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Querify clashing_extern_declarations lint.

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This commit is contained in:
Camille GILLOT 2023-07-15 08:38:50 +00:00
parent ec5b882c2f
commit 817f45f7bf
6 changed files with 448 additions and 410 deletions
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3
compiler/rustc_interface/src/passes.rs
View file

@ -850,6 +850,9 @@ fn analysis(tcx: TyCtxt<'_>, (): ()) -> Result<()> {
rustc_lint::BuiltinCombinedLateLintPass::new() rustc_lint::BuiltinCombinedLateLintPass::new()
}); });
}); });
},
{
tcx.ensure().clashing_extern_declarations(());
} }
); );
}, },

393
compiler/rustc_lint/src/builtin.rs
View file

@ -24,10 +24,9 @@ use crate::fluent_generated as fluent;
use crate::{ use crate::{
errors::BuiltinEllipsisInclusiveRangePatterns, errors::BuiltinEllipsisInclusiveRangePatterns,
lints::{ lints::{
BuiltinAnonymousParams, BuiltinBoxPointers, BuiltinClashingExtern, BuiltinAnonymousParams, BuiltinBoxPointers, BuiltinConstNoMangle,
BuiltinClashingExternSub, BuiltinConstNoMangle, BuiltinDeprecatedAttrLink, BuiltinDeprecatedAttrLink, BuiltinDeprecatedAttrLinkSuggestion, BuiltinDeprecatedAttrUsed,
BuiltinDeprecatedAttrLinkSuggestion, BuiltinDeprecatedAttrUsed, BuiltinDerefNullptr, BuiltinDerefNullptr, BuiltinEllipsisInclusiveRangePatternsLint, BuiltinExplicitOutlives,
BuiltinEllipsisInclusiveRangePatternsLint, BuiltinExplicitOutlives,
BuiltinExplicitOutlivesSuggestion, BuiltinFeatureIssueNote, BuiltinIncompleteFeatures, BuiltinExplicitOutlivesSuggestion, BuiltinFeatureIssueNote, BuiltinIncompleteFeatures,
BuiltinIncompleteFeaturesHelp, BuiltinInternalFeatures, BuiltinKeywordIdents, BuiltinIncompleteFeaturesHelp, BuiltinInternalFeatures, BuiltinKeywordIdents,
BuiltinMissingCopyImpl, BuiltinMissingDebugImpl, BuiltinMissingDoc, BuiltinMissingCopyImpl, BuiltinMissingDebugImpl, BuiltinMissingDoc,
@ -40,7 +39,6 @@ use crate::{
BuiltinUnstableFeatures, BuiltinUnusedDocComment, BuiltinUnusedDocCommentSub, BuiltinUnstableFeatures, BuiltinUnusedDocComment, BuiltinUnusedDocCommentSub,
BuiltinWhileTrue, SuggestChangingAssocTypes, BuiltinWhileTrue, SuggestChangingAssocTypes,
}, },
types::{transparent_newtype_field, CItemKind},
EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext, EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext,
}; };
use hir::IsAsync; use hir::IsAsync;
@ -49,28 +47,26 @@ use rustc_ast::tokenstream::{TokenStream, TokenTree};
use rustc_ast::visit::{FnCtxt, FnKind}; use rustc_ast::visit::{FnCtxt, FnKind};
use rustc_ast::{self as ast, *}; use rustc_ast::{self as ast, *};
use rustc_ast_pretty::pprust::{self, expr_to_string}; use rustc_ast_pretty::pprust::{self, expr_to_string};
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::stack::ensure_sufficient_stack;
use rustc_errors::{Applicability, DecorateLint, MultiSpan}; use rustc_errors::{Applicability, DecorateLint, MultiSpan};
use rustc_feature::{deprecated_attributes, AttributeGate, BuiltinAttribute, GateIssue, Stability}; use rustc_feature::{deprecated_attributes, AttributeGate, BuiltinAttribute, GateIssue, Stability};
use rustc_hir as hir; use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res}; use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdSet, CRATE_DEF_ID}; use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdSet, CRATE_DEF_ID};
use rustc_hir::intravisit::FnKind as HirFnKind; use rustc_hir::intravisit::FnKind as HirFnKind;
use rustc_hir::{Body, FnDecl, ForeignItemKind, GenericParamKind, Node, PatKind, PredicateOrigin}; use rustc_hir::{Body, FnDecl, GenericParamKind, Node, PatKind, PredicateOrigin};
use rustc_middle::lint::in_external_macro; use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::layout::{LayoutError, LayoutOf}; use rustc_middle::ty::layout::LayoutOf;
use rustc_middle::ty::print::with_no_trimmed_paths; use rustc_middle::ty::print::with_no_trimmed_paths;
use rustc_middle::ty::GenericArgKind; use rustc_middle::ty::GenericArgKind;
use rustc_middle::ty::TypeVisitableExt; use rustc_middle::ty::TypeVisitableExt;
use rustc_middle::ty::{self, Instance, Ty, TyCtxt, VariantDef}; use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef};
use rustc_session::config::ExpectedValues; use rustc_session::config::ExpectedValues;
use rustc_session::lint::{BuiltinLintDiagnostics, FutureIncompatibilityReason}; use rustc_session::lint::{BuiltinLintDiagnostics, FutureIncompatibilityReason};
use rustc_span::edition::Edition; use rustc_span::edition::Edition;
use rustc_span::source_map::Spanned; use rustc_span::source_map::Spanned;
use rustc_span::symbol::{kw, sym, Ident, Symbol}; use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{BytePos, InnerSpan, Span}; use rustc_span::{BytePos, InnerSpan, Span};
use rustc_target::abi::{Abi, FIRST_VARIANT}; use rustc_target::abi::Abi;
use rustc_trait_selection::infer::{InferCtxtExt, TyCtxtInferExt}; use rustc_trait_selection::infer::{InferCtxtExt, TyCtxtInferExt};
use rustc_trait_selection::traits::{self, misc::type_allowed_to_implement_copy}; use rustc_trait_selection::traits::{self, misc::type_allowed_to_implement_copy};
@ -2612,381 +2608,6 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
} }
} }
declare_lint! {
/// The `clashing_extern_declarations` lint detects when an `extern fn`
/// has been declared with the same name but different types.
