Auto merge of rust-lang#25208 - lfairy:version-hash, r=brson

The code takes a prefix of the MD5 hash of the version string.

Since the hash command differs across GNU and BSD platforms, we scan for
the right one in the configure script.

Closes rust-lang#25007

Author: bors

configure

@@ -106,8 +106,8 @@ probe() {
         T=$(command -v $P 2>&1)
         if [ $? -eq 0 ]
         then
-            VER0=$($P --version 2>/dev/null | head -1 \
-                |  sed -e 's/[^0-9]*\([vV]\?[0-9.]\+[^ ]*\).*/\1/' )
+            VER0=$($P --version 2>/dev/null \
+                |  grep -o '[vV]\?[0-9][0-9.][a-z0-9.-]*' | head -1 )
             if [ $? -eq 0 -a "x${VER0}" != "x" ]
             then
               VER="($VER0)"
@@ -711,6 +711,20 @@ else
     probe_need CFG_GIT     git
 fi
 
+# Use `md5sum` on GNU platforms, or `md5 -q` on BSD
+probe CFG_MD5              md5
+probe CFG_MD5SUM           md5sum
+if [ -n "$CFG_MD5" ]
+then
+    CFG_HASH_COMMAND="$CFG_MD5 -q | head -c 8"
+elif [ -n "$CFG_MD5SUM" ]
+then
+    CFG_HASH_COMMAND="$CFG_MD5SUM | head -c 8"
+else
+    err 'could not find one of: md5 md5sum'
+fi
+putvar CFG_HASH_COMMAND
+
 probe CFG_CLANG            clang++
 probe CFG_CCACHE           ccache
 probe CFG_GCC              gcc

mk/main.mk

@@ -20,7 +20,9 @@ CFG_RELEASE_NUM=1.1.0
 # versions (section 9)
 CFG_PRERELEASE_VERSION=.1
 
-CFG_FILENAME_EXTRA=4e7c5e5c
+# Append a version-dependent hash to each library, so we can install different
+# versions in the same place
+CFG_FILENAME_EXTRA=$(shell printf '%s' $(CFG_RELEASE) | $(CFG_HASH_COMMAND))
 
 ifeq ($(CFG_RELEASE_CHANNEL),stable)
 # This is the normal semver version string, e.g. "0.12.0", "0.12.0-nightly"