[Bug driver/63810] gcc sets incorrect macro for OS X deployment targets

[jeremyhu at macports dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63810

--- Comment #1 from Jeremy Huddleston Sequoia <jeremyhu at macports dot org> ---
Larry said that he's working on a patch to fix this for gcc trunk, and I
suspect he's pretty close to having something since that was about a week ago.

The algorithm for determining what the macro should be is quite simple:

Split the string by "."
Use implicit "0" if there are less than three elements.
if (first field is >10) or (first field is 10 and second field >= 10), use
"%02d%02d%02d" as the format
else use "%02d%01d%01d" as the format

I had to do this in bash for some unrelated reason, and here it is in case it
is helpful to you:

BUILD_MAJOR=$(echo ${PRODUCT_VERSION} | cut -f1 -d.)
BUILD_MINOR=$(echo ${PRODUCT_VERSION} | cut -f2 -d.)
BUILD_TINY=$(echo ${PRODUCT_VERSION} | cut -f3 -d.)

[[ -z "${BUILD_MINOR}" ]] && BUILD_MINOR="0"
[[ -z "${BUILD_TINY}" ]] && BUILD_TINY="0"

if ((BUILD_MAJOR > 10 || (BUILD_MAJOR == 10 && BUILD_MINOR >= 10))) ; then
  VERSION_ENCODED=$(printf "%02d%02d%02d" ${BUILD_MAJOR} ${BUILD_MINOR}
${BUILD_TINY})
else
  VERSION_ENCODED=$(printf "%02d%01d%01d" ${BUILD_MAJOR} ${BUILD_MINOR}
${BUILD_TINY})
fi

For clang, I did this (slightly less clean):

-    char Str[5];
-    Str[0] = '0' + (Maj / 10);
-    Str[1] = '0' + (Maj % 10);
-    Str[2] = '0' + std::min(Min, 9U);
-    Str[3] = '0' + std::min(Rev, 9U);
-    Str[4] = '\0';
+    char Str[7];
+    if (Maj < 10 || Maj == 10 && Min < 10) {
+      Str[0] = '0' + (Maj / 10);
+      Str[1] = '0' + (Maj % 10);
+      Str[2] = '0' + std::min(Min, 9U);
+      Str[3] = '0' + std::min(Rev, 9U);
+      Str[4] = '\0';
+    } else {
+      Str[0] = '0' + (Maj / 10);
+      Str[1] = '0' + (Maj % 10);
+      Str[2] = '0' + (Min / 10);
+      Str[3] = '0' + (Min % 10);
+      Str[4] = '0' + (Rev / 10);
+      Str[5] = '0' + (Rev % 10);
+      Str[6] = '\0';
+    }