src/bin/sage-env [macOS]: Detect ld-classic when full XCode is in use

Author: Matthias Koeppe

src/bin/sage-env

@@ -373,7 +373,12 @@ if [ -n "$SAGE_LOCAL" ]; then
     # On OS X, test whether "ld-classic" is present in the installed
     # version of the command-line tools. If so, we add "-ld_classic"
     # to LD_FLAGS. See #36599.
-    if [ "$UNAME" = "Darwin" ] && [ -x "$(xcode-select -p)/usr/bin/ld-classic" ] ; then
+    # When the full XCode is installed and in use, for example after
+    # "sudo xcode-select -s /Applications/Xcode.app", then "xcode-select -p"
+    # gives "/Applications/Xcode.app/Contents/Developer", but "ld-classic"
+    # is not in the subdirectory "usr/bin/" but rather in the subdirectory
+    # "Toolchains/XcodeDefault.xctoolchain/usr/bin/". See #37237.
+    if [ "$UNAME" = "Darwin" ] && [ -x "$(xcode-select -p)/usr/bin/ld-classic" -o -x "$(xcode-select -p)/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld-classic" ] ; then
         LDFLAGS="-L$SAGE_LOCAL/lib -Wl,-ld_classic,-rpath,$SAGE_LOCAL/lib $LDFLAGS"
     else
         LDFLAGS="-L$SAGE_LOCAL/lib -Wl,-rpath,$SAGE_LOCAL/lib $LDFLAGS"