drgn/libdrgn/m4/ax_append_compile_flags.m4
Omar Sandoval 24609a3a2e libdrgn: add autoconf option to enable compiler warnings
This adds an --enable-compiler-warnings flag that:

* Defines a canonical list of warnings that we enforce. For now, this is
  -Wall -Wformat-overflow=2 -Wformat-truncation=2, but we can add to it
  going forward.
* Enables warnings by default.
* Allows erroring on warnings. We recommend that developers use this and
  use it for the CI.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
2022-03-01 15:38:05 -08:00

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# ============================================================================
# https://www.gnu.org/software/autoconf-archive/ax_append_compile_flags.html
# ============================================================================
#
# SYNOPSIS
#
# AX_APPEND_COMPILE_FLAGS([FLAG1 FLAG2 ...], [FLAGS-VARIABLE], [EXTRA-FLAGS], [INPUT])
#
# DESCRIPTION
#
# For every FLAG1, FLAG2 it is checked whether the compiler works with the
# flag. If it does, the flag is added FLAGS-VARIABLE
#
# If FLAGS-VARIABLE is not specified, the current language's flags (e.g.
# CFLAGS) is used. During the check the flag is always added to the
# current language's flags.
#
# If EXTRA-FLAGS is defined, it is added to the current language's default
# flags (e.g. CFLAGS) when the check is done. The check is thus made with
# the flags: "CFLAGS EXTRA-FLAGS FLAG". This can for example be used to
# force the compiler to issue an error when a bad flag is given.
#
# INPUT gives an alternative input source to AC_COMPILE_IFELSE.
#
# NOTE: This macro depends on the AX_APPEND_FLAG and
# AX_CHECK_COMPILE_FLAG. Please keep this macro in sync with
# AX_APPEND_LINK_FLAGS.
#
# LICENSE
#
# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
#serial 7
AC_DEFUN([AX_APPEND_COMPILE_FLAGS],
[AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG])
AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
for flag in $1; do
AX_CHECK_COMPILE_FLAG([$flag], [AX_APPEND_FLAG([$flag], [$2])], [], [$3], [$4])
done
])dnl AX_APPEND_COMPILE_FLAGS