ncurses: Add -std=gnu17 to CFLAGS to avoid a GCC15 error when building with glibc

Without the newly introduced flag, building with libc ends in errors such the below.
There is an upstream fix[1], but backporting it is not straight forward.

/scratch/union/staging_dir/toolchain-x86_64_gcc-15.1.0_glibc/x86_64-openwrt-linux-gnu/include/c++/15.1.0/cstddef:81:21: error: redefinition of 'struct std::__byte_operand<unsigned char>'
   81 |   template<> struct __byte_operand<unsigned char> { using __type = byte; };
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/scratch/union/staging_dir/toolchain-x86_64_gcc-15.1.0_glibc/x86_64-openwrt-linux-gnu/include/c++/15.1.0/cstddef:78:21: note: previous definition of 'struct std::__byte_operand<unsigned char>'
   78 |   template<> struct __byte_operand<bool> { using __type = byte; };
      |                     ^~~~~~~~~~~~~~~~~~~~
make[4]: *** [Makefile:438: ../obj_s/cursesp.o] Error 1

1. https://ncurses.scripts.mit.edu/?p=ncurses.git;a=commit;h=394a1a6cf317912584592e33184ef550e738a4b9

Signed-off-by: John Audia <therealgraysky@proton.me>
Link: https://github.com/openwrt/openwrt/pull/19335
Signed-off-by: Robert Marko <robimarko@gmail.com>

diff --git a/package/libs/ncurses/Makefile b/package/libs/ncurses/Makefile
index 0fcc3888401478d6c7000cfa1e5de865487084ab..b6b9a4eb8968a6d6dcd0f1e56bbea06df1b87d6e 100644 (file)
--- a/package/libs/ncurses/Makefile
+++ b/package/libs/ncurses/Makefile
@@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
 PKG_NAME:=ncurses
 PKG_CPE_ID:=cpe:/a:gnu:ncurses
 PKG_VERSION:=6.4
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=@GNU/$(PKG_NAME)
@@ -52,7 +52,7 @@ define Package/libncurses-dev
   TITLE:=Development files for the ncurses library
 endef
 
-TARGET_CFLAGS += $(FPIC)
+TARGET_CFLAGS += $(FPIC) -std=gnu17
 
 CONFIGURE_ARGS += \
        --enable-echo \