cppdraft_translate/cppdraft/stmt/jump.md

[stmt.jump]

# 8 Statements [[stmt]](./#stmt)

## 8.8 Jump statements [stmt.jump]

### [8.8.1](#general) General [[stmt.jump.general]](stmt.jump.general)

[1](#general-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L988)

Jump statements unconditionally transfer control[.](#general-1.sentence-1)

[jump-statement:](#nt:jump-statement "8.8.1 General [stmt.jump.general]")  
break ;  
continue ;  
return [*expr-or-braced-init-list*](dcl.init.general#nt:expr-or-braced-init-list "9.5.1 General [dcl.init.general]")opt ;  
[*coroutine-return-statement*](#nt:coroutine-return-statement "8.8.5 The co_­return statement [stmt.return.coroutine]")  
goto [*identifier*](lex.name#nt:identifier "5.11 Identifiers [lex.name]") ;

[2](#general-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1007)

[*Note [1](#general-note-1)*:

On exit from a scope (however accomplished), objects with [automatic storage
duration](basic.stc.auto "6.8.6.4 Automatic storage duration [basic.stc.auto]") that have been constructed in that scope are destroyed
in the reverse order of their construction ([[stmt.dcl]](stmt.dcl "8.10 Declaration statement"))[.](#general-2.sentence-1)

For temporaries, see [[class.temporary]](class.temporary "6.8.7 Temporary objects")[.](#general-2.sentence-2)

However, the program can be terminated (by callingstd​::​exit() orstd​::​abort() ([[support.start.term]](support.start.term "17.5 Startup and termination")), for example) without
destroying objects with automatic storage duration[.](#general-2.sentence-3)

— *end note*]

[*Note [2](#general-note-2)*:

A suspension of a coroutine ([[expr.await]](expr.await "7.6.2.4 Await")) is not considered to be an exit from a scope[.](#general-2.sentence-4)

— *end note*]

### [8.8.2](#stmt.break) The break statement [[stmt.break]](stmt.break)

[1](#stmt.break-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1031)

A break statement shall be enclosed by ([[stmt.pre]](stmt.pre "8.1 Preamble"))an [*iteration-statement*](stmt.iter.general#nt:iteration-statement "8.6.1 General [stmt.iter.general]") ([[stmt.iter]](stmt.iter "8.6 Iteration statements")),
an [*expansion-statement*](stmt.expand#nt:expansion-statement "8.7 Expansion statements [stmt.expand]") ([[stmt.expand]](stmt.expand "8.7 Expansion statements")), or
a switch statement ([[stmt.switch]](stmt.switch "8.5.3 The switch statement"))[.](#stmt.break-1.sentence-1)

The break statement causes
termination of the innermost such enclosing statement;
control passes to the statement following the
terminated statement, if any[.](#stmt.break-1.sentence-2)

### [8.8.3](#stmt.cont) The continue statement [[stmt.cont]](stmt.cont)

[1](#stmt.cont-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1046)

A continue statement shall be enclosed by ([[stmt.pre]](stmt.pre "8.1 Preamble"))an [*iteration-statement*](stmt.iter.general#nt:iteration-statement "8.6.1 General [stmt.iter.general]") or an [*expansion-statement*](stmt.expand#nt:expansion-statement "8.7 Expansion statements [stmt.expand]")[.](#stmt.cont-1.sentence-1)

If the innermost enclosing such statement X is an [*iteration-statement*](stmt.iter.general#nt:iteration-statement "8.6.1 General [stmt.iter.general]") ([[stmt.iter]](stmt.iter "8.6 Iteration statements")),
the continue statement
causes control to pass to the end of the [*statement*](stmt.pre#nt:statement "8.1 Preamble [stmt.pre]") or [*compound-statement*](stmt.block#nt:compound-statement "8.4 Compound statement or block [stmt.block]") of X[.](#stmt.cont-1.sentence-2)

Otherwise, control passes to the end of the [*compound-statement*](stmt.block#nt:compound-statement "8.4 Compound statement or block [stmt.block]") of the current Si ([[stmt.expand]](stmt.expand "8.7 Expansion statements"))[.](#stmt.cont-1.sentence-3)