///
/// ### Example
///
/// ```rust
/// mod m {
/// extern "C" {
/// fn foo();
/// }
/// }
///
/// extern "C" {
/// fn foo(_: u32);
/// }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// Because two symbols of the same name cannot be resolved to two
/// different functions at link time, and one function cannot possibly
/// have two types, a clashing extern declaration is almost certainly a
/// mistake. Check to make sure that the `extern` definitions are correct
/// and equivalent, and possibly consider unifying them in one location.
///
/// This lint does not run between crates because a project may have
/// dependencies which both rely on the same extern function, but declare
/// it in a different (but valid) way. For example, they may both declare
/// an opaque type for one or more of the arguments (which would end up
/// distinct types), or use types that are valid conversions in the
/// language the `extern fn` is defined in. In these cases, the compiler
/// can't say that the clashing declaration is incorrect.
pub CLASHING_EXTERN_DECLARATIONS,
Warn,
"detects when an extern fn has been declared with the same name but different types"
}
pub struct ClashingExternDeclarations {
/// Map of function symbol name to the first-seen hir id for that symbol name.. If seen_decls
/// contains an entry for key K, it means a symbol with name K has been seen by this lint and
/// the symbol should be reported as a clashing declaration.
// FIXME: Technically, we could just store a &'tcx str here without issue; however, the
// `impl_lint_pass` macro doesn't currently support lints parametric over a lifetime.
seen_decls: FxHashMap<Symbol, hir::OwnerId>,
}
/// Differentiate between whether the name for an extern decl came from the link_name attribute or
/// just from declaration itself. This is important because we don't want to report clashes on
/// symbol name if they don't actually clash because one or the other links against a symbol with a
/// different name.
enum SymbolName {
/// The name of the symbol + the span of the annotation which introduced the link name.
Link(Symbol, Span),
/// No link name, so just the name of the symbol.
Normal(Symbol),
}
impl SymbolName {
fn get_name(&self) -> Symbol {
match self {
SymbolName::Link(s, _) | SymbolName::Normal(s) => *s,
}
}
}
impl ClashingExternDeclarations {
pub(crate) fn new() -> Self {
ClashingExternDeclarations { seen_decls: FxHashMap::default() }
}
/// Insert a new foreign item into the seen set. If a symbol with the same name already exists
/// for the item, return its HirId without updating the set.
fn insert(&mut self, tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> Option<hir::OwnerId> {
let did = fi.owner_id.to_def_id();
let instance = Instance::new(did, ty::List::identity_for_item(tcx, did));
let name = Symbol::intern(tcx.symbol_name(instance).name);
if let Some(&existing_id) = self.seen_decls.get(&name) {
// Avoid updating the map with the new entry when we do find a collision. We want to
// make sure we're always pointing to the first definition as the previous declaration.
// This lets us avoid emitting "knock-on" diagnostics.
Some(existing_id)
} else {
self.seen_decls.insert(name, fi.owner_id)
}
}
/// Get the name of the symbol that's linked against for a given extern declaration. That is,
/// the name specified in a #[link_name = ...] attribute if one was specified, else, just the
/// symbol's name.
fn name_of_extern_decl(tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> SymbolName {
if let Some((overridden_link_name, overridden_link_name_span)) =
tcx.codegen_fn_attrs(fi.owner_id).link_name.map(|overridden_link_name| {
// FIXME: Instead of searching through the attributes again to get span
// information, we could have codegen_fn_attrs also give span information back for
// where the attribute was defined. However, until this is found to be a
// bottleneck, this does just fine.
(overridden_link_name, tcx.get_attr(fi.owner_id, sym::link_name).unwrap().span)
})
{
SymbolName::Link(overridden_link_name, overridden_link_name_span)
} else {
SymbolName::Normal(fi.ident.name)
}
}
/// Checks whether two types are structurally the same enough that the declarations shouldn't
/// clash. We need this so we don't emit a lint when two modules both declare an extern struct,
/// with the same members (as the declarations shouldn't clash).
fn structurally_same_type<'tcx>(
cx: &LateContext<'tcx>,
a: Ty<'tcx>,
b: Ty<'tcx>,
ckind: CItemKind,
) -> bool {
fn structurally_same_type_impl<'tcx>(
seen_types: &mut FxHashSet<(Ty<'tcx>, Ty<'tcx>)>,
cx: &LateContext<'tcx>,
a: Ty<'tcx>,
b: Ty<'tcx>,
ckind: CItemKind,
) -> bool {
debug!("structurally_same_type_impl(cx, a = {:?}, b = {:?})", a, b);
let tcx = cx.tcx;
// Given a transparent newtype, reach through and grab the inner
// type unless the newtype makes the type non-null.
