never used.
</p>

<h3 id="Short_variable_declarations">Short variable declarations</h3>

<p>
A <i>short variable declaration</i> uses the syntax:
</p>

<pre class="ebnf">
ShortVarDecl = IdentifierList ":=" ExpressionList .
</pre>

<p>
It is shorthand for a regular <a href="#Variable_declarations">variable declaration</a>
with initializer expressions but no types:
</p>

more specific CC_FOR_${GOOS}_${GOARCH} (for example, CC_FOR_linux_arm)
environment variable when building the toolchain using make.bash,
or you can set the CC environment variable any time you run the go tool.

The CXX_FOR_TARGET, CXX_FOR_${GOOS}_${GOARCH}, and CXX
environment variables work in a similar way for C++ code.

# Go references to C

never used.
</p>

<h3 id="Short_variable_declarations">Short variable declarations</h3>

<p>
A <i>short variable declaration</i> uses the syntax:
</p>

<pre class="ebnf">
ShortVarDecl = IdentifierList ":=" ExpressionList .
</pre>

<p>
It is shorthand for a regular <a href="#Variable_declarations">variable declaration</a>
with initializer expressions but no types:
</p>

reduce the impact such changes have on Go developers
using newer toolchains to compile old code.

A GODEBUG setting is a `key=value` pair
that controls the execution of certain parts of a Go program.
The environment variable `GODEBUG`
can hold a comma-separated list of these settings.
For example, if a Go program is running in an environment that contains

	GODEBUG=http2client=0,http2server=0

//go:build cgo

package cgotest

import (
	"testing"

	"cmd/cgo/internal/test/gcc68255"
)

func testGCC68255(t *testing.T) {
	if !gcc68255.F() {
		t.Error("C global variable was not initialized")
	}

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test that it's OK to have C code that does nothing other than
// initialize a global variable.  This used to fail with gccgo.

package gcc68255

/*
#include "c.h"
*/
import "C"

func F() bool {
	return C.v != nil

	RET
TEXT ·a8(SB), 0, $0-0
	CMPL runtime·writeBarrier(SB), $0
	ADDQ AX, R15 // ERROR "when dynamic linking, R15 is clobbered by a global variable access and is used here"
	RET
TEXT ·a9(SB), 0, $0-0
	CMPL runtime·writeBarrier(SB), $0
	ORQ R15, R15 // ERROR "when dynamic linking, R15 is clobbered by a global variable access and is used here"
	RET

// sufficient to initialize a [Buffer].
func NewBuffer(buf []byte) *Buffer { return &Buffer{buf: buf} }

// NewBufferString creates and initializes a new [Buffer] using string s as its
// initial contents. It is intended to prepare a buffer to read an existing
// string.
//
// In most cases, new([Buffer]) (or just declaring a [Buffer] variable) is
// sufficient to initialize a [Buffer].

// (booleans, numbers, strings, pointers, channels, arrays of comparable types,
// structs whose fields are all comparable types).
// The comparable interface may only be used as a type parameter constraint,
// not as the type of a variable.
type comparable interface{ comparable }

// iota is a predeclared identifier representing the untyped integer ordinal
// number of the current const specification in a (usually parenthesized)

			}
			n.Define = val
		}
	}
}

// guessKinds tricks gcc into revealing the kind of each
// name xxx for the references C.xxx in the Go input.
// The kind is either a constant, type, or variable.
func (p *Package) guessKinds(f *File) []*Name {
	// Determine kinds for names we already know about,
	// like #defines or 'struct foo', before bothering with gcc.
	var names, needType []*Name