### [8.8.4](#stmt.return) The return statement [[stmt.return]](stmt.return)

[1](#stmt.return-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1063)

A function returns control to its caller by the return statement[.](#stmt.return-1.sentence-1)

[2](#stmt.return-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1066)

The [*expr-or-braced-init-list*](dcl.init.general#nt:expr-or-braced-init-list "9.5.1 General [dcl.init.general]") of a return statement is called its operand[.](#stmt.return-2.sentence-1)

A return statement with
no operand shall be used only in a function whose return type iscv void, a constructor ([[class.ctor]](class.ctor "11.4.5 Constructors")), or a
destructor ([[class.dtor]](class.dtor "11.4.7 Destructors"))[.](#stmt.return-2.sentence-2)

A return statement with an operand of type void shall be used only
in a function that has a cv void return type[.](#stmt.return-2.sentence-3)

A return statement with any other operand shall be used only
in a function that has a return type other than cv void;the return statement initializes the
returned reference or prvalue result object
of the (explicit or implicit) function call
by [copy-initialization](dcl.init#def:copy-initialization "9.5 Initializers [dcl.init]") from the operand[.](#stmt.return-2.sentence-4)

[*Note [1](#stmt.return-note-1)*:

A constructor or destructor does not have a return type[.](#stmt.return-2.sentence-5)

— *end note*]

[*Note [2](#stmt.return-note-2)*:

A return statement can involve
an invocation of a constructor to perform a copy or move of the operand
if it is not a prvalue or if its type differs from the return type of the function[.](#stmt.return-2.sentence-6)

A copy operation associated with a return statement can be elided or
converted to a move operation if an automatic storage duration variable is returned ([[class.copy.elision]](class.copy.elision "11.9.6 Copy/move elision"))[.](#stmt.return-2.sentence-7)

— *end note*]

[3](#stmt.return-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1094)

The destructor for the result object
is potentially invoked ([[class.dtor]](class.dtor "11.4.7 Destructors"), [[except.ctor]](except.ctor "14.3 Stack unwinding"))[.](#stmt.return-3.sentence-1)

[*Example [1](#stmt.return-example-1)*: class A {~A() {}};
A f() { return A(); } // error: destructor of A is private (even though it is never invoked) — *end example*]

[4](#stmt.return-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1106)

Flowing off the end of
a constructor,
a destructor, or
a non-coroutine function with a cv void return type is
equivalent to a return with no operand[.](#stmt.return-4.sentence-1)

Otherwise, flowing off the end of a function
that is neither main ([[basic.start.main]](basic.start.main "6.10.3.1 main function")) nor a coroutine ([[dcl.fct.def.coroutine]](dcl.fct.def.coroutine "9.6.4 Coroutine definitions"))
results in undefined behavior[.](#stmt.return-4.sentence-2)

[5](#stmt.return-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1116)

The copy-initialization of the result of the call is sequenced before the
destruction of temporaries at the end of the full-expression established
by the operand of the return statement, which, in turn, is sequenced
before the destruction of local variables ([stmt.jump]) of the block
enclosing the return statement[.](#stmt.return-5.sentence-1)

[*Note [3](#stmt.return-note-3)*:

These operations
are sequenced before the destruction of local variables
in each remaining enclosing block of the function ([[stmt.dcl]](stmt.dcl "8.10 Declaration statement")),
which, in turn,
is sequenced before the evaluation of
postcondition assertions of the function ([[dcl.contract.func]](dcl.contract.func "9.4.1 General")),
which, in turn,
is sequenced before the destruction of function parameters ([[expr.call]](expr.call "7.6.1.3 Function call"))[.](#stmt.return-5.sentence-2)

— *end note*]

[6](#stmt.return-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1133)

In a function whose return type is a reference,
other than an invented function for std​::​is_convertible ([[meta.rel]](meta.rel "21.3.8 Relationships between types")),
a return statement that binds the returned reference to
a temporary expression ([[class.temporary]](class.temporary "6.8.7 Temporary objects")) is ill-formed[.](#stmt.return-6.sentence-1)