let non_transparent_ty = |mut ty: Ty<'tcx>| -> Ty<'tcx> {
loop {
if let ty::Adt(def, args) = *ty.kind() {
let is_transparent = def.repr().transparent();
let is_non_null = crate::types::nonnull_optimization_guaranteed(tcx, def);
debug!(
"non_transparent_ty({:?}) -- type is transparent? {}, type is non-null? {}",
ty, is_transparent, is_non_null
);
if is_transparent && !is_non_null {
debug_assert_eq!(def.variants().len(), 1);
let v = &def.variant(FIRST_VARIANT);
// continue with `ty`'s non-ZST field,
// otherwise `ty` is a ZST and we can return
if let Some(field) = transparent_newtype_field(tcx, v) {
ty = field.ty(tcx, args);
continue;
}
}
}
debug!("non_transparent_ty -> {:?}", ty);
return ty;
}
};
let a = non_transparent_ty(a);
let b = non_transparent_ty(b);
if !seen_types.insert((a, b)) {
// We've encountered a cycle. There's no point going any further -- the types are
// structurally the same.
true
} else if a == b {
// All nominally-same types are structurally same, too.
true
} else {
// Do a full, depth-first comparison between the two.
use rustc_type_ir::sty::TyKind::*;
let a_kind = a.kind();
let b_kind = b.kind();
let compare_layouts = |a, b| -> Result<bool, LayoutError<'tcx>> {
debug!("compare_layouts({:?}, {:?})", a, b);
let a_layout = &cx.layout_of(a)?.layout.abi();
let b_layout = &cx.layout_of(b)?.layout.abi();
debug!(
"comparing layouts: {:?} == {:?} = {}",
a_layout,
b_layout,
a_layout == b_layout
);
Ok(a_layout == b_layout)
};
#[allow(rustc::usage_of_ty_tykind)]
let is_primitive_or_pointer = |kind: &ty::TyKind<'_>| {
kind.is_primitive() || matches!(kind, RawPtr(..) | Ref(..))
};
ensure_sufficient_stack(|| {
match (a_kind, b_kind) {
(Adt(a_def, _), Adt(b_def, _)) => {
// We can immediately rule out these types as structurally same if
// their layouts differ.
match compare_layouts(a, b) {
Ok(false) => return false,
_ => (), // otherwise, continue onto the full, fields comparison
}
// Grab a flattened representation of all fields.
let a_fields = a_def.variants().iter().flat_map(|v| v.fields.iter());
let b_fields = b_def.variants().iter().flat_map(|v| v.fields.iter());
// Perform a structural comparison for each field.
a_fields.eq_by(
b_fields,
|&ty::FieldDef { did: a_did, .. },
&ty::FieldDef { did: b_did, .. }| {
structurally_same_type_impl(
seen_types,
cx,
tcx.type_of(a_did).instantiate_identity(),
tcx.type_of(b_did).instantiate_identity(),
ckind,
)
},
)
}
(Array(a_ty, a_const), Array(b_ty, b_const)) => {
// For arrays, we also check the constness of the type.
a_const.kind() == b_const.kind()
&& structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
}
(Slice(a_ty), Slice(b_ty)) => {
structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
}
(RawPtr(a_tymut), RawPtr(b_tymut)) => {
a_tymut.mutbl == b_tymut.mutbl
&& structurally_same_type_impl(
seen_types, cx, a_tymut.ty, b_tymut.ty, ckind,
)
}
(Ref(_a_region, a_ty, a_mut), Ref(_b_region, b_ty, b_mut)) => {
// For structural sameness, we don't need the region to be same.
a_mut == b_mut
&& structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind)
}
(FnDef(..), FnDef(..)) => {
let a_poly_sig = a.fn_sig(tcx);
let b_poly_sig = b.fn_sig(tcx);
// We don't compare regions, but leaving bound regions around ICEs, so
// we erase them.
let a_sig = tcx.erase_late_bound_regions(a_poly_sig);
let b_sig = tcx.erase_late_bound_regions(b_poly_sig);
(a_sig.abi, a_sig.unsafety, a_sig.c_variadic)
== (b_sig.abi, b_sig.unsafety, b_sig.c_variadic)
&& a_sig.inputs().iter().eq_by(b_sig.inputs().iter(), |a, b| {
structurally_same_type_impl(seen_types, cx, *a, *b, ckind)
})
&& structurally_same_type_impl(
seen_types,
cx,
a_sig.output(),
b_sig.output(),
ckind,
)
}
(Tuple(a_args), Tuple(b_args)) => {
a_args.iter().eq_by(b_args.iter(), |a_ty, b_ty| {
structurally_same_type_impl(seen_types, cx, a_ty, b_ty, ckind)
})
}
// For these, it's not quite as easy to define structural-sameness quite so easily.
// For the purposes of this lint, take the conservative approach and mark them as
// not structurally same.
(Dynamic(..), Dynamic(..))
| (Error(..), Error(..))
| (Closure(..), Closure(..))
| (Generator(..), Generator(..))
| (GeneratorWitness(..), GeneratorWitness(..))
| (Alias(ty::Projection, ..), Alias(ty::Projection, ..))
| (Alias(ty::Inherent, ..), Alias(ty::Inherent, ..))
| (Alias(ty::Opaque, ..), Alias(ty::Opaque, ..)) => false,
// These definitely should have been caught above.
(Bool, Bool) | (Char, Char) | (Never, Never) | (Str, Str) => unreachable!(),
// An Adt and a primitive or pointer type. This can be FFI-safe if non-null
// enum layout optimisation is being applied.
