Infrastructure support / fixes for making compiler server the default (#14279)

* Fix enabling the compiler server using autogen, and force it off if mcs is being used

* autogen updates

* Formatting fixes

* Fix vbcs getting turned on if unspecified even if mcs was selected

* Dynamically evaluate ENABLE_COMPILER_SERVER each time we compile instead of evaluating it once at some arbitrary point during makefile evaluation

* More detailed comment based on testing

* Handle the /shared option in genproj so it doesn't fail

* Raise basic profile check requirement to 6.2 and hopefully assert that named pipes work

* Default compiler server to off for now.

5 files changed, 38 insertions, 11 deletions

diff --git a/configure.ac b/configure.ac
index 57ee60b7aa2..d5c8ecc09c7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -6529,6 +6529,26 @@ if test x$host_darwin = xyes; then
    sed -e 's,lock_old_archive_extraction=yes,lock_old_archive_extraction=no,g' < libtool > libtool.new && mv libtool.new libtool && chmod +x libtool
 fi
 
+AC_MSG_CHECKING([compiler server])
+AC_ARG_WITH(compiler-server, [  --with-compiler-server=yes,no,default      Enables or disables compiler server],[
+   if test x$withval = xyes; then
+       enable_compiler_server=yes;
+   elif test x$withval = xno; then
+       enable_compiler_server=no;
+   elif test x$withval = xdefault; then
+       enable_compiler_server=no;
+   else
+       AC_MSG_ERROR([You must supply one of "yes", "no" or "default" to the --with-compiler-server option])
+   fi
+],[enable_compiler_server=no])
+
+if test x$enable_compiler_server = xyes; then
+   if test x$csc_compiler = xmcs; then
+       AC_MSG_WARN([mcs does not support the compiler server])
+       enable_compiler_server=no;
+   fi
+fi
+
 (
   case $prefix in
   NONE) prefix=$ac_default_prefix ;;
@@ -6699,8 +6719,9 @@ if test x$buildsgen = xyes; then
 fi
 	
 echo "
-        mcs source:    $mcsdir
+	mcs source:    $mcsdir
 	C# Compiler:   $csc_compiler
+	CompilerServer:$enable_compiler_server
 
    Engine:
 	Host:	       $host
diff --git a/mcs/build/common/basic-profile-check.cs b/mcs/build/common/basic-profile-check.cs
index 6fe2fe7ccf8..f4ac1302ddd 100644
--- a/mcs/build/common/basic-profile-check.cs
+++ b/mcs/build/common/basic-profile-check.cs
@@ -41,9 +41,9 @@ class X
 
 		Version min_mono_version;
 #if __MonoCS__
-		min_mono_version = new Version (5, 19);
+		min_mono_version = new Version (6, 2);
 #else
-		min_mono_version = new Version (5, 10);
+		min_mono_version = new Version (6, 2);
 #endif
 
 		if (version < min_mono_version)
diff --git a/mcs/build/rules.make b/mcs/build/rules.make
index b4c9df71575..0aaccdf58a8 100644
--- a/mcs/build/rules.make
+++ b/mcs/build/rules.make
@@ -31,13 +31,15 @@ ifndef BUILD_TOOLS_PROFILE
 BUILD_TOOLS_PROFILE = build
 endif
 
-ifeq ("$(ENABLE_COMPILER_SERVER)","1")
-COMPILER_SERVER_ARGS=/shared:$(COMPILER_SERVER_PIPENAME)
-CSC_LOCATION=$(SERVER_CSC_LOCATION)
-else
-COMPILER_SERVER_ARGS:=
-CSC_LOCATION=$(STANDALONE_CSC_LOCATION)
-endif
+# NOTE: We have to use conditional functions to branch on the state of ENABLE_COMPILER_SERVER
+#  because the value of this flag can change after rules.make is evaluated. If we use regular ifeq
+#  statements our builds will opt to use or not use the compiler server seemingly at random because
+#  we include rules.make many times and the last observed value from rules.make does not match the
+#  value used when actually executing csc. you can observe this by adding an $ ( info here and an
+#  echo above the csc invocation and printing the values.
+COMPILER_SERVER_ENABLED_ARGS = /shared:$(COMPILER_SERVER_PIPENAME)
+COMPILER_SERVER_ARGS = $(if $(findstring 1,$(ENABLE_COMPILER_SERVER)),$(COMPILER_SERVER_ENABLED_ARGS),)
+CSC_LOCATION = $(if $(findstring 1,$(ENABLE_COMPILER_SERVER)),$(SERVER_CSC_LOCATION),$(STANDALONE_CSC_LOCATION))
 
 USE_MCS_FLAGS = $(COMPILER_SERVER_ARGS) /codepage:$(CODEPAGE) /nologo /noconfig /deterministic $(LOCAL_MCS_FLAGS) $(PLATFORM_MCS_FLAGS) $(PROFILE_MCS_FLAGS) $(MCS_FLAGS)
 USE_MBAS_FLAGS = $(COMPILER_SERVER_ARGS) /codepage:$(CODEPAGE) $(LOCAL_MBAS_FLAGS) $(PLATFORM_MBAS_FLAGS) $(PROFILE_MBAS_FLAGS) $(MBAS_FLAGS)
diff --git a/mcs/build/start-compiler-server.sh b/mcs/build/start-compiler-server.sh
index 26be16ed000..b7df8cf969f 100755
--- a/mcs/build/start-compiler-server.sh
+++ b/mcs/build/start-compiler-server.sh
@@ -7,7 +7,8 @@ set -e
 
 if [ -s "$VBCS_LOCATION" ]; then
     CMD="RoslynCommandLineLogFile=$2 $VBCS_RUNTIME --gc-params=nursery-size=64m \"$VBCS_LOCATION\" -pipename:$3 &"
-    echo . > "$2"
+    echo "Log location set to $2"
+    touch "$2"
     echo "cd $1; bash -c \"$CMD\""
     cd "$1"
     bash -c "$CMD"
diff --git a/msvc/scripts/genproj.cs b/msvc/scripts/genproj.cs
index 1849009db00..79d9c4c3c26 100755
--- a/msvc/scripts/genproj.cs
+++ b/msvc/scripts/genproj.cs
@@ -716,6 +716,9 @@ public class MsbuildGenerator {
 
 		case "/sourcelink":
 			return true;
+
+		case "/shared":
+			return true;
 		}
 
 		Console.Error.WriteLine ($"// Failing with : {arg}");