From 81400d3edcdab9e468ed0cb3557fdcdacf6475a6 Mon Sep 17 00:00:00 2001
From: Sebastian Reimers <hallo@studio-link.de>
Date: Tue, 22 Dec 2020 11:44:12 +0100
Subject: [PATCH] mk/re: add C11 and Atomic detection (#61)

Adding C11 detection (gcc/clang 5.x and newer). It can be disabled with make CC_C11=. When C11 is detected, it defines HAVE_ATOMIC. This can also be disabled with make HAVE_ATOMIC=.
---
 README.md |  2 +-
 mk/re.mk  | 27 +++++++++++++++++++++++----
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 9438e65ba..317ef3e2a 100644
--- a/README.md
+++ b/README.md
@@ -88,7 +88,7 @@ Please send private feedback to libre [at] creytiv.com
 
 ## Design goals
 
-* Portable POSIX source code (ANSI C89 and ISO C99 standard)
+* Portable POSIX source code (ISO C99 and C11 standard)
 * Robust, fast, low memory footprint
 * RFC compliance
 * IPv4 and IPv6 support
diff --git a/mk/re.mk b/mk/re.mk
index 61382a1b2..9f8a4e9f8 100644
--- a/mk/re.mk
+++ b/mk/re.mk
@@ -79,22 +79,31 @@ ifeq ($(CC),cc)
 	CC := gcc
 endif
 LD := $(CC)
-CC_LONGVER := $(shell $(CC) - --version|head -n 1)
+
+CC_LONGVER  := $(shell $(CC) - --version|head -n 1)
 CC_SHORTVER := $(shell $(CC) -dumpversion)
+CC_MAJORVER := $(shell echo $(CC_SHORTVER) |\
+			sed -e 's/\([0-9]*\)\.[0-9]\+\.[0-9]\+/\1/g')
 
 # find-out the compiler's name
 
 ifneq (,$(findstring gcc, $(CC_LONGVER)))
 	CC_NAME := gcc
-	CC_VER := $(CC) $(CC_SHORTVER)
+	CC_VER := $(CC) $(CC_SHORTVER) ($(CC_MAJORVER).x)
 	MKDEP := $(CC) -MM
+ifneq ($(CC_MAJORVER), 4)
+	CC_C11 := 1
+endif
 endif
 
 ifeq ($(CC_NAME),)
 ifneq (,$(findstring clang, $(CC_LONGVER)))
 	CC_NAME := clang
-	CC_VER := $(CC) $(CC_SHORTVER)
+	CC_VER := $(CC) $(CC_SHORTVER) ($(CC_MAJORVER).x)
 	MKDEP := $(CC) -MM
+ifneq ($(CC_MAJORVER), 4)
+	CC_C11 := 1
+endif
 endif
 endif
 
@@ -295,9 +304,19 @@ endif
 
 CFLAGS	+= -DOS=\"$(OS)\"
 
+ifeq ($(CC_C11),)
 CFLAGS  += -std=c99
+else
+CFLAGS  += -std=c11
+HAVE_ATOMIC := 1
+endif
+
 CFLAGS  += -pedantic
 
+ifneq ($(HAVE_ATOMIC),)
+CFLAGS  += -DHAVE_ATOMIC
+endif
+
 
 ifeq ($(OS),)
 $(warning Could not detect OS)
@@ -613,7 +632,7 @@ info:
 	@echo "  OS:            $(OS)"
 	@echo "  BUILD:         $(BUILD)"
 	@echo "  CCACHE:        $(CCACHE)"
-	@echo "  CC:            $(CC_NAME) $(CC_SHORTVER)"
+	@echo "  CC:            $(CC_VER)"
 	@echo "  CFLAGS:        $(CFLAGS)"
 	@echo "  DFLAGS:        $(DFLAGS)"
 	@echo "  LFLAGS:        $(LFLAGS)"