(Adt(..), other_kind) | (other_kind, Adt(..))
if is_primitive_or_pointer(other_kind) =>
{
let (primitive, adt) =
if is_primitive_or_pointer(a.kind()) { (a, b) } else { (b, a) };
if let Some(ty) = crate::types::repr_nullable_ptr(cx, adt, ckind) {
ty == primitive
} else {
compare_layouts(a, b).unwrap_or(false)
}
}
// Otherwise, just compare the layouts. This may fail to lint for some
// incompatible types, but at the very least, will stop reads into
// uninitialised memory.
_ => compare_layouts(a, b).unwrap_or(false),
}
})
}
}
let mut seen_types = FxHashSet::default();
structurally_same_type_impl(&mut seen_types, cx, a, b, ckind)
}
}
impl_lint_pass!(ClashingExternDeclarations => [CLASHING_EXTERN_DECLARATIONS]);
impl<'tcx> LateLintPass<'tcx> for ClashingExternDeclarations {
#[instrument(level = "trace", skip(self, cx))]
fn check_foreign_item(&mut self, cx: &LateContext<'tcx>, this_fi: &hir::ForeignItem<'_>) {
if let ForeignItemKind::Fn(..) = this_fi.kind {
let tcx = cx.tcx;
if let Some(existing_did) = self.insert(tcx, this_fi) {
let existing_decl_ty = tcx.type_of(existing_did).skip_binder();
let this_decl_ty = tcx.type_of(this_fi.owner_id).instantiate_identity();
debug!(
"ClashingExternDeclarations: Comparing existing {:?}: {:?} to this {:?}: {:?}",
existing_did, existing_decl_ty, this_fi.owner_id, this_decl_ty
);
// Check that the declarations match.
if !Self::structurally_same_type(
cx,
existing_decl_ty,
this_decl_ty,
CItemKind::Declaration,
) {
let orig_fi = tcx.hir().expect_foreign_item(existing_did);
let orig = Self::name_of_extern_decl(tcx, orig_fi);
// We want to ensure that we use spans for both decls that include where the
// name was defined, whether that was from the link_name attribute or not.
let get_relevant_span =
|fi: &hir::ForeignItem<'_>| match Self::name_of_extern_decl(tcx, fi) {
SymbolName::Normal(_) => fi.span,
SymbolName::Link(_, annot_span) => fi.span.to(annot_span),
};
// Finally, emit the diagnostic.
let this = this_fi.ident.name;
let orig = orig.get_name();
let previous_decl_label = get_relevant_span(orig_fi);
let mismatch_label = get_relevant_span(this_fi);
let sub = BuiltinClashingExternSub {
tcx,
expected: existing_decl_ty,
found: this_decl_ty,
};
let decorator = if orig == this {
BuiltinClashingExtern::SameName {
this,
orig,
previous_decl_label,
mismatch_label,
sub,
}
} else {
BuiltinClashingExtern::DiffName {
this,
orig,
previous_decl_label,
mismatch_label,
sub,
}
};
tcx.emit_spanned_lint(
CLASHING_EXTERN_DECLARATIONS,
this_fi.hir_id(),
get_relevant_span(this_fi),
decorator,
);
}
}
}
}
}
declare_lint! { declare_lint! {
/// The `deref_nullptr` lint detects when an null pointer is dereferenced, /// The `deref_nullptr` lint detects when an null pointer is dereferenced,
/// which causes [undefined behavior]. /// which causes [undefined behavior].

409
compiler/rustc_lint/src/foreign_modules.rs Normal file
View file

@ -0,0 +1,409 @@
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::stack::ensure_sufficient_stack;
use rustc_hir as hir;
use rustc_middle::query::Providers;
use rustc_middle::ty::layout::LayoutError;
use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
use rustc_session::lint::{lint_array, LintArray};
use rustc_span::{sym, Span, Symbol};
use rustc_target::abi::FIRST_VARIANT;
use crate::lints::{BuiltinClashingExtern, BuiltinClashingExternSub};
use crate::types;
pub(crate) fn provide(providers: &mut Providers) {
*providers = Providers { clashing_extern_declarations, ..*providers };
}
pub(crate) fn get_lints() -> LintArray {
lint_array!(CLASHING_EXTERN_DECLARATIONS)
}
fn clashing_extern_declarations(tcx: TyCtxt<'_>, (): ()) {
let mut lint = ClashingExternDeclarations::new();
for id in tcx.hir_crate_items(()).foreign_items() {
lint.check_foreign_item(tcx, tcx.hir().foreign_item(id));
}
}
declare_lint! {
/// The `clashing_extern_declarations` lint detects when an `extern fn`
/// has been declared with the same name but different types.
///
/// ### Example
///
/// ```rust
/// mod m {
/// extern "C" {
/// fn foo();
/// }
/// }
///
/// extern "C" {
/// fn foo(_: u32);
/// }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// Because two symbols of the same name cannot be resolved to two
/// different functions at link time, and one function cannot possibly
/// have two types, a clashing extern declaration is almost certainly a
/// mistake. Check to make sure that the `extern` definitions are correct
/// and equivalent, and possibly consider unifying them in one location.
///
/// This lint does not run between crates because a project may have
/// dependencies which both rely on the same extern function, but declare
/// it in a different (but valid) way. For example, they may both declare
/// an opaque type for one or more of the arguments (which would end up
/// distinct types), or use types that are valid conversions in the
/// language the `extern fn` is defined in. In these cases, the compiler
/// can't say that the clashing declaration is incorrect.
pub CLASHING_EXTERN_DECLARATIONS,
Warn,
"detects when an extern fn has been declared with the same name but different types"
}
struct ClashingExternDeclarations {
/// Map of function symbol name to the first-seen hir id for that symbol name.. If seen_decls
/// contains an entry for key K, it means a symbol with name K has been seen by this lint and
/// the symbol should be reported as a clashing declaration.
