--- a/tclconfig/tcl.m4	2018-10-02 11:46:05.621138841 +0200
+++ b/tclconfig/tcl.m4	2018-10-02 11:46:56.041138841 +0200
@@ -1076,7 +1076,7 @@
 	CFLAGS=$hold_cflags])
     AS_IF([test $tcl_cv_cc_visibility_hidden = yes], [
 	AC_DEFINE(MODULE_SCOPE,
-	    [extern __attribute__((__visibility__("hidden")))],
+	    [extern],
 	    [Compiler support for module scope symbols])
 	AC_DEFINE(HAVE_HIDDEN, [1], [Compiler support for module scope symbols])
     ])
@@ -1298,7 +1298,7 @@
 		# mingw gcc mode
 		AC_CHECK_TOOL(RC, windres)
 		CFLAGS_DEBUG="-g"
-		CFLAGS_OPTIMIZE="-O2 -fomit-frame-pointer"
+		CFLAGS_OPTIMIZE=""
 		SHLIB_LD='${CC} -shared'
 		UNSHARED_LIB_SUFFIX='${TCL_TRIM_DOTS}.a'
 		LDFLAGS_CONSOLE="-wl,--subsystem,console ${lflags}"
@@ -1557,7 +1557,7 @@
 	    SHLIB_SUFFIX=".so"
 
 	    # TEA specific:
-	    CFLAGS_OPTIMIZE="-O2 -fomit-frame-pointer"
+	    CFLAGS_OPTIMIZE=""
 
 	    # TEA specific: use LDFLAGS_DEFAULT instead of LDFLAGS
 	    SHLIB_LD='${CC} -shared ${CFLAGS} ${LDFLAGS_DEFAULT}'
@@ -3290,9 +3290,6 @@
 	    hold_cflags=$CFLAGS; CFLAGS="$CFLAGS -pipe"
 	    AC_TRY_COMPILE(,, tcl_cv_cc_pipe=yes, tcl_cv_cc_pipe=no)
 	    CFLAGS=$hold_cflags])
-	if test $tcl_cv_cc_pipe = yes; then
-	    CFLAGS="$CFLAGS -pipe"
-	fi
     fi
 
     #--------------------------------------------------------------------