[llvm] r355638 - Add secondary libstdc++ 4.8 and 5.1 detection mechanisms

[Hubert Tong via llvm-commits]

Author: hubert.reinterpretcast
Date: Thu Mar  7 13:28:33 2019
New Revision: 355638

URL: http://llvm.org/viewvc/llvm-project?rev=355638&view=rev
Log:
Add secondary libstdc++ 4.8 and 5.1 detection mechanisms

Summary:
The date-based approach to detecting unsupported versions of libstdc++
does not handle bug fix releases of older versions. As an example, the
`__GLIBCXX__` value associated with version 5.1, `20150422`, is less
than the values associated with versions 4.8.5 and 4.9.3.

This patch adds secondary checks based on certain properties in
sufficiently new versions of libstdc++.

Reviewers: jfb, tstellar, rnk, sfertile, nemanjai

Reviewed By: jfb

Subscribers: mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58682

Modified:
    llvm/trunk/cmake/modules/CheckCompilerVersion.cmake

Modified: llvm/trunk/cmake/modules/CheckCompilerVersion.cmake
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/cmake/modules/CheckCompilerVersion.cmake?rev=355638&r1=355637&r2=355638&view=diff
==============================================================================
--- llvm/trunk/cmake/modules/CheckCompilerVersion.cmake (original)
+++ llvm/trunk/cmake/modules/CheckCompilerVersion.cmake Thu Mar  7 13:28:33 2019
@@ -58,6 +58,8 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang
     set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
     set(OLD_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
     set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++0x")
+    # Test for libstdc++ version of at least 4.8 by checking for _ZNKSt17bad_function_call4whatEv.
+    # Note: We should check _GLIBCXX_RELEASE when possible (i.e., for GCC 7.1 and up).
     check_cxx_source_compiles("
 #include <iosfwd>
 #if defined(__GLIBCXX__)
@@ -65,12 +67,20 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang
 #error Unsupported libstdc++ version
 #endif
 #endif
-int main() { return 0; }
+#if defined(__GLIBCXX__)
+extern const char _ZNKSt17bad_function_call4whatEv[];
+const char *chk = _ZNKSt17bad_function_call4whatEv;
+#else
+const char *chk = \"\";
+#endif
+int main() { ++chk; return 0; }
 "
       LLVM_LIBSTDCXX_MIN)
     if(NOT LLVM_LIBSTDCXX_MIN)
       message(FATAL_ERROR "libstdc++ version must be at least ${GCC_MIN}.")
     endif()
+    # Test for libstdc++ version of at least 5.1 by checking for std::iostream_category().
+    # Note: We should check _GLIBCXX_RELEASE when possible (i.e., for GCC 7.1 and up).
     check_cxx_source_compiles("
 #include <iosfwd>
 #if defined(__GLIBCXX__)
@@ -78,6 +88,10 @@ int main() { return 0; }
 #error Unsupported libstdc++ version
 #endif
 #endif
+#if defined(__GLIBCXX__)
+#include <ios>
+void foo(void) { (void) std::iostream_category(); }
+#endif
 int main() { return 0; }
 "
       LLVM_LIBSTDCXX_SOFT_ERROR)