patch 8.2.0541: Travis CI does not give compiler warnings
Problem: Travis CI does not give compiler warnings.
Solution: Add flags for warnings. Fix uncovered problems. (Ozaki Kiichi,
closes #5898)
diff --git a/ci/config.mk.clang.sed b/ci/config.mk.clang.sed
new file mode 100644
index 0000000..40c6705
--- /dev/null
+++ b/ci/config.mk.clang.sed
@@ -0,0 +1 @@
+/^RUBY_CFLAGS\b/s/$/ -Wno-error=unknown-attributes -Wno-error=ignored-attributes/
diff --git a/ci/config.mk.gcc.sed b/ci/config.mk.gcc.sed
new file mode 100644
index 0000000..3b11569
--- /dev/null
+++ b/ci/config.mk.gcc.sed
@@ -0,0 +1 @@
+/^CFLAGS\b/s/$/ -Wno-error=maybe-uninitialized/
diff --git a/ci/config.mk.sed b/ci/config.mk.sed
new file mode 100644
index 0000000..3168278
--- /dev/null
+++ b/ci/config.mk.sed
@@ -0,0 +1,2 @@
+/^CFLAGS\b/s/$/ -Wall -Wextra -Wshadow -Werror/
+/^PERL_CFLAGS\b/s/$/ -Wno-error=unused-function/