Bugfix: add some c++ standard support check.

matrixji · matrixji · commit 083a0656ba7c · 2020-05-07T15:49:13.000Z
- check c++11/c++14 support in common.mk

Signed-off-by: Ji Bin &lt;matrixji@live.com&gt;
diff --git a/common.mk b/common.mk
@@ -1,15 +1,40 @@
 CXX_FLAGS=-Wall
+CXX=g++
+
+HAS_CPP14=$(shell \
+	echo > /tmp/dummy.cpp ; \
+	if $(CXX) -std=c++14 -c -o /dev/null /tmp/dummy.cpp 2>/dev/null ; then \
+		echo yes ; \
+	else \
+		echo no ; \
+	fi)
+
+HAS_CPP11=$(shell \
+	echo > /tmp/dummy.cpp ; \
+	if $(CXX) -std=c++11 -c -o /dev/null /tmp/dummy.cpp 2>/dev/null ; then \
+		echo yes ; \
+	else \
+		echo no ; \
+	fi)
+
+ifeq ($(HAS_CPP14), yes)
+	PREFER_STANDARD:=cpp14
+else
+ifeq ($(HAS_CPP11), yes)
+	PREFER_STANDARD:=cpp11
+endif
+endif
 
 all: examples
 
 example_%_cpp14: %.cpp
-	g++ -std=c++14 -o $@ $^ $(CXX_FLAGS) $($@_cxx_flags) $($@_ld_flags) 
+	$(CXX) -std=c++14 -o $@ $^ $(CXX_FLAGS) $($@_cxx_flags) $($@_ld_flags)
 
 example_%_cpp11: %.cpp
-	g++ -std=c++11 -o $@ $^ $(CXX_FLAGS) $($@_cxx_flags) $($@_ld_flags)
+	$(CXX) -std=c++11 -o $@ $^ $(CXX_FLAGS) $($@_cxx_flags) $($@_ld_flags)
 
 example_%_cpp98: %.cpp
-	g++ -std=c++98 -o $@ $^ $(CXX_FLAGS) $($@_cxx_flags) $($@_ld_flags)
+	$(CXX) -std=c++98 -o $@ $^ $(CXX_FLAGS) $($@_cxx_flags) $($@_ld_flags)
 
 clean:
 	rm -fr example_*
diff --git a/section0/Makefile b/section0/Makefile
@@ -1,3 +1,9 @@
 include ../common.mk
 
-examples: example_test_cpp14 example_test_cpp11
+ifeq ($(HAS_CPP14), yes)
+examples: example_test_cpp14
+endif
+
+ifeq ($(HAS_CPP11), yes)
+examples: example_test_cpp11
+endif
diff --git a/section1/Makefile b/section1/Makefile
@@ -1,10 +1,21 @@
 include ../common.mk
 
+
+ifeq ($(HAS_CPP14), yes)
+examples: \
+	example_codestyle_cpp14 \
+	example_compile_cpp14 \
+	example_oop_cpp14 \
+	example_preprocess_cpp14
+endif
+
+ifeq ($(HAS_CPP11), yes)
 examples: \
-	example_codestyle_cpp14 example_codestyle_cpp11 \
-	example_compile_cpp14 example_compile_cpp11 \
-	example_oop_cpp14 example_oop_cpp11 \
-	example_preprocess_cpp14 example_preprocess_cpp11
+	example_codestyle_cpp11 \
+	example_compile_cpp11 \
+	example_oop_cpp11 \
+	example_preprocess_cpp11
+endif
 
 # example_preprocess_cpp98 is showing version check with compile failed.
 # please explicit using `make example_preprocess_cpp98` under section1 folder
diff --git a/section2/Makefile b/section2/Makefile
@@ -1,8 +1,15 @@
 include ../common.mk
 
+ifeq ($(HAS_CPP14), yes)
 examples: \
-	example_auto_cpp14 example_auto_cpp11 \
-	example_const_cpp14 example_const_cpp11 \
-	example_exception_cpp14 example_exception_cpp11 \
-	example_lambda_cpp14 example_lambda_cpp11 \
-	example_smart_ptr_cpp14 example_smart_ptr_cpp11
+	example_auto_cpp14 \
+	example_const_cpp14 \
+	example_exception_cpp14 \
+	example_lambda_cpp14 \
+	example_smart_ptr_cpp14
+endif
+
+ifeq ($(HAS_CPP11), yes)
+examples: \
+	example_exception_cpp11
+endif
diff --git a/section3/Makefile b/section3/Makefile
@@ -3,8 +3,11 @@ include ../common.mk
 example_thread_cpp14_ld_flags=-lpthread
 example_thread_cpp11_ld_flags=-lpthread
 
+
+ifeq ($(HAS_CPP14), yes)
 examples: \
-	example_algo_cpp14 example_algo_cpp11 \
-	example_container_cpp14 example_container_cpp11 \
-	example_string_cpp14 example_string_cpp11 \
-	example_thread_cpp14 example_thread_cpp11
+	example_algo_cpp14 \
+	example_container_cpp14 \
+	example_string_cpp14 \
+	example_thread_cpp14
+endif
