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2.7.1 Standard Predefined Versions ¶

The standard predefined versions are documented by the D language specification hosted at https://dlang.org/spec/version.html#predefined-versions.

all

none

Version none is never defined; used to just disable a section of code. Version all is always defined; used as the opposite of none.

BigEndian

LittleEndian

These versions reflect the byte order of multi-byte data in memory. LittleEndian is set when the least significant byte is first. BigEndian is set when the most significant byte is first.

CRuntime_Bionic

CRuntime_Glibc

CRuntime_Microsoft

CRuntime_Musl

CRuntime_Newlib

CRuntime_UClibc

These versions reflect which standard C library is being linked in. CRuntime_Bionic is set when Bionic is the default C library. CRuntime_Glibc is set when GLIBC is the default C library. CRuntime_Microsoft is set when MSVCRT is the default C library. CRuntime_Musl is set when musl is the default C library. CRuntime_Newlib is set when Newlib is the default C library. CRuntime_UClibc is set when uClibc is the default C library.

CppRuntime_Gcc

This version is defined when the standard C++ library being linked in is libstdc++.

D_BetterC

This version is defined when the standard D libraries are not being implicitly linked in. This also implies that features of the D language that rely on exceptions, module information, or run-time type information are disabled as well. Enabled by -fno-druntime.

D_Coverage

This version is defined when code coverage analysis instrumentation is being generated. Enabled by -ftest-coverage.

D_Ddoc

This version is defined when Ddoc documentation is being generated. Enabled by -fdoc.

D_Exceptions

This version is defined when exception handling is supported. Disabled by -fno-exceptions.

D_HardFloat

D_SoftFloat

These versions reflect the floating-point ABI in use by the target. D_HardFloat is set when the target hardware has a floating-point unit. D_SoftFloat is set when the target hardware does not have a floating-point unit.

D_Invariants

This version is defined when checks are being emitted for class invariants and struct invariants. Enabled by -finvariants.

D_LP64

This version is defined when pointers are 64-bits. Not to be confused with with C’s __LP64__ model.

D_ModuleInfo

This version is defined when run-time module information (also known as ModuleInfo) is supported. Disabled by -fno-moduleinfo.

D_NoBoundsChecks

This version is defined when array bounds checks are disabled. Enabled by -fno-bounds-checks.

D_Optimized

This version is defined in all optimizing compilations.

D_PIC

This version is defined when position-independent code is being generated. Enabled by -fPIC.

D_PIE

This version is defined when position-independent code that can be only linked into executables is being generated. Enabled by -fPIE.

D_PreConditions

This version is defined when checks are being emitted for in contracts. Disabled by -fno-preconditions.

D_PostConditions

This version is defined when checks are being emitted for out contracts. Disabled by -fno-postconditions.

D_TypeInfo

This version is defined when run-time type information (also known as TypeInfo) is supported. Disabled by -fno-rtti.

D_Version2

This version defined when this is a D version 2 compiler.

unittest

This version is defined when the unittest code is being compiled in. Enabled by -funittest.