// FIXME: Technically, we could just store a &'tcx str here without issue; however, the
// `impl_lint_pass` macro doesn't currently support lints parametric over a lifetime.
seen_decls: FxHashMap<Symbol, hir::OwnerId>,
}
/// Differentiate between whether the name for an extern decl came from the link_name attribute or
/// just from declaration itself. This is important because we don't want to report clashes on
/// symbol name if they don't actually clash because one or the other links against a symbol with a
/// different name.
enum SymbolName {
/// The name of the symbol + the span of the annotation which introduced the link name.
Link(Symbol, Span),
/// No link name, so just the name of the symbol.
Normal(Symbol),
}
impl SymbolName {
fn get_name(&self) -> Symbol {
match self {
SymbolName::Link(s, _) | SymbolName::Normal(s) => *s,
}
}
}
impl ClashingExternDeclarations {
pub(crate) fn new() -> Self {
ClashingExternDeclarations { seen_decls: FxHashMap::default() }
}
/// Insert a new foreign item into the seen set. If a symbol with the same name already exists
/// for the item, return its HirId without updating the set.
fn insert(&mut self, tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> Option<hir::OwnerId> {
let did = fi.owner_id.to_def_id();
let instance = Instance::new(did, ty::List::identity_for_item(tcx, did));
let name = Symbol::intern(tcx.symbol_name(instance).name);
if let Some(&existing_id) = self.seen_decls.get(&name) {
// Avoid updating the map with the new entry when we do find a collision. We want to
// make sure we're always pointing to the first definition as the previous declaration.
// This lets us avoid emitting "knock-on" diagnostics.
Some(existing_id)
} else {
self.seen_decls.insert(name, fi.owner_id)
}
}
/// Get the name of the symbol that's linked against for a given extern declaration. That is,
/// the name specified in a #[link_name = ...] attribute if one was specified, else, just the
/// symbol's name.
fn name_of_extern_decl(tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> SymbolName {
if let Some((overridden_link_name, overridden_link_name_span)) =
tcx.codegen_fn_attrs(fi.owner_id).link_name.map(|overridden_link_name| {
// FIXME: Instead of searching through the attributes again to get span
// information, we could have codegen_fn_attrs also give span information back for
// where the attribute was defined. However, until this is found to be a
// bottleneck, this does just fine.
(overridden_link_name, tcx.get_attr(fi.owner_id, sym::link_name).unwrap().span)
})
{
SymbolName::Link(overridden_link_name, overridden_link_name_span)
} else {
SymbolName::Normal(fi.ident.name)
}
}
/// Checks whether two types are structurally the same enough that the declarations shouldn't
/// clash. We need this so we don't emit a lint when two modules both declare an extern struct,
/// with the same members (as the declarations shouldn't clash).
fn structurally_same_type<'tcx>(
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
a: Ty<'tcx>,
b: Ty<'tcx>,
ckind: types::CItemKind,
) -> bool {
fn structurally_same_type_impl<'tcx>(
seen_types: &mut FxHashSet<(Ty<'tcx>, Ty<'tcx>)>,
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
a: Ty<'tcx>,
b: Ty<'tcx>,
ckind: types::CItemKind,
) -> bool {
debug!("structurally_same_type_impl(tcx, a = {:?}, b = {:?})", a, b);
// Given a transparent newtype, reach through and grab the inner
// type unless the newtype makes the type non-null.
let non_transparent_ty = |mut ty: Ty<'tcx>| -> Ty<'tcx> {
loop {
if let ty::Adt(def, args) = *ty.kind() {
let is_transparent = def.repr().transparent();
let is_non_null = types::nonnull_optimization_guaranteed(tcx, def);
debug!(
"non_transparent_ty({:?}) -- type is transparent? {}, type is non-null? {}",
ty, is_transparent, is_non_null
);
if is_transparent && !is_non_null {
debug_assert_eq!(def.variants().len(), 1);
let v = &def.variant(FIRST_VARIANT);
// continue with `ty`'s non-ZST field,
// otherwise `ty` is a ZST and we can return
if let Some(field) = types::transparent_newtype_field(tcx, v) {
ty = field.ty(tcx, args);
continue;
}
}
}
debug!("non_transparent_ty -> {:?}", ty);
return ty;
}
};
let a = non_transparent_ty(a);
let b = non_transparent_ty(b);
if !seen_types.insert((a, b)) {
// We've encountered a cycle. There's no point going any further -- the types are
// structurally the same.
true
} else if a == b {
// All nominally-same types are structurally same, too.
true
} else {
// Do a full, depth-first comparison between the two.
use rustc_type_ir::sty::TyKind::*;
let a_kind = a.kind();
let b_kind = b.kind();
let compare_layouts = |a, b| -> Result<bool, &'tcx LayoutError<'tcx>> {
debug!("compare_layouts({:?}, {:?})", a, b);
let a_layout = &tcx.layout_of(param_env.and(a))?.layout.abi();
let b_layout = &tcx.layout_of(param_env.and(b))?.layout.abi();
debug!(
"comparing layouts: {:?} == {:?} = {}",
a_layout,
b_layout,
a_layout == b_layout
);
Ok(a_layout == b_layout)
};
#[allow(rustc::usage_of_ty_tykind)]
let is_primitive_or_pointer = |kind: &ty::TyKind<'_>| {
kind.is_primitive() || matches!(kind, RawPtr(..) | Ref(..))
