pkg debug/elf, const DT_MIPS_PROTECTED_GOTIDX DynTag
pkg debug/elf, const DT_MIPS_RLD_MAP = 1879048214
pkg debug/elf, const DT_MIPS_RLD_MAP DynTag
pkg debug/elf, const DT_MIPS_RLD_MAP_REL = 1879048245
pkg debug/elf, const DT_MIPS_RLD_MAP_REL DynTag
pkg debug/elf, const DT_MIPS_RLD_TEXT_RESOLVE_ADDR = 1879048237
pkg debug/elf, const DT_MIPS_RLD_TEXT_RESOLVE_ADDR DynTag
pkg debug/elf, const DT_MIPS_RLD_VERSION = 1879048193

pkg net/rpc, type Call struct
pkg net/rpc, type Call struct, Args interface{}
pkg net/rpc, type Call struct, Done chan *Call
pkg net/rpc, type Call struct, Error error
pkg net/rpc, type Call struct, Reply interface{}
pkg net/rpc, type Call struct, ServiceMethod string
pkg net/rpc, type Client struct
pkg net/rpc, type ClientCodec interface { Close, ReadResponseBody, ReadResponseHeader, WriteRequest }

---
title: "Go, Backwards Compatibility, and GODEBUG"
layout: article
---

<!--
This document is kept in the Go repo, not x/website,
because it documents the full list of known GODEBUG settings,
which are tied to a specific release.
-->

## Introduction {#intro}

Go's emphasis on backwards compatibility is one of its key strengths.
There are, however, times when we cannot maintain complete compatibility.

	// FullRune distinguishes correctly between erroneous and incomplete encodings.
	if !atEOF && !utf8.FullRune(data) {
		// Incomplete; get more bytes.
		return 0, nil, nil
	}

	// We have a real UTF-8 encoding error. Return a properly encoded error rune
	// but advance only one byte. This matches the behavior of a range loop over
	// an incorrectly encoded string.
	return 1, errorRune, nil
}

glob "*stdlib/*minor" are treated specially. They should be in subdirectories
corresponding to standard library package paths, and headings for those package
paths will be generated automatically.

Files in this repo's `api/next` directory must have corresponding files in
`doc/next/*stdlib/*minor`.
The files should be in the subdirectory for the package with the new
API, and should be named after the issue number of the API proposal.

// floating-point values. The real and imaginary parts must be of the same
// size, either float32 or float64 (or assignable to them), and the return
// value will be the corresponding complex type (complex64 for float32,
// complex128 for float64).
func complex(r, i FloatType) ComplexType

// The real built-in function returns the real part of the complex number c.

are predefined and refer to registers.
The exact set depends on the architecture.
</p>

<p>
There are four predeclared symbols that refer to pseudo-registers.
These are not real registers, but rather virtual registers maintained by
the toolchain, such as a frame pointer.
The set of pseudo-registers is the same for all architectures:
</p>

<ul>

<li>

The built-in function <code>complex</code> constructs a complex
value from a floating-point real and imaginary part, while
<code>real</code> and <code>imag</code>
extract the real and imaginary parts of a complex value.
</p>

<pre class="grammar">
complex(realPart, imaginaryPart floatT) complexT
real(complexT) floatT
imag(complexT) floatT
</pre>

<p>

pkg debug/elf, const DT_PLTGOT = 3
pkg debug/elf, const DT_PLTREL = 20
pkg debug/elf, const DT_PLTRELSZ = 2
pkg debug/elf, const DT_PREINIT_ARRAY = 32
pkg debug/elf, const DT_PREINIT_ARRAYSZ = 33
pkg debug/elf, const DT_REL = 17
pkg debug/elf, const DT_RELA = 7
pkg debug/elf, const DT_RELAENT = 9
pkg debug/elf, const DT_RELASZ = 8
pkg debug/elf, const DT_RELENT = 19
pkg debug/elf, const DT_RELSZ = 18
pkg debug/elf, const DT_RPATH = 15

# Treat all files in the Go repo as binary, with no git magic updating
# line endings. This produces predictable results in different environments.
#
# Windows users contributing to Go will need to use a modern version
# of git and editors capable of LF line endings.
#
# Windows .bat files are known to have multiple bugs when run with LF
# endings, and so they are checked in with CRLF endings, with a test