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.

Note: Several compatibility options have switches beginning with -Vb. These options are summarized in the following table:

Command-Line Switch	Meaning
-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.
-Vbe	Allow old-style explicit template specialization.
-Vbn	Allow calling a non-const member function for a const object.
-Vbo	Use old overload resolution rules.
-Vbr	Allow non-const reference binding.
-Vbs	Do not treat string literals as const.
-Vbt	Use old Borland type rules for ternary operators.
-Vbx	Allow explicit template specializations as member functions.

Options	Description
Build Configuration Options	Described in Build Configuration Options.
Common Options	Described in Common Items on Project Options Pages.

C++ Compatibility options	Description
'Slow' virtual base pointers (-Vv)	Uses 'slow' virtual base pointers. Default = False
Constructor displacements (-Vc)	Supports constructor displacements. Default = False
Explicit template specialization as member function (-Vbx)	Allow explicit template specializations as member functions. Default = False
Old Borland class layout (-VI)	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 C++Builder. Enable this option if you need to compile source files that you intend to use with older versions of C++Builder (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 (-Va)	Supports old style class arguments. Default = False
Old-style explicit template specialization (-Vbe)	Allow old-style explicit template specialization. Default = False
Old style virdef generation (-Vs)	Uses old-style virdef generation. Default = False
Push 'this' first (-Vp)	Like Pascal, pushes 'this' first. The compiler typically pushes parameters on the stack from right to left. Default = False
VC++ compatibility (-VM)	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 (-Vt)	Puts virtual table pointer at front of object layout. Default = False
Zero-length empty base class (-Ve)	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 (-Vx)	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 option	Description
Backward compatibility (-Vb)	Enables all the -Vxxx options for backward compatibility. Default = False
Disable lexical digraph scanner (-Vg)	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 and allow qualified references (-Vbc)	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 specify the -Vbc switch, intrr is reported as an error just as it previously would have been an error. A qualified reference was also illegal previously. The new rules call for the qualifiers to be collapsed when they are the result of a typedef. For example: typedef int & intr; typedef intcr const; Under the new C++ rules, intcr is legal and is the same type as intr. Bcc32 follows these rules by default. Under the previous rules, intcr would be illegal, but bcc32 Rev 5.9 (and before) allowed this, treating the type as if qualified references were legal. If you specify -Vbc, intcr is treated as the type int & const.
Don't mangle calling convention (-VC)	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 (-Vo)	Sets most of the compatibility flags used with old code, enabling -Vv , -Va, -Vp, -Vt, -Vc, -Vd, and -Vx. Default = False
Enable new operator names (-Vn)	Enables new operator names such as 'and', 'or', 'and_eq', 'bitand', and so forth. Default = False
for-statement scoping (-Vd)	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 -Vd } //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'll get an Undefined Symbol compilation error if you compile this code with this option disabled.If this option is set (-Vd), 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 ( -VA)	Generates all global functions in their own virtual or weak segment. Default = True
Microsoft header search algorithm (-VI)	Uses Microsoft search algorithms to locate the header files. Default = True
Native code for MBCS (-Vw)	Emits native code instead of Unicode for multi-byte character. Default = False
Non-const calls for const object (-Vbn)	Allow calling a non-const member function for a const object. Default = False
Non-const reference binding (-Vbr)	Allow non-const reference binding. Default = False
Non-const string literals (-Vbs)	Do not treat string literals as const. Default = False
Old 8.3 include search (-Vi)	Use old 8.3 search algorithm to locate header files. Default = False
Old overload resolution (-Vbo)	Use old overload resolution rules. Default = False
Reverse Multi-character constants (-Vr)	The compiler reverses the order of Multi-character constants. Default = False

General option	Description
Default	Saves the current settings as the default for each new project.