[m-rev.] diff: delete --with-msvcrt configure option

[Julien Fischer]

Delete --with-msvcrt configure option.

The --with-msvcrt option was intended for selecting between the older Microsoft
C runtime (crtdll.dll) and the Microsoft Visual C runtime (msvcrt.dll). This is
all now ancient history, since the MSVCRT itself has been superseded by the
Universal C runtime since Windows 10. Delete the --with-msvcrt option and all
uses of it.

configure.ac:
    Delete the --with-msvcrt option.

scripts/mgnuc.in
scripts/ml.in:
    Delete uses of the above configuration value.

Documentation/README.MS-VisualC.md:
    Delete references to --with-msvcrt.

Julien.

diff --git a/Documentation/README.MS-VisualC.md
b/Documentation/README.MS-VisualC.md
index 0881c15b9..2bd1749e3 100644
--- a/Documentation/README.MS-VisualC.md
+++ b/Documentation/README.MS-VisualC.md
@@ -86,13 +86,7 @@ cross-compile the MSVC port.
 In either case, to use MSVC as the C compiler with Mercury, invoke `configure`
 as follows:

-
-    ./configure --with-cc=cl [--with-msvcrt] [<any other options>]
-
-
-The `--with-msvcrt` flag causes executables built with this install of Mercury
-to be linked with the MS Visual C runtime, instead of the standard libC
-runtime.
+    ./configure --with-cc=cl [<any other options>]

 On Cygwin, `configure` and `mmake` will do translation of Unix style paths, so
 you may specify the installation directory using either a Unix- or
@@ -100,28 +94,20 @@ Windows-style path. On MSYS2, you must use a full
Windows-style path with a
 drive letter, except that you must use `/` instead of `\` as a directory
 separator. For example, this is acceptable:

-
     ./configure --prefix="c:/where/to/install/mercury"

-
 but this is not:

-
     ./configure --prefix="c:\where\to\install\mercury"

-
 Once `configure` has successfully finished, then do

-
     make

-
 and then

-
     make install

-
 as normal.

 Limitations
diff --git a/configure.ac b/configure.ac
index 35b82c52e..4dfb3e550 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5089,28 +5089,6 @@ fi

 #-----------------------------------------------------------------------------#

-AC_ARG_WITH(msvcrt,
-    AS_HELP_STRING([--with-msvcrt],
-                   [use the MS Visual C runtime if using MS C compiler.]),
-    mercury_cv_msvcrt=yes,mercury_cv_msvcrt=no)
-
-AC_MSG_CHECKING(whether to use the MS Visual C Runtime)
-if test "$mercury_cv_msvcrt" = "yes"; then
-    if test "$ac_microsoft" = "yes"; then
-        AC_MSG_RESULT(yes)
-        USE_MSVCRT=yes
-    else
-        AC_MSG_RESULT(no as not using the MS C compiler)
-        USE_MSVCRT=no
-    fi
-else
-    AC_MSG_RESULT(no)
-    USE_MSVCRT=no
-fi
-AC_SUBST(USE_MSVCRT)
-
-#-----------------------------------------------------------------------------#
-
 AC_ARG_ENABLE(lto,
     AS_HELP_STRING([--enable-lto],
                    [Enable link-time optimization for C grades
(experimental)]),
diff --git a/scripts/mgnuc.in b/scripts/mgnuc.in
index f60c90f37..3af04f517 100644
--- a/scripts/mgnuc.in
+++ b/scripts/mgnuc.in
@@ -320,22 +320,6 @@ case ${threadscope} in
     false)      THREADSCOPE_OPTS="" ;;
 esac

-# Set the correct flags if we are to use the MS Visual C runtime.
-use_msvcrt=@USE_MSVCRT@
-if test ${use_msvcrt} = "yes"
-then
-    case ${thread_safe} in
-        # -MD states that we will use the MSVC runtime, the boehm_gc collector
-        # assumes that the collector has been built as a DLL if we are using
-        # the MSVC runtime so we need to define GC_NOT_DLL when the collector
-        # isn't built as a DLL.
-        true)   MSVCRT_OPTS="-MD" ;;
-        false)  MSVCRT_OPTS="-DGC_NOT_DLL -MD" ;;
-    esac
-else
-    MSVCRT_OPTS=""
-fi
-
 boehm_opts="-DMR_CONSERVATIVE_GC -DMR_BOEHM_GC "
 case ${gc_method} in
     accurate)       GC_OPTS="-DMR_NATIVE_GC" ;;
diff --git a/scripts/ml.in b/scripts/ml.in
index 06d63bb8d..f8b1032fb 100644
--- a/scripts/ml.in
+++ b/scripts/ml.in
@@ -400,17 +400,6 @@ case "${thread_safe},${all_libs}" in
         ;;
 esac

-# Set the correct flags if we're to use the MS Visual C runtime.
-use_msvcrt=@USE_MSVCRT@
-if test "${use_msvcrt}" = "yes"
-then
-    MSVCRT_OPTS="-MD"           # Enable linking with the MS Visual C runtime.
-    NODEFAULTLIB_FLAG="-nodefaultlib:libcmt"
-else
-    MSVCRT_OPTS=""
-    NODEFAULTLIB_FLAG=""
-fi
-
 # Use any applicable LTO options
 LTO_OPTS="${LDFLAGS_FOR_LTO}"

@@ -576,8 +565,8 @@ case "${C_COMPILER_TYPE}" in
         ;;
 esac

-LINKER_PRE_FLAGS="${NOLOGO_OPTS} ${MSVCRT_OPTS} ${PRINT_MAP_OPT}
${UNDEF_OPT} ${STRIP_OPTS} ${LTO_OPTS} ${MAYBE_STATIC_OPT}
${ARCH_OPTS} ${SANITIZER_OPTS}"
-LINKER_POST_FLAGS="@LINK_OPT_SEP@ ${MSVC_SETARGV}
${NODEFAULTLIB_FLAG} ${DEBUG_FLAG} ${LIBDIR_OPTS} ${RPATH_OPT_LIST}
${LIBS}"
+LINKER_PRE_FLAGS="${NOLOGO_OPTS} ${PRINT_MAP_OPT} ${UNDEF_OPT}
${STRIP_OPTS} ${LTO_OPTS} ${MAYBE_STATIC_OPT} ${ARCH_OPTS}
${SANITIZER_OPTS}"
+LINKER_POST_FLAGS="@LINK_OPT_SEP@ ${MSVC_SETARGV} ${DEBUG_FLAG}
${LIBDIR_OPTS} ${RPATH_OPT_LIST} ${LIBS}"

 case "${verbose}" in
     true)