[libc++] Add a few basic tests for C++ / Swift interoperation

[ldionne]

These tests are only enabled on Apple platforms. The purpose of these tests is to ensure that we don't break existing functionality powered by Clang modules as we refactor the modulemap, since Swift interop greatly exercises libc++'s support for Clang modules.

In particular, adding these tests to libc++ is not an official statement of support from libc++ towards Swift interop (which would require a community consensus that I am not pursuing at this time), but rather a way for us to find out when we unexpectedly break things so we can decide how / whether we want to address such breakage.

Once the refactoring of the modulemap started in #98214 is mostly done, it would be reasonable to remove these tests unless libc++ wants to pursue support for Swift interop more officially.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Louis Dionne (ldionne)

Changes

These tests are only enabled on Apple platforms. The purpose of these tests is to ensure that we don't break existing functionality powered by Clang modules as we refactor the modulemap, since Swift interop greatly exercises libc++'s support for Clang modules.

In particular, adding these tests to libc++ is not an official statement of support from libc++ towards Swift interop (which would require a community consensus that I am not pursuing at this time), but rather a way for us to find out when we unexpectedly break things so we can decide how / whether we want to address such breakage.

Once the refactoring of the modulemap started in #98214 is mostly done, it would be reasonable to remove these tests unless libc++ wants to pursue support for Swift interop more officially.

---

Full diff: https://github.com/llvm/llvm-project/pull/104863.diff

5 Files Affected:

• (added) libcxx/test/libcxx/vendor/apple/swift-interop.sh.cpp (+21)
• (added) libcxx/test/libcxx/vendor/apple/swift-interop/string/main.swift (+13)
• (added) libcxx/test/libcxx/vendor/apple/swift-interop/vector/header.h (+13)
• (added) libcxx/test/libcxx/vendor/apple/swift-interop/vector/main.swift (+13)
• (added) libcxx/test/libcxx/vendor/apple/swift-interop/vector/module.modulemap (+4)

diff --git a/libcxx/test/libcxx/vendor/apple/swift-interop.sh.cpp b/libcxx/test/libcxx/vendor/apple/swift-interop.sh.cpp
new file mode 100755
index 00000000000000..87c6c80f62a7eb
--- /dev/null
+++ b/libcxx/test/libcxx/vendor/apple/swift-interop.sh.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// This test requires access to the Swift compiler, which we assume is only available on Apple
+// platforms for now.
+// REQUIRES: buildhost=darwin
+
+// std::string basic test
+// RUN: swiftc -cxx-interoperability-mode=default %S/swift-interop/string/main.swift -o %t.string.exe \
+// RUN:   -Xcc -nostdinc++ -Xcc -nostdlib++ -Xcc -isystem -Xcc "%{include-dir}"
+// RUN: %{exec} %t.string.exe
+
+// std::vector test with a modulemap
+// RUN: swiftc -cxx-interoperability-mode=default %S/swift-interop/vector/main.swift -o %t.vector.exe \
+// RUN:   -Xcc -nostdinc++ -Xcc -nostdlib++ -Xcc -isystem -Xcc "%{include-dir}" -Xcc -I -Xcc %S/swift-interop/vector
+// RUN: %{exec} %t.vector.exe
diff --git a/libcxx/test/libcxx/vendor/apple/swift-interop/string/main.swift b/libcxx/test/libcxx/vendor/apple/swift-interop/string/main.swift
new file mode 100755
index 00000000000000..1b2e12f839ba7d
--- /dev/null
+++ b/libcxx/test/libcxx/vendor/apple/swift-interop/string/main.swift
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+import CxxStdlib
+
+let s: std.string = "abc123"
+
+for char in s { print(char) }
diff --git a/libcxx/test/libcxx/vendor/apple/swift-interop/vector/header.h b/libcxx/test/libcxx/vendor/apple/swift-interop/vector/header.h
new file mode 100644
index 00000000000000..de41747de05155
--- /dev/null
+++ b/libcxx/test/libcxx/vendor/apple/swift-interop/vector/header.h
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <vector>
+
+using VectorOfInt = std::vector<int>;
+
+inline VectorOfInt getStdVector() { return {1, 2, 3}; }
diff --git a/libcxx/test/libcxx/vendor/apple/swift-interop/vector/main.swift b/libcxx/test/libcxx/vendor/apple/swift-interop/vector/main.swift
new file mode 100644
index 00000000000000..6ec3640881424d
--- /dev/null
+++ b/libcxx/test/libcxx/vendor/apple/swift-interop/vector/main.swift
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+import MyCxxDep // no explicit import of CxxStdlib
+
+let vec = getStdVector()
+
+for it in vec { print(it) }
diff --git a/libcxx/test/libcxx/vendor/apple/swift-interop/vector/module.modulemap b/libcxx/test/libcxx/vendor/apple/swift-interop/vector/module.modulemap
new file mode 100644
index 00000000000000..8dabb571262613
--- /dev/null
+++ b/libcxx/test/libcxx/vendor/apple/swift-interop/vector/module.modulemap
@@ -0,0 +1,4 @@
+module MyCxxDep {
+    header "header.h"
+    export *
+}

[ldionne]

Closing since the modulemap generation work has been done.

This was prevented from landing due to the macOS builders having a version of Xcode that was too old.