};
ensure_sufficient_stack(|| {
match (a_kind, b_kind) {
(Adt(a_def, _), Adt(b_def, _)) => {
// We can immediately rule out these types as structurally same if
// their layouts differ.
match compare_layouts(a, b) {
Ok(false) => return false,
_ => (), // otherwise, continue onto the full, fields comparison
}
// Grab a flattened representation of all fields.
let a_fields = a_def.variants().iter().flat_map(|v| v.fields.iter());
let b_fields = b_def.variants().iter().flat_map(|v| v.fields.iter());
// Perform a structural comparison for each field.
a_fields.eq_by(
b_fields,
|&ty::FieldDef { did: a_did, .. },
&ty::FieldDef { did: b_did, .. }| {
structurally_same_type_impl(
seen_types,
tcx,
param_env,
tcx.type_of(a_did).instantiate_identity(),
tcx.type_of(b_did).instantiate_identity(),
ckind,
)
},
)
}
(Array(a_ty, a_const), Array(b_ty, b_const)) => {
// For arrays, we also check the constness of the type.
a_const.kind() == b_const.kind()
&& structurally_same_type_impl(
seen_types, tcx, param_env, *a_ty, *b_ty, ckind,
)
}
(Slice(a_ty), Slice(b_ty)) => structurally_same_type_impl(
seen_types, tcx, param_env, *a_ty, *b_ty, ckind,
),
(RawPtr(a_tymut), RawPtr(b_tymut)) => {
a_tymut.mutbl == b_tymut.mutbl
&& structurally_same_type_impl(
seen_types, tcx, param_env, a_tymut.ty, b_tymut.ty, ckind,
)
}
(Ref(_a_region, a_ty, a_mut), Ref(_b_region, b_ty, b_mut)) => {
// For structural sameness, we don't need the region to be same.
a_mut == b_mut
&& structurally_same_type_impl(
seen_types, tcx, param_env, *a_ty, *b_ty, ckind,
)
}
(FnDef(..), FnDef(..)) => {
let a_poly_sig = a.fn_sig(tcx);
let b_poly_sig = b.fn_sig(tcx);
// We don't compare regions, but leaving bound regions around ICEs, so
// we erase them.
let a_sig = tcx.erase_late_bound_regions(a_poly_sig);
let b_sig = tcx.erase_late_bound_regions(b_poly_sig);
(a_sig.abi, a_sig.unsafety, a_sig.c_variadic)
== (b_sig.abi, b_sig.unsafety, b_sig.c_variadic)
&& a_sig.inputs().iter().eq_by(b_sig.inputs().iter(), |a, b| {
structurally_same_type_impl(
seen_types, tcx, param_env, *a, *b, ckind,
)
})
&& structurally_same_type_impl(
seen_types,
tcx,
param_env,
a_sig.output(),
b_sig.output(),
ckind,
)
}
(Tuple(a_args), Tuple(b_args)) => {
a_args.iter().eq_by(b_args.iter(), |a_ty, b_ty| {
structurally_same_type_impl(
seen_types, tcx, param_env, a_ty, b_ty, ckind,
)
})
}
// For these, it's not quite as easy to define structural-sameness quite so easily.
// For the purposes of this lint, take the conservative approach and mark them as
// not structurally same.
(Dynamic(..), Dynamic(..))
| (Error(..), Error(..))
| (Closure(..), Closure(..))
| (Generator(..), Generator(..))
| (GeneratorWitness(..), GeneratorWitness(..))
| (Alias(ty::Projection, ..), Alias(ty::Projection, ..))
| (Alias(ty::Inherent, ..), Alias(ty::Inherent, ..))
| (Alias(ty::Opaque, ..), Alias(ty::Opaque, ..)) => false,
// These definitely should have been caught above.
(Bool, Bool) | (Char, Char) | (Never, Never) | (Str, Str) => unreachable!(),
// An Adt and a primitive or pointer type. This can be FFI-safe if non-null
// enum layout optimisation is being applied.
(Adt(..), other_kind) | (other_kind, Adt(..))
if is_primitive_or_pointer(other_kind) =>
{
let (primitive, adt) =
if is_primitive_or_pointer(a.kind()) { (a, b) } else { (b, a) };
if let Some(ty) = types::repr_nullable_ptr(tcx, param_env, adt, ckind) {
ty == primitive
} else {
compare_layouts(a, b).unwrap_or(false)
}
}
// Otherwise, just compare the layouts. This may fail to lint for some
// incompatible types, but at the very least, will stop reads into
// uninitialised memory.
_ => compare_layouts(a, b).unwrap_or(false),
}
})
}
}
let mut seen_types = FxHashSet::default();
structurally_same_type_impl(&mut seen_types, tcx, param_env, a, b, ckind)
}
#[instrument(level = "trace", skip(self, tcx))]
fn check_foreign_item<'tcx>(&mut self, tcx: TyCtxt<'tcx>, this_fi: &hir::ForeignItem<'_>) {
if let hir::ForeignItemKind::Fn(..) = this_fi.kind {
if let Some(existing_did) = self.insert(tcx, this_fi) {
let existing_decl_ty = tcx.type_of(existing_did).skip_binder();
let this_decl_ty = tcx.type_of(this_fi.owner_id).instantiate_identity();
debug!(
"ClashingExternDeclarations: Comparing existing {:?}: {:?} to this {:?}: {:?}",
existing_did, existing_decl_ty, this_fi.owner_id, this_decl_ty
);
// Check that the declarations match.
if !Self::structurally_same_type(
tcx,
tcx.param_env(this_fi.owner_id),
existing_decl_ty,
this_decl_ty,
types::CItemKind::Declaration,
) {
let orig_fi = tcx.hir().expect_foreign_item(existing_did);
let orig = Self::name_of_extern_decl(tcx, orig_fi);
// We want to ensure that we use spans for both decls that include where the
// name was defined, whether that was from the link_name attribute or not.
