build: fix compiling with GCC 4.x versions

- silence false positive picky warnings. - avoid "possible noreturn" warnings for standalone tests and examples. - fix to compile without `#pragma GCC diagnostic push` support. - fix "#pragma GCC diagnostic not allowed inside functions". Prerequisite for curl#15975 that needs GCC 4.4 for the latest pre-built CeGCC/mingw32ce toolchain for Windows CE. Cherry-picked from curl#15975 Closes curl#16062
AraHaan · Jan 22, 2025 · 7e814c8 · 7e814c8
1 parent 96843f4
commit 7e814c8
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Showing 13 changed files with 91 additions and 65 deletions.
diff --git a/CMake/PickyWarnings.cmake b/CMake/PickyWarnings.cmake
@@ -236,6 +236,24 @@ if(PICKY_COMPILER)
         list(APPEND _picky "${_ccopt}")
       endif()
     endforeach()
+
+    if(CMAKE_COMPILER_IS_GNUCC)
+      if(CMAKE_C_COMPILER_VERSION VERSION_LESS 4.5)
+        # Avoid false positives
+        list(APPEND _picky "-Wno-shadow")
+        list(APPEND _picky "-Wno-unreachable-code")
+      endif()
+      if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.2 AND CMAKE_C_COMPILER_VERSION VERSION_LESS 4.6)
+        # GCC <4.6 do not support #pragma to suppress warnings locally. Disable them globally instead.
+        list(APPEND _picky "-Wno-overlength-strings")
+      endif()
+      if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.0 AND CMAKE_C_COMPILER_VERSION VERSION_LESS 4.7)
+        list(APPEND _picky "-Wno-missing-field-initializers")  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36750
+      endif()
+      if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.3 AND CMAKE_C_COMPILER_VERSION VERSION_LESS 4.8)
+        list(APPEND _picky "-Wno-type-limits")  # Avoid false positives
+      endif()
+    endif()
   endif()
 endif()
 

diff --git a/docs/examples/cacertinmem.c b/docs/examples/cacertinmem.c
@@ -31,6 +31,10 @@
 #include <curl/curl.h>
 #include <stdio.h>
 
+#if defined(__GNUC__) || defined(__clang__)
+#pragma GCC diagnostic ignored "-Woverlength-strings"
+#endif
+
 static size_t writefunction(void *ptr, size_t size, size_t nmemb, void *stream)
 {
   fwrite(ptr, size, nmemb, (FILE *)stream);
@@ -41,11 +45,6 @@ static CURLcode sslctx_function(CURL *curl, void *sslctx, void *parm)
 {
   CURLcode rv = CURLE_ABORTED_BY_CALLBACK;
 
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Woverlength-strings"
-#endif
-
   /** This example uses two (fake) certificates **/
   static const char mypem[] =
     "-----BEGIN CERTIFICATE-----\n"
@@ -90,10 +89,6 @@ static CURLcode sslctx_function(CURL *curl, void *sslctx, void *parm)
     "Z05phkOTOPu220+DkdRgfks+KzgHVZhepA==\n"
     "-----END CERTIFICATE-----\n";
 
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic pop
-#endif
-
   BIO *cbio = BIO_new_mem_buf(mypem, sizeof(mypem));
   X509_STORE  *cts = SSL_CTX_get_cert_store((SSL_CTX *)sslctx);
   int i;

diff --git a/docs/examples/sendrecv.c b/docs/examples/sendrecv.c
@@ -30,6 +30,19 @@
 #include <string.h>
 #include <curl/curl.h>
 
