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[cxx-interop] Work around crash in codegen when initializing C++ span #81030

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Merged
merged 1 commit into from
Apr 23, 2025
Merged

[cxx-interop] Work around crash in codegen when initializing C++ span #81030

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9 changes: 9 additions & 0 deletions lib/ClangImporter/ImportDecl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4110,6 +4110,15 @@ namespace {
if (ctordecl->isCopyConstructor() || ctordecl->isMoveConstructor())
return nullptr;

// Don't import the generic ctors of std::span, rely on the ctors that
// we instantiate when conforming to the overlay. These generic ctors
// can cause crashes in codegen.
// FIXME: figure out why.
const auto *parent = ctordecl->getParent();
if (funcTemplate && parent->isInStdNamespace() &&
parent->getIdentifier() && parent->getName() == "span")
return nullptr;

DeclName ctorName(Impl.SwiftContext, DeclBaseName::createConstructor(),
bodyParams);
result = Impl.createDeclWithClangNode<ConstructorDecl>(
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8 changes: 8 additions & 0 deletions test/Interop/Cxx/stdlib/use-std-span-typechecker.swift
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Expand Up @@ -11,3 +11,11 @@ arr.withUnsafeBufferPointer { ubpointer in
let _ = ConstSpanOfInt(ubpointer.baseAddress!, ubpointer.count)
// expected-warning@-1 {{'init(_:_:)' is deprecated: use 'init(_:)' instead.}}
}

arr.withUnsafeBufferPointer { ubpointer in
// FIXME: this crashes the compiler once we import span's templated ctors as Swift generics.
let _ = ConstSpanOfInt(ubpointer.baseAddress, ubpointer.count)
// expected-error@-1 {{value of optional type 'UnsafePointer<Int32>?' must be unwrapped to a value of type 'UnsafePointer<Int32>'}}
// expected-note@-2 {{coalesce using '??' to provide a default when the optional value contains 'nil'}}
// expected-note@-3 {{force-unwrap using '!' to abort execution if the optional value contains 'nil'}}
}