build: add picky compiler warning flags for gcc 6 and 7

6 files changed, 25 insertions, 5 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index 69bb6c002..69bb6c002 100755..100644
--- a/acinclude.m4
+++ b/acinclude.m4
diff --git a/lib/curl_addrinfo.c b/lib/curl_addrinfo.c
index 95a3f1050..01775f704 100644
--- a/lib/curl_addrinfo.c
+++ b/lib/curl_addrinfo.c
@@ -345,7 +345,7 @@ Curl_he2ai(const struct hostent *he, int port)
       addr = (void *)ai->ai_addr; /* storage area for this info */
 
       memcpy(&addr->sin_addr, curr, sizeof(struct in_addr));
-      addr->sin_family = (unsigned short)(he->h_addrtype);
+      addr->sin_family = (sa_family_t)(he->h_addrtype);
       addr->sin_port = htons((unsigned short)port);
       break;
 
@@ -354,7 +354,7 @@ Curl_he2ai(const struct hostent *he, int port)
       addr6 = (void *)ai->ai_addr; /* storage area for this info */
 
       memcpy(&addr6->sin6_addr, curr, sizeof(struct in6_addr));
-      addr6->sin6_family = (unsigned short)(he->h_addrtype);
+      addr6->sin6_family = (sa_family_t)(he->h_addrtype);
       addr6->sin6_port = htons((unsigned short)port);
       break;
 #endif
diff --git a/lib/mime.c b/lib/mime.c
index 89819a935..ce56d7873 100644
--- a/lib/mime.c
+++ b/lib/mime.c
@@ -1193,7 +1193,10 @@ CURLcode Curl_mime_duppart(curl_mimepart *dst, const curl_mimepart *src)
   }
 
   /* Duplicate other fields. */
-  dst->encoder = src->encoder;
+  if(dst != NULL)
+    dst->encoder = src->encoder;
+  else
+    res = CURLE_WRITE_ERROR;
   if(!res)
     res = curl_mime_type(dst, src->mimetype);
   if(!res)
diff --git a/lib/tftp.c b/lib/tftp.c
index 20dc60040..7fd7b3751 100644
--- a/lib/tftp.c
+++ b/lib/tftp.c
@@ -1010,7 +1010,7 @@ static CURLcode tftp_connect(struct connectdata *conn, bool *done)
   state->requested_blksize = blksize;
 
   ((struct sockaddr *)&state->local_addr)->sa_family =
-    (unsigned short)(conn->ip_addr->ai_family);
+    (sa_family_t)(conn->ip_addr->ai_family);
 
   tftp_set_timeouts(state);
 
diff --git a/lib/timeval.c b/lib/timeval.c
index d11b95197..f4bf83531 100644
--- a/lib/timeval.c
+++ b/lib/timeval.c
@@ -110,7 +110,7 @@ struct curltime Curl_now(void)
   usecs /= 1000;
 
   cnow.tv_sec = usecs / 1000000;
-  cnow.tv_usec = usecs % 1000000;
+  cnow.tv_usec = (int)(usecs % 1000000);
 
   return cnow;
 }
diff --git a/m4/curl-compilers.m4 b/m4/curl-compilers.m4
index 422946e26..20bdbd706 100644
--- a/m4/curl-compilers.m4
+++ b/m4/curl-compilers.m4
@@ -1044,6 +1044,23 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
             tmp_CFLAGS="$tmp_CFLAGS -Wdouble-promotion"
           fi
           #
+          dnl Only gcc 6 or later
+          if test "$compiler_num" -ge "600"; then
+            tmp_CFLAGS="$tmp_CFLAGS -Wshift-negative-value"
+            tmp_CFLAGS="$tmp_CFLAGS -Wshift-overflow=2"
+            tmp_CFLAGS="$tmp_CFLAGS -Wnull-dereference"
+            tmp_CFLAGS="$tmp_CFLAGS -Wduplicated-cond"
+          fi
+          #
+          dnl Only gcc 7 or later
+          if test "$compiler_num" -ge "700"; then
+            tmp_CFLAGS="$tmp_CFLAGS -Wduplicated-branches"
+            tmp_CFLAGS="$tmp_CFLAGS -Wrestrict"
+            tmp_CFLAGS="$tmp_CFLAGS -Walloc-zero"
+            tmp_CFLAGS="$tmp_CFLAGS -Wformat-overflow=2"
+            tmp_CFLAGS="$tmp_CFLAGS -Wformat-truncation=2"
+          fi
+          #
         fi
         #
         dnl Do not issue warnings for code in system include paths.