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Code Issues Releases Activity

SERVER-13527 Enable C++11 automatically when reasonable to do so

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This commit is contained in:
Andrew Morrow 2014-04-12 14:51:24 -04:00
parent a475a70e90
commit 6cef43b784
1 changed files with 89 additions and 21 deletions
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@ -216,7 +216,8 @@ add_option( "cc", "compiler to use for c" , 1 , True )
add_option( "cc-use-shell-environment", "use $CC from shell for C compiler" , 0 , False )
add_option( "cxx-use-shell-environment", "use $CXX from shell for C++ compiler" , 0 , False )
add_option( "ld", "linker to use" , 1 , True )
add_option( "c++11", "enable c++11 support (experimental)", 0, True )
add_option( "c++11", "enable c++11 support (experimental)", "?", True,
type="choice", choices=["on", "off", "auto"], const="on", default="auto" )
add_option( "cpppath", "Include path if you have headers in a nonstandard directory" , 1 , False )
add_option( "libpath", "Library path if you have libraries in a nonstandard directory" , 1 , False )
@ -1150,21 +1151,6 @@ def doConfigure(myenv):
# primary mongo sources as well.
AddToCCFLAGSIfSupported(myenv, "-Wno-unused-const-variable")
if has_option('c++11'):
# The Microsoft compiler does not need a switch to enable C++11. Again we should be
# checking for MSVC, not windows. In theory, we might be using clang or icc on windows.
if not using_msvc():
# For our other compilers (gcc and clang) we need to pass -std=c++0x or -std=c++11,
# but we prefer the latter. Try that first, and fall back to c++0x if we don't
# detect that --std=c++11 works.
if not AddToCXXFLAGSIfSupported(myenv, '-std=c++11'):
if not AddToCXXFLAGSIfSupported(myenv, '-std=c++0x'):
print( 'C++11 mode requested, but cannot find a flag to enable it' )
Exit(1)
if not AddToCFLAGSIfSupported(myenv, '-std=c99'):
print( 'C++11 mode selected for C++ files, but failed to enable C99 for C files' )
# This needs to happen before we check for libc++, since it affects whether libc++ is available.
if darwin and has_option('osx-version-min'):
min_version = get_option('osx-version-min')
@ -1236,11 +1222,93 @@ def doConfigure(myenv):
haveGoodLibStdCxx = conf.CheckModernLibStdCxx()
conf.Finish()
if has_option('c++11') and usingLibStdCxx and not haveGoodLibStdCxx:
print( 'Detected libstdc++ is too old to support C++11 mode' )
if darwin:
print( 'Try building with --libc++ and --osx-version-min=10.7 or higher' )
Exit(1)
# Sort out whether we can and should use C++11:
cxx11_mode = get_option("c++11")
if using_msvc():
if cxx11_mode == "off":
print( 'WARNING: Cannot disable C++11 features when using MSVC' )
else:
# In C++11 'auto' mode, don't use C++11 if we are linking against any system C++ libs.
if cxx11_mode == "auto" and using_system_version_of_cxx_libraries():
cxx11_mode = "off"
# If we are using libstdc++, only allow C++11 mode with our line-in-the-sand good
# libstdc++. As always, if in auto mode fall back to disabling if we don't have a good
# libstdc++, otherwise fail the build because we can't honor the explicit request.
if cxx11_mode != "off" and usingLibStdCxx:
if not haveGoodLibStdCxx:
if cxx11_mode == "auto":
cxx11_mode = "off"
else:
print( 'Detected libstdc++ is too old to support C++11 mode' )
if darwin:
print( 'Try building with --libc++ and --osx-version-min=10.7 or higher' )
Exit(1)
# We are going to be adding flags to the environment, but we don't want to persist
# those changes unless we pass all the below checks. Make a copy of the environment
# that we will modify, we will only "commit" the changes to the env if we pass all the
# checks.
cxx11Env = myenv.Clone()
# For our other compilers (gcc and clang) we need to pass -std=c++0x or -std=c++11,
# but we prefer the latter. Try that first, and fall back to c++0x if we don't
# detect that --std=c++11 works. If we can't find a flag and C++11 was explicitly
# requested, error out, otherwise turn off C++11 support in auto mode.
if cxx11_mode != "off":
if not AddToCXXFLAGSIfSupported(cxx11Env, '-std=c++11'):
if not AddToCXXFLAGSIfSupported(cxx11Env, '-std=c++0x'):
if cxx11_mode == "auto":
cxx11_mode = "off"
else:
print( 'C++11 mode requested, but cannot find a flag to enable it' )
Exit(1)
# We appear to have C++11, or at least a flag to enable it, which is now set in the
# environment. If we are in auto mode, check if the compiler claims that it strictly
# supports C++11, and disable C++11 if not. If the user has explicitly requested C++11,
# we don't care about what the compiler claims to support, trust the user.
if cxx11_mode == "auto":
def CheckCxx11Official(context):
test_body = """
#if __cplusplus < 201103L
#error
#endif
const int not_an_empty_file = 0;
"""
context.Message('Checking if __cplusplus >= 201103L to auto-enable C++11... ')
ret = context.TryCompile(textwrap.dedent(test_body), ".cpp")
context.Result(ret)
return ret
conf = Configure(cxx11Env, help=False, custom_tests = {
'CheckCxx11Official' : CheckCxx11Official,
})
if cxx11_mode == "auto" and not conf.CheckCxx11Official():
cxx11_mode = "off"
conf.Finish()
# We require c99 mode for C files when C++11 is enabled, so perform the same dance
# as above: if C++11 mode is not off, try the flag, if we are in auto mode and we fail
# then turn off C++11, otherwise C++11 was explicitly requested and we should error out.
if cxx11_mode != "off":
if not AddToCFLAGSIfSupported(cxx11Env, '-std=c99'):
if cxx11_mode == "auto":
cxx11_mode = "off"
else:
print( "C++11 mode selected for C++ files, but can't enable C99 for C files" )
Exit(1)
# If we got here and cxx11_mode hasn't become false, then its true, so swap in the
# modified environment.
if cxx11_mode != "off":
cxx11_mode = "on"
myenv = cxx11Env
# If we are using a modern libstdc++ and this is a debug build and we control all C++
# dependencies, then turn on the debugging features in libstdc++.