From a19fefb0706f939d2df7a76704ee549fecb1c4fd Mon Sep 17 00:00:00 2001
From: Eric Gallager <egall@gwmail.gwu.edu>
Date: Mon, 12 Feb 2018 01:42:47 -0500
Subject: build: add picky compiler warning flags for gcc 6 and 7

---
 m4/curl-compilers.m4 | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

(limited to 'm4')

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.
-- 
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