From 3307e10fc4ef5ffb551df35bc0978a2543305e9d Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Fri, 8 May 2015 11:04:21 -0400
Subject: Avoid using C++14 to build CMake if cstdio breaks
The GNU 4.8 standard library's cstdio header is not aware that C++14
honors C11's removal of "gets" from stdio.h and results in an error:
/.../include/c++/4.8/cstdio:120:11: error: no member named 'gets' in the global namespace
Detect this problematic case and default to using C++11 instead of
C++14 for building CMake itself.
---
CMakeLists.txt | 7 ++++++-
Source/Checks/cm_cxx14_cstdio.cmake | 33 +++++++++++++++++++++++++++++++++
Source/Checks/cm_cxx14_cstdio.cpp | 2 ++
3 files changed, 41 insertions(+), 1 deletion(-)
create mode 100644 Source/Checks/cm_cxx14_cstdio.cmake
create mode 100644 Source/Checks/cm_cxx14_cstdio.cpp
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e979d4f..19d83f1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -41,7 +41,12 @@ if(NOT DEFINED CMAKE_C_STANDARD AND NOT CMake_NO_C_STANDARD)
set(CMAKE_C_STANDARD 11)
endif()
if(NOT DEFINED CMAKE_CXX_STANDARD AND NOT CMake_NO_CXX_STANDARD)
- set(CMAKE_CXX_STANDARD 14)
+ include(${CMake_SOURCE_DIR}/Source/Checks/cm_cxx14_cstdio.cmake)
+ if(NOT CMake_CXX14_CSTDIO_BROKEN)
+ set(CMAKE_CXX_STANDARD 14)
+ else()
+ set(CMAKE_CXX_STANDARD 11)
+ endif()
endif()
# option to set the internal encoding of CMake to UTF-8
diff --git a/Source/Checks/cm_cxx14_cstdio.cmake b/Source/Checks/cm_cxx14_cstdio.cmake
new file mode 100644
index 0000000..73f7e2e
--- /dev/null
+++ b/Source/Checks/cm_cxx14_cstdio.cmake
@@ -0,0 +1,33 @@
+set(CMake_CXX14_CSTDIO_BROKEN 0)
+if(CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang" AND CMAKE_CXX14_STANDARD_COMPILE_OPTION)
+ if(NOT DEFINED CMake_CXX14_CSTDIO_WORKS)
+ message(STATUS "Checking if compiler supports C++14 cstdio")
+ try_compile(CMake_CXX14_CSTDIO_WORKS
+ ${CMAKE_CURRENT_BINARY_DIR}
+ ${CMAKE_CURRENT_LIST_DIR}/cm_cxx14_cstdio.cpp
+ CMAKE_FLAGS -DCMAKE_CXX_STANDARD=14
+ OUTPUT_VARIABLE OUTPUT
+ )
+ if(CMake_CXX14_CSTDIO_WORKS AND "${OUTPUT}" MATCHES "error: no member named.*gets.*in the global namespace")
+ set_property(CACHE CMake_CXX14_CSTDIO_WORKS PROPERTY VALUE 0)
+ endif()
+ if(CMake_CXX14_CSTDIO_WORKS)
+ message(STATUS "Checking if compiler supports C++14 cstdio - yes")
+ file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
+ "Determining if compiler supports C++14 cstdio passed with the following output:\n"
+ "${OUTPUT}\n"
+ "\n"
+ )
+ else()
+ message(STATUS "Checking if compiler supports C++14 cstdio - no")
+ file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+ "Determining if compiler supports C++14 cstdio failed with the following output:\n"
+ "${OUTPUT}\n"
+ "\n"
+ )
+ endif()
+ endif()
+ if(NOT CMake_CXX14_CSTDIO_WORKS)
+ set(CMake_CXX14_CSTDIO_BROKEN 1)
+ endif()
+endif()
diff --git a/Source/Checks/cm_cxx14_cstdio.cpp b/Source/Checks/cm_cxx14_cstdio.cpp
new file mode 100644
index 0000000..3a6a699
--- /dev/null
+++ b/Source/Checks/cm_cxx14_cstdio.cpp
@@ -0,0 +1,2 @@
+#include <cstdio>
+int main() { return 0; }
--
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