let get_relevant_span =
|fi: &hir::ForeignItem<'_>| match Self::name_of_extern_decl(tcx, fi) {
SymbolName::Normal(_) => fi.span,
SymbolName::Link(_, annot_span) => fi.span.to(annot_span),
};
// Finally, emit the diagnostic.
let this = this_fi.ident.name;
let orig = orig.get_name();
let previous_decl_label = get_relevant_span(orig_fi);
let mismatch_label = get_relevant_span(this_fi);
let sub = BuiltinClashingExternSub {
tcx,
expected: existing_decl_ty,
found: this_decl_ty,
};
let decorator = if orig == this {
BuiltinClashingExtern::SameName {
this,
orig,
previous_decl_label,
mismatch_label,
sub,
}
} else {
BuiltinClashingExtern::DiffName {
this,
orig,
previous_decl_label,
mismatch_label,
sub,
}
};
tcx.emit_spanned_lint(
CLASHING_EXTERN_DECLARATIONS,
this_fi.hir_id(),
get_relevant_span(this_fi),
decorator,
);
}
}
}
}
}

5
compiler/rustc_lint/src/lib.rs
View file

@ -59,6 +59,7 @@ mod enum_intrinsics_non_enums;
mod errors; mod errors;
mod expect; mod expect;
mod for_loops_over_fallibles; mod for_loops_over_fallibles;
mod foreign_modules;
pub mod hidden_unicode_codepoints; pub mod hidden_unicode_codepoints;
mod internal; mod internal;
mod invalid_from_utf8; mod invalid_from_utf8;
@ -140,6 +141,7 @@ fluent_messages! { "../messages.ftl" }
pub fn provide(providers: &mut Providers) { pub fn provide(providers: &mut Providers) {
levels::provide(providers); levels::provide(providers);
expect::provide(providers); expect::provide(providers);
foreign_modules::provide(providers);
*providers = Providers { lint_mod, ..*providers }; *providers = Providers { lint_mod, ..*providers };
} }
@ -195,8 +197,6 @@ late_lint_methods!(
// FIXME: Turn the computation of types which implement Debug into a query // FIXME: Turn the computation of types which implement Debug into a query
// and change this to a module lint pass // and change this to a module lint pass
MissingDebugImplementations: MissingDebugImplementations::default(), MissingDebugImplementations: MissingDebugImplementations::default(),
// Keeps a global list of foreign declarations.
ClashingExternDeclarations: ClashingExternDeclarations::new(),
] ]
] ]
); );
@ -282,6 +282,7 @@ fn register_builtins(store: &mut LintStore) {
store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints()); store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints()); store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
store.register_lints(&BuiltinCombinedLateLintPass::get_lints()); store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
store.register_lints(&foreign_modules::get_lints());
add_lint_group!( add_lint_group!(
"nonstandard_style", "nonstandard_style",

43
compiler/rustc_lint/src/types.rs
View file

@ -815,8 +815,7 @@ pub fn transparent_newtype_field<'a, 'tcx>(
} }
/// Is type known to be non-null? /// Is type known to be non-null?
fn ty_is_known_nonnull<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, mode: CItemKind) -> bool { fn ty_is_known_nonnull<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, mode: CItemKind) -> bool {
let tcx = cx.tcx;
match ty.kind() { match ty.kind() {
ty::FnPtr(_) => true, ty::FnPtr(_) => true,
ty::Ref(..) => true, ty::Ref(..) => true,
@ -835,8 +834,8 @@ fn ty_is_known_nonnull<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, mode: CItemKi
def.variants() def.variants()
.iter() .iter()
.filter_map(|variant| transparent_newtype_field(cx.tcx, variant)) .filter_map(|variant| transparent_newtype_field(tcx, variant))
.any(|field| ty_is_known_nonnull(cx, field.ty(tcx, args), mode)) .any(|field| ty_is_known_nonnull(tcx, field.ty(tcx, args), mode))
} }
_ => false, _ => false,
} }
@ -844,15 +843,12 @@ fn ty_is_known_nonnull<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, mode: CItemKi
/// Given a non-null scalar (or transparent) type `ty`, return the nullable version of that type. /// Given a non-null scalar (or transparent) type `ty`, return the nullable version of that type.
/// If the type passed in was not scalar, returns None. /// If the type passed in was not scalar, returns None.
fn get_nullable_type<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> { fn get_nullable_type<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
let tcx = cx.tcx;
Some(match *ty.kind() { Some(match *ty.kind() {
ty::Adt(field_def, field_args) => { ty::Adt(field_def, field_args) => {
let inner_field_ty = { let inner_field_ty = {
let mut first_non_zst_ty = field_def let mut first_non_zst_ty =
.variants() field_def.variants().iter().filter_map(|v| transparent_newtype_field(tcx, v));
.iter()
.filter_map(|v| transparent_newtype_field(cx.tcx, v));
debug_assert_eq!( debug_assert_eq!(
first_non_zst_ty.clone().count(), first_non_zst_ty.clone().count(),
1, 1,
@ -863,7 +859,7 @@ fn get_nullable_type<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'t
.expect("No non-zst fields in transparent type.") .expect("No non-zst fields in transparent type.")
