Configure changes for HAS_NON_INT_BITFIELDS

This probe has been available without my realizing it had been merged. Some compilers, chiefly IBM, use only integer-size bitfields, warning when presented with other-sized ones. Allowing other-sized fields is an extension to the C standard. These warnings don't affect the correctness of the code generated, but very many are generated per run, potentially overwhelming the reader into not noticing warnings that are important.
Perl · Jun 6, 2021 · 8dafde0 · 8dafde0
1 parent cd0c6ec
commit 8dafde0
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Showing 14 changed files with 61 additions and 4 deletions.
diff --git a/Configure b/Configure
@@ -394,6 +394,7 @@ d_attribute_unused=''
 d_attribute_warn_unused_result=''
 d_printf_format_null=''
 d_backtrace=''
+d_non_int_bitfields=''
 d_builtin_choose_expr=''
 d_builtin_expect=''
 d_builtin_add_overflow=''
@@ -16541,6 +16542,37 @@ eval $inhdr
 set nl_langinfo d_nl_langinfo
 eval $inlibc
 
+: Look for non 'int'-sized bitfields
+case "$d_non_int_bitfields" in
+'')
+echo " " >&4
+echo "Checking whether your compiler can handle struct bitfields that aren't 'int' or 'unsigned int' ..." >&4
+$cat >try.c <<'EOCP'
+#include <stdio.h>
+struct foo {
+    unsigned char byte:1;
+    unsigned short halfword:1;
+} bar;
+EOCP
+if $cc $ccflags -c try.c >try.out 2>&1 ; then
+	if $compiler_warning try.out >/dev/null 2>&1; then
+		echo "Your C compiler doesn't support struct bitfields that aren't 'int' or 'unsigned int'." >&4
+		val="$undef"
+	else
+		echo "Your C compiler supports struct bitfields besides 'int' and 'unsigned int'." >&4
+		val="$define"
+	fi
+else
+	echo "Your C compiler doesn't seem to understand struct bitfields that aren't 'int' or 'unsigned int' at all." >&4
+	val="$undef"
+fi
+;;
+*) val="$d_non_int_bitfields" ;;
+esac
+set d_non_int_bitfields
+eval $setvar
+$rm_try
+
 : see if this is a quadmath.h system
 set quadmath.h i_quadmath
 eval $inhdr
@@ -24527,6 +24559,7 @@ d_nextafter='$d_nextafter'
 d_nexttoward='$d_nexttoward'
 d_nice='$d_nice'
 d_nl_langinfo='$d_nl_langinfo'
+d_non_int_bitfields='$d_non_int_bitfields'
 d_nv_preserves_uv='$d_nv_preserves_uv'
 d_nv_zero_is_allbits_zero='$d_nv_zero_is_allbits_zero'
 d_off64_t='$d_off64_t'

diff --git a/Cross/config.sh-arm-linux b/Cross/config.sh-arm-linux
@@ -418,6 +418,7 @@ d_nextafter='undef'
 d_nexttoward='undef'
 d_nice='define'
 d_nl_langinfo='define'
+d_non_int_bitfields='define'
 d_nv_preserves_uv='define'
 d_nv_zero_is_allbits_zero='undef'
 d_off64_t='undef'

diff --git a/Cross/config.sh-arm-linux-n770 b/Cross/config.sh-arm-linux-n770
@@ -417,6 +417,7 @@ d_nextafter='undef'
 d_nexttoward='undef'
 d_nice='define'
 d_nl_langinfo='define'
+d_non_int_bitfields='define'
 d_nv_preserves_uv='define'
 d_nv_zero_is_allbits_zero='undef'
 d_off64_t='undef'

diff --git a/NetWare/config.wc b/NetWare/config.wc
@@ -407,6 +407,7 @@ d_nextafter='undef'
 d_nexttoward='undef'
 d_nice='undef'
 d_nl_langinfo='undef'
+d_non_int_bitfields='define'
 d_nv_preserves_uv='define'
 d_nv_zero_is_allbits_zero='undef'
 d_off64_t='undef'

diff --git a/Porting/config.sh b/Porting/config.sh
@@ -436,6 +436,7 @@ d_nextafter='define'
 d_nexttoward='define'
 d_nice='define'
 d_nl_langinfo='define'
+d_non_int_bitfields='define'
 d_nv_preserves_uv='define'
 d_nv_zero_is_allbits_zero='undef'
 d_off64_t='define'

diff --git a/config_h.SH b/config_h.SH
@@ -2339,6 +2339,13 @@ sed <<!GROK!THIS! >$CONFIG_H -e 's!^#undef\(.*/\)\*!/\*#define\1 \*!' -e 's!^#un
  */
 #$d_atanh HAS_ATANH		/**/
 