+/* Avoid warning in FD_SET() with pre-2020 Cygwin/MSYS releases:
+ * warning: conversion to 'long unsigned int' from 'curl_socket_t' {aka 'int'}
+ * may change the sign of the result [-Wsign-conversion]
+ */
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-Wsign-conversion"
+#ifdef __DJGPP__
+#pragma GCC diagnostic ignored "-Warith-conversion"
+#endif
+#elif defined(_MSC_VER)
+#pragma warning(disable:4127)  /* conditional expression is constant */
+#endif
+
 /* Auxiliary function that waits on the socket. */
 static int wait_on_socket(curl_socket_t sockfd, int for_recv, long timeout_ms)
 {
@@ -49,20 +62,6 @@ static int wait_on_socket(curl_socket_t sockfd, int for_recv, long timeout_ms)
   FD_ZERO(&outfd);
   FD_ZERO(&errfd);
 
-/* Avoid this warning with pre-2020 Cygwin/MSYS releases:
- * warning: conversion to 'long unsigned int' from 'curl_socket_t' {aka 'int'}
- * may change the sign of the result [-Wsign-conversion]
- */
-#if defined(__GNUC__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wsign-conversion"
-#if defined(__DJGPP__)
-#pragma GCC diagnostic ignored "-Warith-conversion"
-#endif
-#elif defined(_MSC_VER)
-#pragma warning(push)
-#pragma warning(disable:4127)  /* conditional expression is constant */
-#endif
   FD_SET(sockfd, &errfd); /* always check for error */
 
   if(for_recv) {
@@ -71,11 +70,6 @@ static int wait_on_socket(curl_socket_t sockfd, int for_recv, long timeout_ms)
   else {
     FD_SET(sockfd, &outfd);
   }
-#if defined(__GNUC__)
-#pragma GCC diagnostic pop
-#elif defined(_MSC_VER)
-#pragma warning(pop)
-#endif
 
   /* select() returns the number of signalled sockets or -1 */
   res = select((int)sockfd + 1, &infd, &outfd, &errfd, &tv);

diff --git a/docs/examples/usercertinmem.c b/docs/examples/usercertinmem.c
@@ -41,6 +41,10 @@
 #include <curl/curl.h>
 #include <stdio.h>
 
+#if defined(__GNUC__) || defined(__clang__)
+#pragma GCC diagnostic ignored "-Woverlength-strings"
+#endif
+
 static size_t writefunction(void *ptr, size_t size, size_t nmemb, void *stream)
 {
   fwrite(ptr, size, nmemb, stream);
@@ -55,11 +59,6 @@ static CURLcode sslctx_function(CURL *curl, void *sslctx, void *parm)
   RSA *rsa = NULL;
   int ret;
 
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Woverlength-strings"
-#endif
-
   const char *mypem = /* www.cacert.org */
     "-----BEGIN CERTIFICATE-----\n"\
     "MIIHPTCCBSWgAwIBAgIBADANBgkqhkiG9w0BAQQFADB5MRAwDgYDVQQKEwdSb290\n"\
@@ -124,10 +123,6 @@ static CURLcode sslctx_function(CURL *curl, void *sslctx, void *parm)
     "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"\
     "-----END RSA PRIVATE KEY-----\n";
 
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic pop
-#endif
-
   (void)curl; /* avoid warnings */
   (void)parm; /* avoid warnings */
 

diff --git a/m4/curl-compilers.m4 b/m4/curl-compilers.m4
@@ -1113,6 +1113,23 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
             fi
           fi
         fi
+        if test "$compiler_num" -lt "405"; then
+          dnl Avoid false positives
+          tmp_CFLAGS="$tmp_CFLAGS -Wno-shadow"
+          tmp_CFLAGS="$tmp_CFLAGS -Wno-unreachable-code"
+        fi
+        if test "$compiler_num" -ge "402" -a "$compiler_num" -lt "406"; then
+          dnl GCC <4.6 do not support #pragma to suppress warnings locally. Disable globally instead.
+          tmp_CFLAGS="$tmp_CFLAGS -Wno-overlength-strings"
+        fi
+        if test "$compiler_num" -ge "400" -a "$compiler_num" -lt "407"; then
+          dnl https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84685
+          tmp_CFLAGS="$tmp_CFLAGS -Wno-missing-field-initializers"
+        fi
+        if test "$compiler_num" -ge "403" -a "$compiler_num" -lt "408"; then
+          dnl Avoid false positives
+          tmp_CFLAGS="$tmp_CFLAGS -Wno-type-limits"
+        fi
         ;;
         #
       HP_UX_C)

diff --git a/tests/http/clients/h2-pausing.c b/tests/http/clients/h2-pausing.c
@@ -140,11 +140,11 @@ static int debug_cb(CURL *handle, curl_infotype type,
   return 0;
 }
 
