1 files changed, 92 insertions, 0 deletions
diff --git a/m4/wget_manywarnings.m4 b/m4/wget_manywarnings.m4
new file mode 100644
index 0000000..9bc5ee5
--- /dev/null
+++ b/m4/wget_manywarnings.m4
@@ -0,0 +1,92 @@
+# wget_manywarnings.m4 serial 1
+dnl Copyright (C) 2016-2020 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl From Tim Ruehsen
+
+# wget_WORD_SET(RESULT, SET, WORDS)
+# --------------------------------------------------
+# Add each word in WORDS to SET if not already there and store in RESULT.
+# Words separated by whitespace.
+AC_DEFUN([wget_WORD_SET], [
+  ret=$2
+  words=" $2 "
+  for word in $3; do
+    if test "${words#*" $word "}" = "$words"; then ret="$ret $word"; fi
+  done
+  $1=$ret
+])
+
+# wget_WORD_REMOVE(RESULT, SET, WORDS)
+# --------------------------------------------------
+# Remove each word in WORDS from SET and store in RESULT.
+# Words separated by whitespace.
+AC_DEFUN([wget_WORD_REMOVE], [
+  ret=
+  words=" $3 "
+  for word in $2; do
+     if test "${words#*" $word "}" = "$words"; then ret="$ret $word"; fi
+  done
+  $1=$ret
+])
+
+# wget_MANYWARNINGS(VARIABLE, LANGUAGE)
+# -----------------------------
+# Add LANGUAGE related GCC warnings to VARIABLE.
+# This only works for gcc >= 4.3.
+AC_DEFUN([wget_MANYWARNINGS], [
+  #
+  # check if manywarnings is requested
+  #
+  AC_ARG_ENABLE([manywarnings],
+    [AS_HELP_STRING([--enable-manywarnings], [Turn on extra compiler warnings (for developers)])],
+    [case $enableval in
+       yes|no) ;;
+       *) AC_MSG_ERROR([Bad value $enableval for --enable-manywarnings option]) ;;
+     esac
+       wget_manywarnings=$enableval
+    ], [
+      test -f .manywarnings && wget_manywarnings=yes || wget_manywarnings=no
+    ]
+  )
+
+  $1=""
+
+  if test "$wget_manywarnings" = yes; then
+    # AC_PROG_CC sets $GCC to 'yes' if compiler is gcc
+    # AC_REQUIRE([AC_PROG_CC])
+
+    case $CC in
+      *gcc*) CCNAME="gcc";;
+      *clang*) CCNAME="clang";;
+    esac
+
+    if test "$CCNAME" = "gcc"; then
+      test -n "$2" && wget_LANGUAGE=$2 || wget_LANGUAGE=C
+
+      # add -Wall -Wextra to reduce number of warn flags
+      wget_WORD_SET([wget_WARN_CFLAGS], [$CFLAGS], ["-Wall -Wextra -Wformat=2"])
+
+      # collect all disabled warn flags in $WARN_CFLAGS
+      wget_WARN_CFLAGS=$wget_WARN_CFLAGS" "$($CC $wget_WARN_CFLAGS -Q --help=warning,$wget_LANGUAGE|\
+        awk '{ if (([$]2 == "[[disabled]]" || [$]2 == "")\
+          && [$]1!~/=/ && [$]1~/^-W/ && [$]1!~/</ && [$]1!="-Wall") print [$]1 }')
+
+      GCC_VERSION=$($CC -dumpversion | cut -f1 -d.)
+      if test $GCC_VERSION -ge 6; then
+        wget_WARN_CFLAGS=$wget_WARN_CFLAGS" -Warray-bounds=2 -Wnormalized=nfc -Wshift-overflow=2 -Wunused-const-variable=2"
+      fi
+      if test $GCC_VERSION -ge 7; then
+        wget_WARN_CFLAGS=$wget_WARN_CFLAGS" -Wformat-overflow=2 -Wformat-truncation=1 -Wstringop-overflow=2"
+      fi
+
+    elif test "$CCNAME" = "clang"; then
+      # set all warn flags on
+      wget_WORD_SET([wget_WARN_CFLAGS], [$CFLAGS], ["-Weverything"])
+    fi
+
+    $1=$wget_WARN_CFLAGS
+  fi
+])