+/* HAS_NON_INT_BITFIELDS:
+ *	This symbol, if defined, indicates that the C compiler accepts, without
+ *	error or warning, struct bitfields that are declared with sizes other
+ *	than plain 'int'; for example 'unsigned char' is accepted.
+ */
+#$d_non_int_bitfields HAS_NON_INT_BITFIELDS	/**/
+
 /* HAS_BUILTIN_CHOOSE_EXPR:
  *	Can we handle GCC builtin for compile-time ternary-like expressions
  */

diff --git a/configure.com b/configure.com
@@ -5610,6 +5610,7 @@ $ d_mbstowcs="define"
 $ d_mbtowc="define"
 $ d_mktime="define"
 $ d_nl_langinfo="define"
+$ d_non_int_bitfields="define"
 $ d_setlocale="define"
 $ d_setlocale_accepts_any_locale_name="undef"
 $ d_stdiobase="define"
@@ -6399,6 +6400,7 @@ $ WC "d_nextafter='" + d_nextafter + "'"
 $ WC "d_nexttoward='" + d_nexttoward + "'"
 $ WC "d_nice='define'"
 $ WC "d_nl_langinfo='" + d_nl_langinfo + "'"
+$ WC "d_non_int_bitfields='define'"
 $ WC "d_getenv_preserves_other_thread='" + d_getenv_preserves_other_thread + "'"
 $ WC "d_nv_preserves_uv='" + d_nv_preserves_uv + "'"
 $ WC "nv_overflows_integers_at='" + nv_overflows_integers_at + "'"

diff --git a/metaconfig.h b/metaconfig.h
@@ -13,7 +13,6 @@
  * Symbols should only be here temporarily. Once they are actually used,
  * they should be removed from here.
  *
- * HAS_WCRTOMB
- * GETENV_PRESERVES_OTHER_THREAD
+ * HAS_NON_INT_BITFIELDS
  *
  */
diff --git a/plan9/config_sh.sample b/plan9/config_sh.sample
@@ -418,6 +418,7 @@ d_nextafter='undef'
 d_nexttoward='undef'
 d_nice='undef'
 d_nl_langinfo='undef'
+d_non_int_bitfields='define'
 d_nv_preserves_uv='undef'
 d_nv_zero_is_allbits_zero='undef'
 d_off64_t='undef'

diff --git a/uconfig.h b/uconfig.h
@@ -2304,6 +2304,13 @@
  */
 /*#define HAS_ATANH		/ **/
 
+/* HAS_NON_INT_BITFIELDS:
+ *	This symbol, if defined, indicates that the C compiler accepts, without
+ *	error or warning, struct bitfields that are declared with sizes other
+ *	than plain 'int'; for example 'unsigned char' is accepted.
+ */
+#define HAS_NON_INT_BITFIELDS	/**/
+
 /* HAS_BUILTIN_CHOOSE_EXPR:
  *	Can we handle GCC builtin for compile-time ternary-like expressions
  */
@@ -5282,6 +5289,6 @@
 #endif
 
 /* Generated from:
- * 6edd641b187b02d0daa8cb53f5d22f2dcca115a0d3e744f51b0292d2db484ca5 config_h.SH
- * a0fa823df68d3b6a854579e3727e8d354614ad995d17f68b691399261825c2d3 uconfig.sh
+ * dac70e6e1bbb594cb13128b2271cfd83bc32d4cb1d14179edc6100597299d0bf config_h.SH
+ * bad73e58d466bfe6befab92731c4d075d5d439b45fd11c20585b3514865093a8 uconfig.sh
  * ex: set ro: */
diff --git a/uconfig.sh b/uconfig.sh
@@ -358,6 +358,7 @@ d_nextafter='undef'
 d_nexttoward='undef'
 d_nice='undef'
 d_nl_langinfo='undef'
+d_non_int_bitfields='define'
 d_nv_preserves_uv='undef'
 d_nv_zero_is_allbits_zero='undef'
 d_off64_t='undef'

diff --git a/uconfig64.sh b/uconfig64.sh
@@ -358,6 +358,7 @@ d_nextafter='undef'
 d_nexttoward='undef'
 d_nice='undef'
 d_nl_langinfo='undef'
+d_non_int_bitfields='define'
 d_nv_preserves_uv='undef'
 d_nv_zero_is_allbits_zero='undef'
 d_off64_t='undef'

diff --git a/win32/config.gc b/win32/config.gc
@@ -407,6 +407,7 @@ d_nextafter='define'
 d_nexttoward='define'
 d_nice='undef'
 d_nl_langinfo='undef'
+d_non_int_bitfields='define'
 d_nv_preserves_uv='define'
 d_nv_zero_is_allbits_zero='define'
 d_off64_t='undef'

diff --git a/win32/config.vc b/win32/config.vc
@@ -407,6 +407,7 @@ d_nextafter='undef'
 d_nexttoward='undef'
 d_nice='undef'
 d_nl_langinfo='undef'
+d_non_int_bitfields='define'
 d_nv_preserves_uv='define'
 d_nv_zero_is_allbits_zero='define'
 d_off64_t='undef'