>From commit 79444c9294, ("utf8: handle systems that don't write BOM for
UTF-16", 2019-02-12), we're supporting those systems with iconv that
omits BOM with:
make ICONV_OMITS_BOM=Yes
However, typing the flag all the time is cumbersome and error-prone.
Add a check into configure script to detect this flag automatically.
Signed-off-by: Doan Tran Cong Danh <congdanhqx@xxxxxxxxx>
---
configure.ac | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 49 insertions(+)
diff --git a/configure.ac b/configure.ac
index a43b476402..ecba7e6e51 100644
--- a/configure.ac
+++ b/configure.ac
@@ -844,12 +844,61 @@ AC_MSG_CHECKING([for old iconv()])
AC_COMPILE_IFELSE([OLDICONVTEST_SRC],
[AC_MSG_RESULT([no])],
[AC_MSG_RESULT([yes])
+ AC_DEFINE(HAVE_OLD_ICONV, 1)
OLD_ICONV=UnfortunatelyYes])
GIT_UNSTASH_FLAGS($ICONVDIR)
GIT_CONF_SUBST([OLD_ICONV])
+#
+# Define ICONV_OMITS_BOM if you are on a system which
+# iconv omits bom for utf-{16,32}
+if test -z "$NO_ICONV"; then
+AC_CACHE_CHECK([whether iconv omits bom for utf-16 and utf-32],
+ [ac_cv_iconv_omits_bom],
+[
+old_LIBS="$LIBS"
+if test -n "$NEEDS_LIBICONV"; then
+ LIBS="$LIBS -liconv"
+fi
+
+AC_RUN_IFELSE(
+ [AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT
+ #include <iconv.h>
+ #ifdef HAVE_OLD_ICONV
+ typedef const char *iconv_ibp;
+ #else
+ typedef char *iconv_ibp;
+ #endif
+ ],
+ [[
+ int v;
+ iconv_t conv;
+ char in[] = "a"; iconv_ibp pin = in;
+ char out[20] = ""; char *pout = out;
+ size_t isz = sizeof in;
+ size_t osz = sizeof out;
+
+ conv = iconv_open("UTF-16", "UTF-8");
+ iconv(conv, &pin, &isz, &pout, &osz);
+ iconv_close(conv);
+ v = (unsigned char)(out[0]) + (unsigned char)(out[1]);
+ return v != 0xfe + 0xff;
+ ]])],
+ [ac_cv_iconv_omits_bom=no],
+ [ac_cv_iconv_omits_bom=yes])
+
+LIBS="$old_LIBS"
+])
+if test "x$ac_cv_iconv_omits_bom" = xyes; then
+ ICONV_OMITS_BOM=Yes
+else
+ ICONV_OMITS_BOM=
+fi
+GIT_CONF_SUBST([ICONV_OMITS_BOM])
+fi
+
## Checks for typedefs, structures, and compiler characteristics.
AC_MSG_NOTICE([CHECKS for typedefs, structures, and compiler characteristics])
#
--
2.24.0.8.g36796e2b67