.ty(tcx, field_args) .ty(tcx, field_args)
}; };
return get_nullable_type(cx, inner_field_ty); return get_nullable_type(tcx, inner_field_ty);
} }
ty::Int(ty) => Ty::new_int(tcx, ty), ty::Int(ty) => Ty::new_int(tcx, ty),
ty::Uint(ty) => Ty::new_uint(tcx, ty), ty::Uint(ty) => Ty::new_uint(tcx, ty),
@ -895,43 +891,44 @@ fn get_nullable_type<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'t
/// `core::ptr::NonNull`, and `#[repr(transparent)]` newtypes. /// `core::ptr::NonNull`, and `#[repr(transparent)]` newtypes.
/// FIXME: This duplicates code in codegen. /// FIXME: This duplicates code in codegen.
pub(crate) fn repr_nullable_ptr<'tcx>( pub(crate) fn repr_nullable_ptr<'tcx>(
cx: &LateContext<'tcx>, tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
ty: Ty<'tcx>, ty: Ty<'tcx>,
ckind: CItemKind, ckind: CItemKind,
) -> Option<Ty<'tcx>> { ) -> Option<Ty<'tcx>> {
debug!("is_repr_nullable_ptr(cx, ty = {:?})", ty); debug!("is_repr_nullable_ptr(tcx, ty = {:?})", ty);
if let ty::Adt(ty_def, args) = ty.kind() { if let ty::Adt(ty_def, args) = ty.kind() {
let field_ty = match &ty_def.variants().raw[..] { let field_ty = match &ty_def.variants().raw[..] {
[var_one, var_two] => match (&var_one.fields.raw[..], &var_two.fields.raw[..]) { [var_one, var_two] => match (&var_one.fields.raw[..], &var_two.fields.raw[..]) {
([], [field]) | ([field], []) => field.ty(cx.tcx, args), ([], [field]) | ([field], []) => field.ty(tcx, args),
_ => return None, _ => return None,
}, },
_ => return None, _ => return None,
}; };
if !ty_is_known_nonnull(cx, field_ty, ckind) { if !ty_is_known_nonnull(tcx, field_ty, ckind) {
return None; return None;
} }
// At this point, the field's type is known to be nonnull and the parent enum is Option-like. // At this point, the field's type is known to be nonnull and the parent enum is Option-like.
// If the computed size for the field and the enum are different, the nonnull optimization isn't // If the computed size for the field and the enum are different, the nonnull optimization isn't
// being applied (and we've got a problem somewhere). // being applied (and we've got a problem somewhere).
let compute_size_skeleton = |t| SizeSkeleton::compute(t, cx.tcx, cx.param_env).unwrap(); let compute_size_skeleton = |t| SizeSkeleton::compute(t, tcx, param_env).unwrap();
if !compute_size_skeleton(ty).same_size(compute_size_skeleton(field_ty)) { if !compute_size_skeleton(ty).same_size(compute_size_skeleton(field_ty)) {
bug!("improper_ctypes: Option nonnull optimization not applied?"); bug!("improper_ctypes: Option nonnull optimization not applied?");
} }
// Return the nullable type this Option-like enum can be safely represented with. // Return the nullable type this Option-like enum can be safely represented with.
let field_ty_abi = &cx.layout_of(field_ty).unwrap().abi; let field_ty_abi = &tcx.layout_of(param_env.and(field_ty)).unwrap().abi;
if let Abi::Scalar(field_ty_scalar) = field_ty_abi { if let Abi::Scalar(field_ty_scalar) = field_ty_abi {
match field_ty_scalar.valid_range(cx) { match field_ty_scalar.valid_range(&tcx) {
WrappingRange { start: 0, end } WrappingRange { start: 0, end }
if end == field_ty_scalar.size(&cx.tcx).unsigned_int_max() - 1 => if end == field_ty_scalar.size(&tcx).unsigned_int_max() - 1 =>
{ {
return Some(get_nullable_type(cx, field_ty).unwrap()); return Some(get_nullable_type(tcx, field_ty).unwrap());
} }
WrappingRange { start: 1, .. } => { WrappingRange { start: 1, .. } => {
return Some(get_nullable_type(cx, field_ty).unwrap()); return Some(get_nullable_type(tcx, field_ty).unwrap());
} }
WrappingRange { start, end } => { WrappingRange { start, end } => {
unreachable!("Unhandled start and end range: ({}, {})", start, end) unreachable!("Unhandled start and end range: ({}, {})", start, end)
@ -1116,7 +1113,9 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
if !def.repr().c() && !def.repr().transparent() && def.repr().int.is_none() if !def.repr().c() && !def.repr().transparent() && def.repr().int.is_none()
{ {
// Special-case types like `Option<extern fn()>`. // Special-case types like `Option<extern fn()>`.
if repr_nullable_ptr(self.cx, ty, self.mode).is_none() { if repr_nullable_ptr(self.cx.tcx, self.cx.param_env, ty, self.mode)
.is_none()
{
return FfiUnsafe { return FfiUnsafe {
ty, ty,
reason: fluent::lint_improper_ctypes_enum_repr_reason, reason: fluent::lint_improper_ctypes_enum_repr_reason,

5
compiler/rustc_middle/src/query/mod.rs
View file

@ -1596,6 +1596,11 @@ rustc_queries! {
separate_provide_extern separate_provide_extern
} }
/// Lint against `extern fn` declarations having incompatible types.
query clashing_extern_declarations(_: ()) {
desc { "checking `extern fn` declarations are compatible" }
}
/// Identifies the entry-point (e.g., the `main` function) for a given /// Identifies the entry-point (e.g., the `main` function) for a given
/// crate, returning `None` if there is no entry point (such as for library crates). /// crate, returning `None` if there is no entry point (such as for library crates).
query entry_fn(_: ()) -> Option<(DefId, EntryFnType)> { query entry_fn(_: ()) -> Option<(DefId, EntryFnType)> {