C++ Compiler Compatibility

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Project > Options > C++ Compiler > Compatibility

Use this dialog box to set specific C++ compiler compatibility options.

The options on this dialog box provide backward compatibility with previous versions of the compiler. In general, these options should only be set to True when such compatibility is required. Their default values are typically False.

Options	Description
Target, Apply, Save	See Target Options.
Common items	See Common Items on Project Options Pages.

C++ Compatibility Options

C++ Compatibility Options	Description	Compiler support
		bcc32	bcc32c	bcc64	bccosx	bcciosarm	bcciosarm64	bccaarm
'Slow' virtual base pointers	Uses 'slow' virtual base pointers. Default = False
Constructor displacements	Supports constructor displacements. Default = False
Explicit template specialization as member function	Allow explicit template specializations as member functions. Default = False
Old Borland class layout	This is a backward compatibility switch that causes the C++ compiler to lay out derived classes the same way it did in older versions of Appmethod C++. Enable this option if you need to compile source files that you intend to use with older versions of Appmethod C++ (for example, if you need to work with a DLL that you cannot recompile, or if you have older data files that contain hardwired class layouts). Default = False
Old-style class arguments	Supports old style class arguments. Default = False
Old-style explicit template specialization	Allow old-style explicit template specialization. Default = False
Old style virdef generation	Uses old-style virdef generation. Default = False
Push 'this' first	Like Pascal, pushes 'this' first. The compiler typically pushes parameters on the stack from right to left. Default = False
VC++ compatibility	To provide compatibility with Microsoft Visual C++, substitutes __msfastcall for __fastcall calling convention. This switch should not be used when working with a VCL application. It causes numerous linker errors. Default = False
VTable in front	Puts virtual table pointer at front of object layout. Default = False
Zero-length empty base class	Usually the size of a class is at least one byte, even if the class does not define any data members. When you set this option, the compiler ignores this unused byte for the memory layout and the total size of any derived classes; empty base classes do not consume space in derived classes. Default = False
Zero-length empty class member functions	Usually the size of a data member in a class definition is at least one byte. When this option is enabled, the compiler allows an empty structure of zero length. Default = False

General Options

General Options	Description	Compiler switches
		bcc32	bcc32c	bcc64	bccosx	bcciosarm	bcciosarm64	bccaarm
Backward compatibility	Enables all the compatibility options for backward compatibility. Default = False
Disable lexical digraph scanner	Disables the lexical digraph scanner. Digraphs are two character sequences that stand in for a single character that may be hard to produce on certain keyboards. If this option is true, then such diagraphs are not recognized.Default = False
Don't collapse ref-to-ref	Previously, a reference to a reference was illegal. The new default behavior is to follow the C++0x rules. The compiler now collapses the two references. For example: typedef int & intr; typedef intrr &; The type intrr is legal, the same type as intr under the new C++ rules. Bcc32 (Rev. 6.0 and above) follows these rules by default. Under the previous C++ rules, intrr would be illegal. If you enable the Don't collapse ref-to-ref option, intrr is reported as an error just as it previously would have been an error.
Don't mangle calling convention	When this option is set, the compiler disables the distinction of function names where the only possible difference is incompatible code generation options. For example, with this option set, the linker does not detect if a call is made to a __fastcall member function with the cdecl calling convention.This option is provided for backward compatibility only; it lets you link old library files that you cannot recompile. Default = False
Enable all compatibility options	Enables most of the compatibility options used with old code: 'Slow' virtual base pointers Old-style class arguments Push 'this' first VTable in front Constructor displacements for -statement scoping Zero-length empty class member functions Default = False
Enable new operator names	Enables new operator names such as 'and', 'or', 'and_eq', 'bitand', and so forth. Default = False
for -statement scoping	Specifies the scope of variables declared in for loop expressions. The output of the following code segment changes, depending on the setting of this option: int main(void) { for(int i=0; i<10; i++) { cout << "Inside for loop, i = " << i << endl; } //end of for-loop block cout << "Outside for loop, i = " << i << endl; //error without this option } //end of block containing for loop If this option is disabled (the default), the variable i goes out of scope when processing reaches the end of the for loop. Because of this, you will get an Undefined Symbol compilation error if you compile this code with this option disabled. If the for -statement scoping option is enabled, the variable i goes out of scope when processing reaches the end of the block containing the for loop. In this case, the code output would be: Inside for loop, i = 0 ... Outside for loop, i = 10 Default = False
Global functions in segments	Generates all global functions in their own virtual or weak segment. Default = True
Microsoft header search algorithm	Uses Microsoft search algorithms to locate the header files. Default = True
Native code for MBCS	Emits native code instead of Unicode for multi-byte character. Default = False
Non-const calls for const object	Allow calling a non-const member function for a const object. Default = False
Non-const reference binding	Allow non-const reference binding. Default = False
Non-const string literals	Do not treat string literals as const. Default = False
Old 'using' rules in templates	Use the old Borland rules for 'using' in templates. Default = False
Old 8.3 include search	Use old 8.3 search algorithm to locate header files. Default = False
Old overload resolution	Use old overload resolution rules. Default = False
Old type rules for ternary operators	Use the old Borland type rules for ternary operators. Default = False
Reverse Multi-character constants	The compiler reverses the order of Multi-character constants. Default = False

-Vb Compiler Options for BCC32/BCCOSX

Note: Several compatibility options have compiler switches for BCC32 and BCCOSX that begin with -Vb. BCC64 does not support these compatibility options. The -Vb compatibility options are summarized in the following table:

Command-Line Switch	Meaning
-Va	Support old-style class arguments.
-Vb	Turn on all -Vb switches. Enables backward compatibility with Bcc versions 5.8.2 and earlier.
-Vb+	Turn on all -Vb switches.
-Vb-	Turn off all -Vb switches.
-Vb.	Reset all -Vb switches to their default values. Available only on the command line, not in the IDE.
-Vbc	Do not collapse reference to reference and allow qualified references.
-Vbe	Allow old-style explicit template specialization.
-Vi	Use old 8.3 algorithm to locate header files.
-Vbn	Allow calling of non-const or non-volatile member function for a const or volatile object.
-Vbo	Use old Borland overload resolution rules.
-Vbr	Allow old Borland rules for reference binding.
-Vbs	Treat string literals as non-const.
-Vbt	Use old Borland type rules for ternary operators.
-Vbu	Use old Borland rules for using in templates.
-Vbx	Allow explicit template specializations as member functions.

See Also

• Options Not Supported by Clang-enhanced C++ Compilers
• C++ (Shared Options)
• BCC32, the C++ Compiler for 32-bit Windows
• BCC32C.EXE
• BCC64, the C++ Compiler for 64-bit Windows
• BCCOSX, the C++ Compiler for OS X
• BCCIOSARM, the C++ Compiler for the 32-bit iOS Device
• BCCIOSARM64, the C++ Compiler for the 64-bit iOS Device
• BCCAARM, the C++ Compiler for Android