ENH: forward edit of gcc version to foamConfigurePaths

- foamConfigurePaths (1812) now supports a -gcc option.
  Eg,
      foamConfigurePaths -gcc gcc-4.8.5

  This avoids fragile complier versioning that was previously
  hardcoded into the legacyCompile script.

legacyCompile/legacyCompile

@@ -270,32 +270,6 @@ sed -n \
 
 #------------------------------------------------------------------------------
 
-# Special treatment for gcc sub-components (needs rethinking)
-case "$compilerVERSION" in
-Gcc | Gcc48)
-    gccVERSION=gcc-4.8.5   # match value in config.sh/compiler
-    ;;
-Gcc49)
-    gccVERSION=gcc-4.9.3   # match value in config.sh/compiler
-    ;;
-Gcc62)
-    gccVERSION=gcc-6.2.0   # match value in config.sh/compiler
-    ;;
-Gcc63)
-    gccVERSION=gcc-6.3.0   # match value in config.sh/compiler
-    ;;
-Gcc71)
-    gccVERSION=gcc-7.1.0   # match value in config.sh/compiler
-    ;;
-Gcc*)
-    echo "Error: unconfigured gcc version '$compilerVERSION'"
-    exit 1 # Really exit, since this must be an input error
-    ;;
-esac
-# -----------------------------------------------------------------------------
-# NO FURTHER EDITING BELOW THIS LINE
-#------------------------------------------------------------------------------
-
 # Name of qt source directory is a fixed value
 qtSource="qt-everywhere-opensource-src-${qtVERSION##*-}"
 
@@ -528,6 +502,58 @@ _ifDifferent()
     [ "$#" -eq 3 -a "$2" != "$3" ] && echo "$1 $2"
 }
 
+
+# Function to do replacement on file. Checks if any replacement has been done.
+# _inlineSed <file> <regexp> <replacement> <msg>
+_inlineSed()
+{
+    local file="$1"
+    local regexp="$2"
+    local replacement="$3"
+    local msg="$4"
+    local cmd='/^[^#]/s@'"$regexp"'@'"$replacement"'@'
+
+    [ -f "$file" ] || {
+        echo "Missing file: $file"
+        exit 2 # Fatal
+    }
+
+    grep -q "$regexp" "$file" && sed -i -e "$cmd" "$file" || { \
+        echo "Failed: ${msg:-replacement} in $file"
+        return 1
+    }
+
+    [ -n "$msg" ] && echo "    $msg  ($file)"
+
+    return 0
+}
+
+
+# Standard <key> <val> type of replacements.
+# replace <file> <key1> <val1> .. <keyN> <valN>
+# looks for KEYWORD=.*
+replace()
+{
+    local file="$1"
+    shift
+
+    local key val
+
+    while [ "$#" -ge 2 ]
+    do
+        key=$1
+        val=$2
+        shift 2
+
+        _inlineSed \
+            $file  \
+            "$key=.*" \
+            "$key=$val" \
+            "Replaced $key setting by '$val'"
+    done
+}
+
+
 #
 # Unpack files and make any adjustments
 #
@@ -570,6 +596,7 @@ unpackAllFiles()
     _mvdir "$TPsource" "$TPdirName"
     _mvdir ThirdParty-plus "$TPdirName"
 
+    echo
 
     cd $INSTALL_DIR/$OFdirName || {
         echo "Error: cannot change to $INSTALL_DIR/$OFdirName"
@@ -585,6 +612,9 @@ unpackAllFiles()
 
     if true
     then
+        # Pre-1812, no -gcc option for foamConfigurePaths
+        hasOptGcc="$(exec /bin/sh $foamConfigure -help 2>&1 | sed -ne 's/^ *-gcc.*$/true/p')"
+
         # Compiler configuration (already sanity checked much further above)
         compilerOpt="-$compilerTypeVERSION $compilerVERSION"
         case "$compilerTypeVERSION:$compilerVERSION" in
@@ -592,6 +622,17 @@ unpackAllFiles()
             compilerOpt="$compilerOpt -clang $llvmVERSION"
             ;;
         third:Gcc*)
+            case "$hasOptGcc:$gccVERSION" in
+            (true:gcc-[1-9]*)
+                # Can use the -gcc option, and have gcc-version
+                compilerOpt="$compilerOpt -gcc $gccVERSION"
+                ;;
+            (:gcc-[1-9]*)
+                # Manual edit for gcc-version
+                echo "Simulated '-gcc $gccVERSION' option manually"
+                replace etc/config.sh/compiler gcc_version "$gccVERSION"
+                ;;
+            esac
             compilerOpt="$compilerOpt $gmpVERSION $mpfrVERSION $mpcVERSION"
             ;;
         esac
@@ -607,6 +648,7 @@ unpackAllFiles()
                 _ifDifferent -fftw    $fftwVERSION    $fftwDEFAULT
                 _ifDifferent -scotch  $scotchVERSION  $scotchDEFAULT
                 _ifDifferent -kahip   $kahipVERSION   $kahipDEFAULT
+                _ifDifferent -metis   $metisVERSION   $metisDEFAULT
                 _ifDifferent -openmpi $openmpiVERSION $openmpiDEFAULT
             )
 
@@ -633,6 +675,7 @@ unpackAllFiles()
     _unpackIfDifferent $fftwVERSION     $fftwDEFAULT
     _unpackIfDifferent $scotchVERSION   $scotchDEFAULT
     _unpackIfDifferent $kahipVERSION    $kahipDEFAULT
+    _unpackIfDifferent $metisVERSION    $metisDEFAULT
     _unpackIfDifferent $openmpiVERSION  $openmpiDEFAULT
 
     case "$compilerTypeVERSION:$compilerVERSION" in