-static int err(void)
-{
-  fprintf(stderr, "something unexpected went wrong - bailing out!\n");
-  exit(2);
-}
+#define ERR()                                                             \
+  do {                                                                    \
+    fprintf(stderr, "something unexpected went wrong - bailing out!\n");  \
+    exit(2);                                                              \
+  } while(0)
 
 static void usage(const char *msg)
 {
@@ -292,24 +292,24 @@ int main(int argc, char *argv[])
       curl_easy_setopt(handles[i].h, CURLOPT_RESOLVE, resolve) != CURLE_OK ||
       curl_easy_setopt(handles[i].h, CURLOPT_PIPEWAIT, 1L) ||
       curl_easy_setopt(handles[i].h, CURLOPT_URL, url) != CURLE_OK) {
-      err();
+      ERR();
     }
     curl_easy_setopt(handles[i].h, CURLOPT_HTTP_VERSION, (long)http_version);
   }
 
   multi_handle = curl_multi_init();
   if(!multi_handle)
-    err();
+    ERR();
 
   for(i = 0; i < HANDLECOUNT; i++) {
     if(curl_multi_add_handle(multi_handle, handles[i].h) != CURLM_OK)
-      err();
+      ERR();
   }
 
   for(rounds = 0;; rounds++) {
     fprintf(stderr, "INFO: multi_perform round %d\n", rounds);
     if(curl_multi_perform(multi_handle, &still_running) != CURLM_OK)
-      err();
+      ERR();
 
     if(!still_running) {
       int as_expected = 1;
@@ -343,7 +343,7 @@ int main(int argc, char *argv[])
     }
 
     if(curl_multi_poll(multi_handle, NULL, 0, 100, &numfds) != CURLM_OK)
-      err();
+      ERR();
 
     /* !checksrc! disable EQUALSNULL 1 */
     while((msg = curl_multi_info_read(multi_handle, &msgs_left)) != NULL) {

diff --git a/tests/http/clients/upload-pausing.c b/tests/http/clients/upload-pausing.c
@@ -180,11 +180,11 @@ static int progress_callback(void *clientp,
   return 0;
 }
 
-static int err(void)
-{
-  fprintf(stderr, "something unexpected went wrong - bailing out!\n");
-  exit(2);
-}
+#define ERR()                                                             \
+  do {                                                                    \
+    fprintf(stderr, "something unexpected went wrong - bailing out!\n");  \
+    exit(2);                                                              \
+  } while(0)
 
 static void usage(const char *msg)
 {
@@ -294,7 +294,7 @@ int main(int argc, char *argv[])
      curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, debug_cb)
      != CURLE_OK ||
      curl_easy_setopt(curl, CURLOPT_RESOLVE, resolve) != CURLE_OK)
-    err();
+    ERR();
 
   curl_easy_setopt(curl, CURLOPT_URL, url);
   curl_easy_setopt(curl, CURLOPT_HTTP_VERSION, http_version);

diff --git a/tests/libtest/lib557.c b/tests/libtest/lib557.c
@@ -37,7 +37,7 @@
 
 #include "memdebug.h"
 
-#if defined(__GNUC__) || defined(__clang__)
+#if defined(CURL_GNUC_DIAG) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wformat"
 #pragma GCC diagnostic ignored "-Wformat-extra-args"
@@ -1601,6 +1601,6 @@ CURLcode test(char *URL)
     return CURLE_OK;
 }
 
