverage` to mark functions that should be ignored by `InstrumentCoverage` and the coverage `mapgen` (during codegen). Adding a `no_coverage` feature gate with tracking issue #84605. r? `@tmandry` cc: `@wesleywiser`
This commit is contained in:
commit
20040fa332
18 changed files with 198 additions and 2 deletions
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@ -16,9 +16,19 @@ pub fn expand_deriving_eq(
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push: &mut dyn FnMut(Annotatable),
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) {
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let inline = cx.meta_word(span, sym::inline);
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let no_coverage_ident =
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rustc_ast::attr::mk_nested_word_item(Ident::new(sym::no_coverage, span));
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let no_coverage_feature =
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rustc_ast::attr::mk_list_item(Ident::new(sym::feature, span), vec![no_coverage_ident]);
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let no_coverage = cx.meta_word(span, sym::no_coverage);
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let hidden = rustc_ast::attr::mk_nested_word_item(Ident::new(sym::hidden, span));
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let doc = rustc_ast::attr::mk_list_item(Ident::new(sym::doc, span), vec![hidden]);
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let attrs = vec![cx.attribute(inline), cx.attribute(doc)];
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let attrs = vec![
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cx.attribute(inline),
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cx.attribute(no_coverage_feature),
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cx.attribute(no_coverage),
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cx.attribute(doc),
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];
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let trait_def = TraitDef {
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span,
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attributes: Vec::new(),
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@ -8,6 +8,7 @@ use rustc_codegen_ssa::traits::{ConstMethods, CoverageInfoMethods};
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use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
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use rustc_hir::def_id::{DefId, DefIdSet, LOCAL_CRATE};
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use rustc_llvm::RustString;
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use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
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use rustc_middle::mir::coverage::CodeRegion;
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use rustc_span::Symbol;
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@ -280,6 +281,10 @@ fn add_unused_functions<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>) {
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let mut unused_def_ids_by_file: FxHashMap<Symbol, Vec<DefId>> = FxHashMap::default();
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for &non_codegenned_def_id in all_def_ids.difference(codegenned_def_ids) {
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let codegen_fn_attrs = tcx.codegen_fn_attrs(non_codegenned_def_id);
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if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_COVERAGE) {
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continue;
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}
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// Make sure the non-codegenned (unused) function has a file_name
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if let Some(non_codegenned_file_name) = tcx.covered_file_name(non_codegenned_def_id) {
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let def_ids =
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@ -646,6 +646,10 @@ declare_features! (
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/// Allows `extern "wasm" fn`
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(active, wasm_abi, "1.53.0", Some(83788), None),
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/// Allows function attribute `#[no_coverage]`, to bypass coverage
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/// instrumentation of that function.
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(active, no_coverage, "1.53.0", Some(84605), None),
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/// Allows trait bounds in `const fn`.
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(active, const_fn_trait_bound, "1.53.0", Some(57563), None),
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@ -273,6 +273,13 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
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template!(List: "address, memory, thread"),
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experimental!(no_sanitize)
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),
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ungated!(
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// Not exclusively gated at the crate level (though crate-level is
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// supported). The feature can alternatively be enabled on individual
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// functions.
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no_coverage, AssumedUsed,
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template!(Word),
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),
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// FIXME: #14408 assume docs are used since rustdoc looks at them.
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ungated!(doc, AssumedUsed, template!(List: "hidden|inline|...", NameValueStr: "string")),
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@ -89,6 +89,10 @@ bitflags! {
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/// #[cmse_nonsecure_entry]: with a TrustZone-M extension, declare a
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/// function as an entry function from Non-Secure code.
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const CMSE_NONSECURE_ENTRY = 1 << 14;
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/// `#[no_coverage]`: indicates that the function should be ignored by
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/// the MIR `InstrumentCoverage` pass and not added to the coverage map
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/// during codegen.
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const NO_COVERAGE = 1 << 15;
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}
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}
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@ -23,6 +23,7 @@ use rustc_index::vec::IndexVec;
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use rustc_middle::hir;
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use rustc_middle::hir::map::blocks::FnLikeNode;
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use rustc_middle::ich::StableHashingContext;
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use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
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use rustc_middle::mir::coverage::*;
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use rustc_middle::mir::{
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self, BasicBlock, BasicBlockData, Coverage, SourceInfo, Statement, StatementKind, Terminator,
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@ -87,6 +88,11 @@ impl<'tcx> MirPass<'tcx> for InstrumentCoverage {
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_ => {}
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}
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let codegen_fn_attrs = tcx.codegen_fn_attrs(mir_source.def_id());
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if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_COVERAGE) {
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return;
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}
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trace!("InstrumentCoverage starting for {:?}", mir_source.def_id());
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Instrumentor::new(&self.name(), tcx, mir_body).inject_counters();
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trace!("InstrumentCoverage starting for {:?}", mir_source.def_id());
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@ -781,6 +781,7 @@ symbols! {
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no,
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no_builtins,
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no_core,
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no_coverage,
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no_crate_inject,
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no_debug,
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no_default_passes,
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@ -2661,6 +2661,8 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
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let mut inline_span = None;
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let mut link_ordinal_span = None;
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let mut no_sanitize_span = None;
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let mut no_coverage_feature_enabled = false;
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let mut no_coverage_attr = None;
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for attr in attrs.iter() {
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if tcx.sess.check_name(attr, sym::cold) {
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codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
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@ -2724,6 +2726,15 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
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codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
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} else if tcx.sess.check_name(attr, sym::no_mangle) {
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codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
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} else if attr.has_name(sym::feature) {
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if let Some(list) = attr.meta_item_list() {
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if list.iter().any(|nested_meta_item| nested_meta_item.has_name(sym::no_coverage)) {
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tcx.sess.mark_attr_used(attr);
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no_coverage_feature_enabled = true;
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}
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}
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} else if tcx.sess.check_name(attr, sym::no_coverage) {
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no_coverage_attr = Some(attr);
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} else if tcx.sess.check_name(attr, sym::rustc_std_internal_symbol) {
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codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
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} else if tcx.sess.check_name(attr, sym::used) {
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@ -2934,6 +2945,23 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
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}
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}
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if let Some(no_coverage_attr) = no_coverage_attr {
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if tcx.sess.features_untracked().no_coverage || no_coverage_feature_enabled {
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codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE
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} else {
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let mut err = feature_err(
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&tcx.sess.parse_sess,
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sym::no_coverage,
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no_coverage_attr.span,
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"the `#[no_coverage]` attribute is an experimental feature",
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);
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if tcx.sess.parse_sess.unstable_features.is_nightly_build() {
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err.help("or, alternatively, add `#[feature(no_coverage)]` to the function");
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}
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err.emit();
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}
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}
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codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
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if !attr.has_name(sym::inline) {
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return ia;
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