Implement a cpp.exceptionHandling property to control availability of exception handling

As discussed on the mailing list.

Module: cpp
Property name: enableExceptions
Property type: bool
Default value: undefined

• undefined - do nothing (exceptionHandlingModel also has no effect)
• true - see exceptionHandlingModel for what happens
• false - -fno-exceptions and -fno-objc-exceptions for GCC-family compilers, /EH- for MSVC-family compilers

Module: cpp
Property name: exceptionHandlingModel
Property type: string
Default value: "default"
Allowed values:

• MSVC:
  • "default" = /EHsc
  • "seh" = /EHa
  • "externc" = /EHs
• GCC/MinGW:
  • "default" = -fexceptions, -fobjc-exceptions, -fobjc-arc-exceptions
• MinGW:
  • "sjlj"
  • "seh"
  • "dwarf2" (or just "dwarf"?)

Toolchain setup should set the value of exceptionHandlingModel.

—

Visual Studio 2012's property pages option "Enable C++ Exceptions" gives the following choices:

• Yes with SEH exceptions (/EHa)
• Yes (/EHsc)
• Yes with Extern C functions (/EHs)
• No
• <inherit from parent or project defaults>

The documentation states "If /EH is not specified (i.e. "No" in VS), the compiler catches structured exceptions and C++ exceptions, but does not destroy C++ objects that go out of scope as a result of an exception."