Darwin, libgcc : Adjust min version supported for the OS.

Tools from later versions of the OS deprecate or fail to support
earlier OS revisions.

libgcc/
	* config.host: Arrange to set min Darwin OS versions from
	the configured host version.
        * config/i386/t-darwin: Amend to handle configured min OS
	versions.
        * config/t-darwin : Use the configured min OS versions.
        * config/t-darwin-min-1: New.
        * config/t-darwin-min-4: New.
        * config/t-darwin-min-5: New.
        * config/t-darwin-min-8: New.

(cherry picked from commit a618c9ca6ba25235b23e403ec1b06dac6d760281)

Author: iains

libgcc/config.host

@@ -235,11 +235,33 @@ case ${host} in
       *-darwin*)
         echo "but is needed after macOS 10.11 (setting it on)" 1>&2
         tmake_file="$tmake_file t-darwin-rpath "
+        enable_darwin_at_rpath=yes
         ;;
     esac
   else
     echo "enable_darwin_at_rpath is '$enable_darwin_at_rpath'" 1>&2
   fi
+  case ${host} in
+    *-*-darwin20* | *-*-darwin1[89]*)
+      tmake_file="t-darwin-min-8 $tmake_file"
+      ;;
+    *-*-darwin9* | *-*-darwin1[0-7]*)
+      if test "x$enable_darwin_at_rpath" = "xyes"; then
+        tmake_file="t-darwin-min-5 $tmake_file"
+      else
+        tmake_file="t-darwin-min-4 $tmake_file"
+      fi
+      ;;
+    *-*-darwin[4-8]*)
+      tmake_file="t-darwin-min-1 $tmake_file"
+      ;;
+    *)
+      # Fall back to configuring for the oldest system known to work with the
+      # current sources.
+      tmake_file="t-darwin-min-5 $tmake_file"
+      echo "Warning: libgcc configured to support macOS 10.5" 1>&2
+      ;;
+  esac
   extra_parts="crt3.o d10-uwfef.o crttms.o crttme.o libemutls_w.a"
   ;;
 *-*-dragonfly*)

libgcc/config/t-darwin

@@ -1,15 +1,15 @@
 # Set this as a minimum (unless overriden by arch t-files) since it's a
 # reasonable lowest common denominator that works for all our archs.
-HOST_LIBGCC2_CFLAGS += -mmacosx-version-min=10.4
+HOST_LIBGCC2_CFLAGS += $(DARWIN_MIN_LIB_VERSION)
 
 crt3.o: $(srcdir)/config/darwin-crt3.c
-	$(crt_compile) -mmacosx-version-min=10.4 -c $<
+	$(crt_compile) $(DARWIN_MIN_CRT_VERSION) -c $<
 
 crttms.o: $(srcdir)/config/darwin-crt-tm.c
-	$(crt_compile) -mmacosx-version-min=10.4 -DSTART -c $<
+	$(crt_compile) $(DARWIN_MIN_CRT_VERSION) -DSTART -c $<
 
 crttme.o: $(srcdir)/config/darwin-crt-tm.c
-	$(crt_compile) -mmacosx-version-min=10.4 -DEND -c $<
+	$(crt_compile) $(DARWIN_MIN_CRT_VERSION) -DEND -c $<
 
 # Use unwind-dw2-fde-darwin
 LIB2ADDEH = $(srcdir)/unwind-dw2.c $(srcdir)/config/unwind-dw2-fde-darwin.c \
@@ -24,6 +24,8 @@ libemutls_w.a: emutls.o
 	$(RANLIB_FOR_TARGET) $@
 
 # Patch to __Unwind_Find_Enclosing_Function for Darwin10.
+# This has to be built for 10.6, even if the toolchain will not target that
+# version
 d10-uwfef.o: $(srcdir)/config/darwin10-unwind-find-enc-func.c
 	$(crt_compile) -mmacosx-version-min=10.6 -c $<
 

libgcc/config/t-darwin-min-1

@@ -0,0 +1,3 @@
+# Support building with -mmacosx-version-min back to 10.1.
+DARWIN_MIN_LIB_VERSION = -mmacosx-version-min=10.4
+DARWIN_MIN_CRT_VERSION = -mmacosx-version-min=10.1

libgcc/config/t-darwin-min-4

@@ -0,0 +1,3 @@
+# Support building with -mmacosx-version-min back to 10.4.
+DARWIN_MIN_LIB_VERSION = -mmacosx-version-min=10.4
+DARWIN_MIN_CRT_VERSION = -mmacosx-version-min=10.4

libgcc/config/t-darwin-min-5

@@ -0,0 +1,3 @@
+# Support building with -mmacosx-version-min back to 10.5.
+DARWIN_MIN_LIB_VERSION = -mmacosx-version-min=10.5
+DARWIN_MIN_CRT_VERSION = -mmacosx-version-min=10.5

libgcc/config/t-darwin-min-8

@@ -0,0 +1,3 @@
+# Support building with -mmacosx-version-min back to 10.8.
+DARWIN_MIN_LIB_VERSION = -mmacosx-version-min=10.8
+DARWIN_MIN_CRT_VERSION = -mmacosx-version-min=10.8

libgcc/config/t-darwin-rpath

@@ -1,5 +1,2 @@
 # Use @rpath and add a search path to exes and dylibs that depend on this.
 SHLIB_RPATH = @rpath
-
-# Which does not work for Darwin < 9
-HOST_LIBGCC2_CFLAGS += -mmacosx-version-min=10.5