[PATCH] D58682: Add secondary libstdc++ 4.8 and 5.1 detection mechanisms

[Hubert Tong via Phabricator via llvm-commits]

hubert.reinterpretcast created this revision.
hubert.reinterpretcast added reviewers: jfb, tstellar, rnk, sfertile, nemanjai.
Herald added a subscriber: mgorny.
Herald added a project: LLVM.

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++.


Repository:
  rL LLVM

https://reviews.llvm.org/D58682

Files:
  cmake/modules/CheckCompilerVersion.cmake


Index: cmake/modules/CheckCompilerVersion.cmake
===================================================================
--- cmake/modules/CheckCompilerVersion.cmake
+++ cmake/modules/CheckCompilerVersion.cmake
@@ -58,6 +58,7 @@
     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.
     check_cxx_source_compiles("
 #include <iosfwd>
 #if defined(__GLIBCXX__)
@@ -65,12 +66,19 @@
 #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().
     check_cxx_source_compiles("
 #include <iosfwd>
 #if defined(__GLIBCXX__)
@@ -78,6 +86,10 @@
 #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)


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