[mono] Propagate -Werror properly, fix warning (#41996)

Author: CoffeeFlux

src/mono/Makefile.am

@@ -1,7 +1,5 @@
 ACLOCAL_AMFLAGS = -I m4
 
-AM_CFLAGS = $(WERROR_CFLAGS)
-
 SUBDIRS = @MONO_SUBDIRS@
 noinst_SUBDIRS = @MONO_NOINST_SUBDIRS@
 DIST_SUBDIRS = $(SUBDIRS) m4

src/mono/configure.ac

@@ -1034,9 +1034,8 @@ AM_CONDITIONAL(NINJA, test x$enable_ninja = xyes -a x$HAVE_NINJA != xno)
 
 AC_ARG_ENABLE(werror, [  --enable-werror Pass -Werror to the C compiler], werror_flag=$enableval, werror_flag=no)
 if test x$werror_flag = xyes; then
-	WERROR_CFLAGS="-Werror"
+	SHARED_CFLAGS="$SHARED_CFLAGS -Werror"
 fi
-AC_SUBST([WERROR_CFLAGS])
 AC_SUBST([SHARED_CFLAGS])
 
 GLIB_CFLAGS='-I$(top_srcdir)/mono/eglib -I$(top_builddir)/mono/eglib'

src/mono/mono/eglib/Makefile.am

@@ -6,7 +6,7 @@ SUBDIRS = . test
 
 noinst_LTLIBRARIES = libeglib.la
 
-AM_CFLAGS = $(WERROR_CFLAGS)
+AM_CFLAGS = $(SHARED_CFLAGS)
 
 win_files  = \
 	eglib-config.hw \

src/mono/mono/metadata/cominterop.c

@@ -4155,6 +4155,7 @@ ves_icall_System_Runtime_InteropServices_Marshal_QueryInterfaceInternal (MonoIUn
 #endif /* HOST_WIN32 */
 #endif /* DISABLE_COM */
 
+#ifndef ENABLE_NETCORE
 MonoStringHandle
 ves_icall_System_Runtime_InteropServices_Marshal_PtrToStringBSTR (mono_bstr_const ptr, MonoError *error)
 {
@@ -4164,6 +4165,7 @@ ves_icall_System_Runtime_InteropServices_Marshal_PtrToStringBSTR (mono_bstr_cons
 	}
 	return mono_string_from_bstr_checked (ptr, error);
 }
+#endif
 
 mono_bstr
 ves_icall_System_Runtime_InteropServices_Marshal_BufferToBSTR (const gunichar2* ptr, int len)