Files
swift-mirror/include/swift/AST/DeclNameLoc.h
Daniil Kovalev 971e696b96 [AST] Fix UB appearing due to strict aliasing rule violation (#85286)
This fixes the following tests which are now crashing due to hitting
unreachable "no buffer containing location found" in
`SourceManager::findBufferContainingLoc`:

- attr/attr_dynamic_member_lookup.swift
- AutoDiff/Sema/DerivativeRegistrationCrossModule/main.swift
- Constraints/construction.swift
- Constraints/members.swift
- NameLookup/accessibility.swift
- Sema/call_as_function_simple.swift

The root cause of the crash is as follows. All the tests involve
emitting `InaccessibleMemberFailure` error diagnostic (see
`InaccessibleMemberFailure::diagnoseAsError`). When `DeclNameLoc
nameLoc` is initialized via default constructor and is not re-assigned
with smth meaningful later, the check `nameLoc.isValid()` returns `true`
even though it should be `false`. It turns out that we treat `const void
*LocationInfo` as `SourceLoc` and hope that if `LocationInfo` is
`nullptr`, casting this to `SourceLoc` would produce a "default"
`SourceLoc` with `Pointer` member set to `nullptr`. But such a cast (see
`getSourceLocs()` member of `DeclNameLoc`) is undefined behavior. So,
the compiler assumes that `Pointer` member of `SourceLoc` we try to cast
to is not `nullptr` (due to strict aliasing rule), which leads to
`nameLoc.isValid()` being mistakenly computed as `true`.

This patch resolves the issue by handling this special case separately.
2025-11-04 07:53:30 +00:00

163 lines
5.2 KiB
C++

//===--- DeclNameLoc.h - Declaration Name Location Info ---------*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file defines the DeclNameLoc class.
//
//===----------------------------------------------------------------------===//
#ifndef SWIFT_AST_DECL_NAME_LOC_H
#define SWIFT_AST_DECL_NAME_LOC_H
#include "swift/Basic/LLVM.h"
#include "swift/Basic/SourceLoc.h"
#include "llvm/ADT/ArrayRef.h"
class BridgedDeclNameLoc;
namespace swift {
class ASTContext;
/// Source location information for a declaration name (\c DeclName)
/// written in the source.
class DeclNameLoc {
friend class ::BridgedDeclNameLoc;
/// Source location information.
///
/// If \c NumArgumentLabels == 0 and \c !HasModuleSelectorLoc, this is the
/// SourceLoc for the base name. Otherwise, it points to an array of
/// SourceLocs, which contains:
/// * The base name location
/// * The module selector location
/// * The left parentheses location
/// * The right parentheses location
/// * The locations of each of the argument labels.
const void *LocationInfo;
/// The number of argument labels stored in the name.
uint32_t NumArgumentLabels;
bool HasModuleSelectorLoc;
enum {
BaseNameIndex = 0,
ModuleSelectorIndex = 1,
LParenIndex = 2,
RParenIndex = 3,
FirstArgumentLabelIndex = 4,
};
/// Retrieve a pointer to either the only source location that was
/// stored or to the array of source locations that was stored.
SourceLoc const * getSourceLocs() const {
if (NumArgumentLabels == 0 && !HasModuleSelectorLoc) {
if (LocationInfo == nullptr)
return nullptr;
return reinterpret_cast<SourceLoc const *>(&LocationInfo);
}
return reinterpret_cast<SourceLoc const *>(LocationInfo);
}
DeclNameLoc(const void *LocationInfo, unsigned NumArgumentLabels,
bool HasModuleSelectorLoc)
: LocationInfo(LocationInfo), NumArgumentLabels(NumArgumentLabels),
HasModuleSelectorLoc(HasModuleSelectorLoc) {}
public:
/// Create an invalid declaration name location.
DeclNameLoc() : DeclNameLoc(nullptr, 0, false) {}
/// Create declaration name location information for a base name.
explicit DeclNameLoc(SourceLoc baseNameLoc)
: DeclNameLoc(baseNameLoc.getOpaquePointerValue(), 0, false) {}
explicit DeclNameLoc(ASTContext &ctx, SourceLoc moduleSelectorLoc,
SourceLoc baseNameLoc)
: DeclNameLoc(ctx, moduleSelectorLoc, baseNameLoc,
SourceLoc(), {}, SourceLoc()) { }
/// Create declaration name location information for a compound
/// name.
DeclNameLoc(ASTContext &ctx, SourceLoc baseNameLoc,
SourceLoc lParenLoc,
ArrayRef<SourceLoc> argumentLabelLocs,
SourceLoc rParenLoc)
: DeclNameLoc(ctx, SourceLoc(), baseNameLoc,
lParenLoc, argumentLabelLocs, rParenLoc) { }
DeclNameLoc(ASTContext &ctx, SourceLoc moduleSelectorLoc,
SourceLoc baseNameLoc,
SourceLoc lParenLoc,
ArrayRef<SourceLoc> argumentLabelLocs,
SourceLoc rParenLoc);
/// Whether the location information is valid.
bool isValid() const { return getBaseNameLoc().isValid(); }
/// Whether the location information is invalid.
bool isInvalid() const { return getBaseNameLoc().isInvalid(); }
/// Whether this was written as a compound name.
bool isCompound() const { return NumArgumentLabels > 0; }
/// Retrieve the location of the base name.
SourceLoc getBaseNameLoc() const {
const SourceLoc *SourceLocs = getSourceLocs();
if (SourceLocs == nullptr)
return SourceLoc();
return SourceLocs[BaseNameIndex];
}
/// Retrieve the location of the left parentheses.
SourceLoc getLParenLoc() const {
if (NumArgumentLabels == 0) return SourceLoc();
return getSourceLocs()[LParenIndex];
}
/// Retrieve the location of the right parentheses.
SourceLoc getRParenLoc() const {
if (NumArgumentLabels == 0) return SourceLoc();
return getSourceLocs()[RParenIndex];
}
/// Retrieve the location of an argument label.
SourceLoc getArgumentLabelLoc(unsigned index) const {
if (index >= NumArgumentLabels)
return SourceLoc();
return getSourceLocs()[FirstArgumentLabelIndex + index];
}
SourceLoc getModuleSelectorLoc() const {
if (!HasModuleSelectorLoc) return SourceLoc();
return getSourceLocs()[ModuleSelectorIndex];
}
SourceLoc getStartLoc() const {
return HasModuleSelectorLoc ? getModuleSelectorLoc() : getBaseNameLoc();
}
SourceLoc getEndLoc() const {
return NumArgumentLabels == 0 ? getBaseNameLoc() : getRParenLoc();
}
/// Retrieve the complete source range for this declaration name.
SourceRange getSourceRange() const {
return SourceRange(getStartLoc(), getEndLoc());
}
};
}
#endif // SWIFT_AST_DECL_NAME_LOC_H