macOS: If using Xcode CLT >= 15, add -Wl,-ld_classic in create_sysimg_from_object_file()

src/PackageCompiler.jl

@@ -14,9 +14,13 @@
 
 export create_sysimage, create_app, create_library
 
-include("juliaconfig.jl")
+# Vendored:
 include("../ext/TerminalSpinners.jl")
+
+# Source code for this package:
+include("juliaconfig.jl")
 include("library_selection.jl")
+include("xcode.jl")
 
 
 ##############
@@ -711,7 +715,15 @@
     end
     mkpath(dirname(sysimage_path))
     # Prevent compiler from stripping all symbols from the shared lib.
-    o_file_flags = Sys.isapple() ? `-Wl,-all_load $object_files` : `-Wl,--whole-archive $object_files -Wl,--no-whole-archive`
+    if Sys.isapple()
+        if _is_xcode_clt_and_is_gte_xcode_15()
+            o_file_flags = `-Wl,-all_load $object_files -Wl,-ld_classic`
+        else
+            o_file_flags = `-Wl,-all_load $object_files`
+        end
+    else
+        o_file_flags = `-Wl,--whole-archive $object_files -Wl,--no-whole-archive`
+    end
     extra = get_extra_linker_flags(version, compat_level, soname)
     cmd = `$(bitflag()) $(march()) -shared -L$(julia_libdir()) -L$(julia_private_libdir()) -o $sysimage_path $o_file_flags $(Base.shell_split(ldlibs())) $extra`
     run_compiler(cmd; cplusplus=true)

src/xcode.jl

@@ -0,0 +1,61 @@
+# Get the compiler command from `get_compiler_cmd()`, and run `cc --version`, and parse the
+# output to determine whether or not the compiler is an Xcode Clang.
+#
+# The return value is a NamedTuple of the form (; b, ver)
+# b = a Bool that is true iff the compiler is an Xcode Clang.
+# ver = the version number of the Xcode Clang. If it's not Xcode Clang, ver is nothing.
+function _is_xcode_clt()
+    cmd = `$(get_compiler_cmd()) --version`
+    @debug "_active_compiler_is_xcode_clt(): Attempting to run command" cmd
+    # The `ignorestatus` allows us to proceed if the command does not run successfully.
+    output = "\n" * strip(read(ignorestatus(cmd), String)) * "\n"
+
+    # If this is an Xcode Clang compiler, example output would be:
+    # > Apple clang version 16.0.0 (clang-1600.0.26.3)
+    # > Target: arm64-apple-darwin23.6.0
+    # > Thread model: posix
+    # > InstalledDir: /Library/Developer/CommandLineTools/usr/bin
+
+    installed_dir_m = match(r"\nInstalledDir: ([\w\/]*?)\n", output)
+    if isnothing(installed_dir_m)
+        return (; b=false, ver=nothing)
+    end
+    installed_dir_str = strip(installed_dir_m[1])
+    is_xcode_app = startswith(installed_dir_str, "/Applications/Xcode.app")
+    is_xcode_clt = startswith(installed_dir_str, "/Library/Developer/CommandLineTools")
+    if is_xcode_app || is_xcode_clt
+        m = match(r"\nApple clang version ([0-9\.]*?) ", output)
+        if isnothing(m)
+            @warn "Could not determine the version of the Xcode Command Line Tools"
+            (; b=false, ver=nothing)
+        end
+        ver_str = strip(m[1])
+        ver = tryparse(VersionNumber, ver_str)
+        if isnothing(ver)
+            @warn "Could not determine the version of the Xcode Command Line Tools" ver_str
+            (; b=false, ver=nothing)
+        end
+        b = true
+    else
+        b = false
+        ver = nothing
+    end
+    return (; b, ver)
+end
+
+# Return true iff the compiler is Xcode Clang AND the Xcode CLT version is >= 15.
+#
+# If the user sets the JULIA_PACKAGECOMPILER_XCODE_CLT_MAJOR_VERSION environment variable,
+# we skip our attempt at auto-detection, and instead use whatever value the user gave us.
+function _is_xcode_clt_and_is_gte_xcode_15()
+    str = strip(get(ENV, "JULIA_PACKAGECOMPILER_XCODE_CLT_MAJOR_VERSION", ""))
+    ver_int = tryparse(Int, str)
+    (ver_int isa Int) && return (ver_int >= 15)
+
+    result = _is_xcode_clt()
+    if result.b
+        return result.ver >= v"15"
+    else
+        return false
+    end
+end