[lld/mac] For catalyst outputs, tolerate implicitly linking against arm64e mac tbd files (#193065)

Some mac libraries published in the Xcode SDK are now arm64e only, and
catalyst applications should be able to link against these even if
building for arm64.

This matches ld-prime behavior.

https://reviews.llvm.org/D124336 allows linking against MacOS libraries,
but only if the architecture matches exactly.
https://reviews.llvm.org/D130683 allows linking against tbds with ABI
compatibility architectures, but the logic isn't used for this
particular case.

[Assisted-by](https://t.ly/Dkjjk): [Claude Opus
4.6](https://www.anthropic.com/news/claude-opus-4-6)

---------

Co-authored-by: Nuri Amari <nuriamari@fb.com>

lld/MachO/InputFiles.cpp

@@ -1858,15 +1858,6 @@ constexpr std::array<StringRef, 3> skipPlatformChecks{
     "/usr/lib/system/libsystem_platform.dylib",
     "/usr/lib/system/libsystem_pthread.dylib"};
 
-static bool skipPlatformCheckForCatalyst(const InterfaceFile &interface,
-                                         bool explicitlyLinked) {
-  // Catalyst outputs can link against implicitly linked macOS-only libraries.
-  if (config->platform() != PLATFORM_MACCATALYST || explicitlyLinked)
-    return false;
-  return is_contained(interface.targets(),
-                      MachO::Target(config->arch(), PLATFORM_MACOS));
-}
-
 static bool isArchABICompatible(ArchitectureSet archSet,
                                 Architecture targetArch) {
   uint32_t cpuType;
@@ -1879,6 +1870,18 @@ static bool isArchABICompatible(ArchitectureSet archSet,
   });
 }
 
+static bool skipPlatformCheckForCatalyst(const InterfaceFile &interface,
+                                         bool explicitlyLinked) {
+  // Catalyst outputs can link against implicitly linked macOS-only libraries.
+  if (config->platform() != PLATFORM_MACCATALYST || explicitlyLinked)
+    return false;
+  ArchitectureSet macOSArchs;
+  for (const auto &target : interface.targets())
+    if (target.Platform == PLATFORM_MACOS)
+      macOSArchs.set(target.Arch);
+  return isArchABICompatible(macOSArchs, config->arch());
+}
+
 static bool isTargetPlatformArchCompatible(
     InterfaceFile::const_target_range interfaceTargets, Target target) {
   if (is_contained(interfaceTargets, target))

lld/test/MachO/catalyst-arm64e-reexport.s

@@ -0,0 +1,50 @@
+# REQUIRES: aarch64
+
+## When linking a macCatalyst arm64 output, lld should tolerate implicitly
+## linked re-exported dylibs that only declare arm64e-macos targets, even if targeting arm64.
+# arm64 and arm64e are ABI compatible (same CPU type), and ld64 accepts this.
+
+# RUN: rm -rf %t; split-file --no-leading-lines %s %t
+
+# RUN: llvm-mc -filetype=obj -triple=arm64-apple-ios13.15.0-macabi -o %t/test.o /dev/null
+
+# RUN: %no-arg-lld -syslibroot %t/sdk -lSystem -dylib -arch arm64 \
+# RUN:     -platform_version mac-catalyst 13.15.0 14.0 %t/test.o -o /dev/null
+
+## Explicitly linking an arm64e-macos-only library should still be an error.
+# RUN: not %no-arg-lld -syslibroot %t/sdk -lSystem -dylib -arch arm64 \
+# RUN:     -platform_version mac-catalyst 13.15.0 14.0 %t/test.o -o /dev/null \
+# RUN:     -L %t/explicit -larm64e_only 2>&1 | FileCheck %s
+# CHECK: libarm64e_only.dylib) is incompatible with arm64 (macCatalyst13.15.0)
+
+#--- sdk/usr/lib/libSystem.tbd
+--- !tapi-tbd
+tbd-version:      4
+targets:          [ arm64-macos, arm64-maccatalyst ]
+install-name:     '/usr/lib/libSystem.dylib'
+current-version:  0001.001.1
+reexported-libraries:
+  - targets:      [ arm64-macos, arm64-maccatalyst ]
+    libraries:    [ '/usr/lib/system/libsystem_eligibility.dylib' ]
+--- !tapi-tbd
+tbd-version:      4
+targets:          [ x86_64-macos, arm64e-macos ]
+install-name:     '/usr/lib/system/libsystem_eligibility.dylib'
+current-version:  0001.001.1
+parent-umbrella:
+  - targets:      [ x86_64-macos, arm64e-macos ]
+    umbrella:     System
+exports:
+  - targets:      [ x86_64-macos, arm64e-macos ]
+    symbols:      [ _os_eligibility_get_domain_answer ]
+...
+#--- explicit/libarm64e_only.tbd
+--- !tapi-tbd
+tbd-version:      4
+targets:          [ x86_64-macos, arm64e-macos ]
+install-name:     '/usr/lib/libarm64e_only.dylib'
+current-version:  0001.001.1
+exports:
+  - targets:      [ x86_64-macos, arm64e-macos ]
+    symbols:      [ _arm64e_only_func ]
+...