configure: remove use of RETSIGTYPE

This was previously defined by the obsolete AC_TYPE_SIGNAL macro,
which was removed in 2682e5f5. The deprecation text says

> Your code may safely assume C89 semantics that RETSIGTYPE is void.

So, remove it and just use void instead.

Closes #6861

14 files changed, 7 insertions, 44 deletions

diff --git a/lib/Makefile.netware b/lib/Makefile.netware
index 10b77f8ff..863bde022 100644
--- a/lib/Makefile.netware
+++ b/lib/Makefile.netware
@@ -5,8 +5,8 @@
 #                            | (__| |_| |  _ <| |___
 #                             \___|\___/|_| \_\_____|
 #
-# Copyright (C) 2004 - 2015, Guenter Knauf
-# Copyright (C) 2001 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+# Copyright (C) 2004 - 2015, 2021, Guenter Knauf
+# Copyright (C) 2001 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
 #
 # This software is licensed as described in the file COPYING, which
 # you should have received as part of this distribution. The terms
@@ -599,7 +599,6 @@ endif
 	@echo $(DL)#define HAVE_UTIME 1$(DL) >> $@
 	@echo $(DL)#define HAVE_UTIME_H 1$(DL) >> $@
 	@echo $(DL)#define HAVE_WRITEV 1$(DL) >> $@
-	@echo $(DL)#define RETSIGTYPE void$(DL) >> $@
 	@echo $(DL)#define SIZEOF_INT 4$(DL) >> $@
 	@echo $(DL)#define SIZEOF_SHORT 2$(DL) >> $@
 	@echo $(DL)#define SIZEOF_STRUCT_IN_ADDR 4$(DL) >> $@
diff --git a/lib/config-amigaos.h b/lib/config-amigaos.h
index 3c9d76ef3..381bf302c 100644
--- a/lib/config-amigaos.h
+++ b/lib/config-amigaos.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -103,7 +103,6 @@
 #define PACKAGE_VERSION "-"
 #define CURL_CA_BUNDLE "s:curl-ca-bundle.crt"
 
-#define RETSIGTYPE void
 #define SELECT_TYPE_ARG1 int
 #define SELECT_TYPE_ARG234 (fd_set *)
 #define SELECT_TYPE_ARG5 (struct timeval *)
diff --git a/lib/config-dos.h b/lib/config-dos.h
index 50816ac75..0fb98e385 100644
--- a/lib/config-dos.h
+++ b/lib/config-dos.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -84,7 +84,6 @@
 
 #define NEED_MALLOC_H          1
 
-#define RETSIGTYPE             void
 #define SIZEOF_INT             4
 #define SIZEOF_LONG            4
 #define SIZEOF_LONG_DOUBLE     16
diff --git a/lib/config-mac.h b/lib/config-mac.h
index 4e610562f..163686ec9 100644
--- a/lib/config-mac.h
+++ b/lib/config-mac.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -81,8 +81,6 @@
 #define HAVE_IOCTL              1
 #define HAVE_IOCTL_FIONBIO      1
 
-#define RETSIGTYPE void
-
 #define SIZEOF_INT              4
 #define SIZEOF_SHORT            2
 #define SIZEOF_SIZE_T           4
diff --git a/lib/config-os400.h b/lib/config-os400.h
index 67fbc41d8..b5a9823fd 100644
--- a/lib/config-os400.h
+++ b/lib/config-os400.h
@@ -376,9 +376,6 @@
 /* Name of package */
 #undef PACKAGE
 
-/* Define as the return type of signal handlers (`int' or `void'). */
-#define RETSIGTYPE void
-
 /* The size of `int', as computed by sizeof. */
 #define SIZEOF_INT              4
 
diff --git a/lib/config-plan9.h b/lib/config-plan9.h
index fc19c5f03..ecfc27372 100644
--- a/lib/config-plan9.h
+++ b/lib/config-plan9.h
@@ -40,8 +40,6 @@
 #define RANDOM_FILE "/dev/random"
 #define VERSION "0.0.0" /* TODO */
 
-#define RETSIGTYPE void
-
 #define STDC_HEADERS 1
 
 #ifdef _BITS64
diff --git a/lib/config-riscos.h b/lib/config-riscos.h
index 43b1deb6d..2dc3c6631 100644
--- a/lib/config-riscos.h
+++ b/lib/config-riscos.h
@@ -353,9 +353,6 @@
 /* Name of package */
 #undef PACKAGE
 
