file: Update GET_RUNTIME_DEPENDENCIES for macOS 11 dylib cache

Starting on macOS 11, the dynamic loader has a builtin cache of
system-provided dylib files.  They do not actually exist on the
filesystem.  However, runtime dependencies recorded in Mach-O binaries
can still have `LC_LOAD_DYLIB` entries referring to such dylib files by
absolute path.  The dynamic loader simply resolves the paths from its
cache.  Teach `file(GET_RUNTIME_DEPENDENCIES)` to skip dependencies on
such dylib paths.  For practical software distribution purposes they do
not exist, or at least can be assumed available on all deployments.

Issue: #20863

1 files changed, 14 insertions, 1 deletions

diff --git a/Source/cmBinUtilsMacOSMachOLinker.cxx b/Source/cmBinUtilsMacOSMachOLinker.cxx
index 98250b1..0f47146 100644
--- a/Source/cmBinUtilsMacOSMachOLinker.cxx
+++ b/Source/cmBinUtilsMacOSMachOLinker.cxx
@@ -14,6 +14,18 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
+namespace {
+bool IsMissingSystemDylib(std::string const& path)
+{
+  // Starting on macOS 11, the dynamic loader has a builtin cache of
+  // system-provided dylib files that do not exist on the filesystem.
+  // Tell our caller that these are expected to be missing.
+  return ((cmHasLiteralPrefix(path, "/System/Library/") ||
+           cmHasLiteralPrefix(path, "/usr/lib/")) &&
+          !cmSystemTools::PathExists(path));
+}
+}
+
 cmBinUtilsMacOSMachOLinker::cmBinUtilsMacOSMachOLinker(
   cmRuntimeDependencyArchive* archive)
   : cmBinUtilsLinker(archive)
@@ -82,7 +94,8 @@ bool cmBinUtilsMacOSMachOLinker::GetFileDependencies(
         return false;
       }
       if (resolved) {
-        if (!this->Archive->IsPostExcluded(path)) {
+        if (!this->Archive->IsPostExcluded(path) &&
+            !IsMissingSystemDylib(path)) {
           auto filename = cmSystemTools::GetFilenameName(path);
           bool unique;
           this->Archive->AddResolvedPath(filename, path, unique);