-#if defined(__GNUC__) || defined(__clang__)
+#if defined(CURL_GNUC_DIAG) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
diff --git a/tests/libtest/test.h b/tests/libtest/test.h
@@ -44,6 +44,13 @@
 
 #include "curl_printf.h"
 
+/* GCC <4.6 does not support '#pragma GCC diagnostic push' and
+   does not support 'pragma GCC diagnostic' inside functions. */
+#if (defined(__GNUC__) && \
+  ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 6))))
+#define CURL_GNUC_DIAG
+#endif
+
 #ifdef _WIN32
 #define sleep(sec) Sleep((sec)*1000)
 #endif

diff --git a/tests/unit/unit1398.c b/tests/unit/unit1398.c
@@ -23,7 +23,7 @@
  ***************************************************************************/
 #include "curlcheck.h"
 
-#if defined(__GNUC__) || defined(__clang__)
+#if defined(CURL_GNUC_DIAG) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wformat"
 #endif
@@ -186,6 +186,6 @@ fail_unless(rc == 128, "return code should be 128");
 
 UNITTEST_STOP
 
-#if defined(__GNUC__) || defined(__clang__)
+#if defined(CURL_GNUC_DIAG) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
diff --git a/tests/unit/unit1652.c b/tests/unit/unit1652.c
@@ -92,7 +92,7 @@ static int verify(const char *info, const char *two)
 
 UNITTEST_START
 
-#if defined(__GNUC__) && !defined(__clang__)
+#if defined(CURL_GNUC_DIAG) && !defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wformat"
 #pragma GCC diagnostic ignored "-Wformat-zero-length"
@@ -146,7 +146,7 @@ Curl_infof(testdata, "%s", input);
 fail_unless(strlen(output) == 2051, "Truncation of infof input 3");
 fail_unless(output[sizeof(output) - 1] == '\0', "Truncation of infof input 3");
 
-#if defined(__GNUC__) && !defined(__clang__)
+#if defined(CURL_GNUC_DIAG) && !defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
 

diff --git a/tests/unit/unit2604.c b/tests/unit/unit2604.c
@@ -46,7 +46,7 @@ struct set {
 UNITTEST_START
 #ifdef USE_SSH
 {
-#if defined(__GNUC__) || defined(__clang__)
+#if defined(CURL_GNUC_DIAG) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Woverlength-strings"
 #endif
@@ -78,7 +78,7 @@ UNITTEST_START
     { NULL, NULL, NULL, NULL, CURLE_OK }
   };
 
-#if defined(__GNUC__) || defined(__clang__)
+#if defined(CURL_GNUC_DIAG) || defined(__clang__)
 #pragma GCC diagnostic warning "-Woverlength-strings"
 #endif
 
@@ -114,7 +114,7 @@ UNITTEST_START
 
   free((void *)list[0].cp);
 }
-#if defined(__GNUC__) || defined(__clang__)
+#if defined(CURL_GNUC_DIAG) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif
 

diff --git a/tests/unit/unit3200.c b/tests/unit/unit3200.c
@@ -49,7 +49,7 @@ static CURLcode unit_stop(void)
   return CURLE_OK;
 }
 
-#if defined(__GNUC__) || defined(__clang__)
+#if defined(CURL_GNUC_DIAG) || defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Woverlength-strings"
 #endif
@@ -80,7 +80,7 @@ static const char *filecontents[] = {
   "LINE1\x1aTEST"
 };
 
-#if defined(__GNUC__) || defined(__clang__)
+#if defined(CURL_GNUC_DIAG) || defined(__clang__)
 #pragma GCC diagnostic warning "-Woverlength-strings"
 #endif
 
@@ -175,7 +175,7 @@ UNITTEST_START
   return (CURLcode)rc;
 UNITTEST_STOP
 
-#if defined(__GNUC__) || defined(__clang__)
+#if defined(CURL_GNUC_DIAG) || defined(__clang__)
 #pragma GCC diagnostic pop
 #endif