-/* Define as the return type of signal handlers (`int' or `void'). */
-#define RETSIGTYPE void
-
 /* The size of `int', as computed by sizeof. */
 #define SIZEOF_INT 4
 
diff --git a/lib/config-tpf.h b/lib/config-tpf.h
index 4f8a07e9b..3fdb8924c 100644
--- a/lib/config-tpf.h
+++ b/lib/config-tpf.h
@@ -578,9 +578,6 @@
 /* a suitable file to read random data from */
 /* #undef RANDOM_FILE */
 
-/* Define as the return type of signal handlers (`int' or `void'). */
-#define RETSIGTYPE void
-
 /* Define to the type of arg 1 for `select'. */
 #define SELECT_TYPE_ARG1 int
 
diff --git a/lib/config-vxworks.h b/lib/config-vxworks.h
index f81195285..c4925bb22 100644
--- a/lib/config-vxworks.h
+++ b/lib/config-vxworks.h
@@ -769,9 +769,6 @@
 /* Define to the function return type for recv. */
 #define RECV_TYPE_RETV int
 
-/* Define as the return type of signal handlers (`int' or `void'). */
-#define RETSIGTYPE void
-
 /* Define to the type qualifier of arg 5 for select. */
 #define SELECT_QUAL_ARG5
 
diff --git a/lib/config-win32.h b/lib/config-win32.h
index 0817ec5b1..2e060f95c 100644
--- a/lib/config-win32.h
+++ b/lib/config-win32.h
@@ -362,9 +362,6 @@
 /* Define if in_addr_t is not an available 'typedefed' type. */
 #define in_addr_t unsigned long
 
-/* Define to the return type of signal handlers (int or void). */
-#define RETSIGTYPE void
-
 /* Define if ssize_t is not an available 'typedefed' type. */
 #ifndef _SSIZE_T_DEFINED
 #  if (defined(__WATCOMC__) && (__WATCOMC__ >= 1240)) || \
diff --git a/lib/config-win32ce.h b/lib/config-win32ce.h
index 7f59fd562..fb29e088f 100644
--- a/lib/config-win32ce.h
+++ b/lib/config-win32ce.h
@@ -307,9 +307,6 @@
 /* Define this if in_addr_t is not an available 'typedefed' type */
 #define in_addr_t unsigned long
 
-/* Define as the return type of signal handlers (int or void).  */
-#define RETSIGTYPE void
-
 /* Define ssize_t if it is not an available 'typedefed' type */
 #if (defined(__WATCOMC__) && (__WATCOMC__ >= 1240)) || defined(__POCC__)
 #elif defined(_WIN64)
diff --git a/lib/curl_config.h.cmake b/lib/curl_config.h.cmake
index fc1857ebb..d64c89ce3 100644
--- a/lib/curl_config.h.cmake
+++ b/lib/curl_config.h.cmake
@@ -876,9 +876,6 @@
 /* Define to the function return type for recv. */
 #cmakedefine RECV_TYPE_RETV ${RECV_TYPE_RETV}
 
-/* Define as the return type of signal handlers (`int' or `void'). */
-#cmakedefine RETSIGTYPE ${RETSIGTYPE}
-
 /* Define to the type qualifier of arg 5 for select. */
 #cmakedefine SELECT_QUAL_ARG5 ${SELECT_QUAL_ARG5}
 
diff --git a/lib/curl_setup_once.h b/lib/curl_setup_once.h
index ef60bc7ae..adf1e11f8 100644
--- a/lib/curl_setup_once.h
+++ b/lib/curl_setup_once.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -351,15 +351,6 @@ typedef int sig_atomic_t;
 
 
 /*
- * Default return type for signal handlers.
- */
-
-#ifndef RETSIGTYPE
-#define RETSIGTYPE void
-#endif
-
-
-/*
  * Macro used to include code only in debug builds.
  */
 
diff --git a/lib/hostip.c b/lib/hostip.c
index 34fb7db65..05c09f683 100644
--- a/lib/hostip.c
+++ b/lib/hostip.c
@@ -631,7 +631,7 @@ enum resolve_t Curl_resolv(struct Curl_easy *data,
  * within a signal handler which is nonportable and could lead to problems.
  */
 static
-RETSIGTYPE alarmfunc(int sig)
+void alarmfunc(int sig)
 {
   /* this is for "-ansi -Wall -pedantic" to stop complaining!   (rabe) */
   (void)sig;