[*Example [2](#stmt.return-example-2)*: auto&& f1() {return 42; // ill-formed}const double& f2() {static int x = 42; return x; // ill-formed}auto&& id(auto&& r) {return static_cast<decltype(r)&&>(r);}auto&& f3() {return id(42); // OK, but probably a bug} — *end example*]

### [8.8.5](#stmt.return.coroutine) The co_return statement [[stmt.return.coroutine]](stmt.return.coroutine)

[coroutine-return-statement:](#nt:coroutine-return-statement "8.8.5 The co_­return statement [stmt.return.coroutine]")  
co_return [*expr-or-braced-init-list*](dcl.init.general#nt:expr-or-braced-init-list "9.5.1 General [dcl.init.general]")opt ;

[1](#stmt.return.coroutine-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1165)

A co_return statement transfers control to
the caller or resumer of a coroutine ([[dcl.fct.def.coroutine]](dcl.fct.def.coroutine "9.6.4 Coroutine definitions"))[.](#stmt.return.coroutine-1.sentence-1)

A coroutine shall not enclose
a return statement ([[stmt.return]](#stmt.return "8.8.4 The return statement"))[.](#stmt.return.coroutine-1.sentence-2)

[*Note [1](#stmt.return.coroutine-note-1)*:

For this determination, it is irrelevant whether the return statement
is enclosed by a discarded statement ([[stmt.if]](stmt.if "8.5.2 The if statement"))[.](#stmt.return.coroutine-1.sentence-3)

— *end note*]

[2](#stmt.return.coroutine-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1175)

The [*expr-or-braced-init-list*](dcl.init.general#nt:expr-or-braced-init-list "9.5.1 General [dcl.init.general]") of a co_return statement is
called its operand[.](#stmt.return.coroutine-2.sentence-1)

Let *p* be an lvalue naming the coroutine
promise object ([[dcl.fct.def.coroutine]](dcl.fct.def.coroutine "9.6.4 Coroutine definitions"))[.](#stmt.return.coroutine-2.sentence-2)

A co_return statement is equivalent to:

{ S; goto *final-suspend*; }

where *final-suspend* is the exposition-only label
defined in [[dcl.fct.def.coroutine]](dcl.fct.def.coroutine "9.6.4 Coroutine definitions") and *S* is defined as follows:

- [(2.1)](#stmt.return.coroutine-2.1)

  If the operand is a [*braced-init-list*](dcl.init.general#nt:braced-init-list "9.5.1 General [dcl.init.general]") or an expression of non-void type,*S* is *p*.return_value([*expr-or-braced-init-list*](dcl.init.general#nt:expr-or-braced-init-list "9.5.1 General [dcl.init.general]"))[.](#stmt.return.coroutine-2.1.sentence-1)
  The expression *S* shall be a prvalue of type void[.](#stmt.return.coroutine-2.1.sentence-2)

- [(2.2)](#stmt.return.coroutine-2.2)

  Otherwise,*S* is the [*compound-statement*](stmt.block#nt:compound-statement "8.4 Compound statement or block [stmt.block]") { [*expression*](expr.comma#nt:expression "7.6.20 Comma operator [expr.comma]")opt ; *p*.return_void(); }[.](#stmt.return.coroutine-2.2.sentence-1)
  The expression *p*.return_void() shall be a prvalue of type void[.](#stmt.return.coroutine-2.2.sentence-2)

[3](#stmt.return.coroutine-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1200)

If a search for the name return_void in the scope of the promise type
finds any declarations,
flowing off the end of a coroutine's [*function-body*](dcl.fct.def.general#nt:function-body "9.6.1 General [dcl.fct.def.general]") is equivalent to a co_return with no operand;
otherwise flowing off the end of a coroutine's [*function-body*](dcl.fct.def.general#nt:function-body "9.6.1 General [dcl.fct.def.general]") results in undefined behavior[.](#stmt.return.coroutine-3.sentence-1)

### [8.8.6](#stmt.goto) The goto statement [[stmt.goto]](stmt.goto)

[1](#stmt.goto-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L1211)

The goto statement unconditionally transfers control to the
statement labeled by the identifier[.](#stmt.goto-1.sentence-1)

The identifier shall be a[label](stmt.label "8.2 Label [stmt.label]") located in the current function[.](#stmt.goto-1.sentence-2)