BSL148 - All execution paths of a function must have a Return statement¶

Summary¶

All execution paths of a function must have a Return statement

Identifiers¶

Field	Value
Rule code	`BSL148`
Compatible alias	`AllFunctionPathMustHaveReturn`
Severity	`ERROR`
Without configuration	Yes
BSLLS JSON, `ON` mode without overrides	Yes
Registry flag `implemented`	Yes
Tags	`error-handling`, `correctness`

The implemented flag describes the registry; it does not certify verified BSLLS parity.

Supported parameters¶

TOML	BSLLS JSON	Default
`bsl148-loops-executed-at-least-once`	`loopsExecutedAtLeastOnce`	`true`

TOML keys belong in [tool.onec-hbk-bsl]; JSON keys belong in diagnostics.parameters.AllFunctionPathMustHaveReturn.

Behavior¶

The public identifier BSL148 and alias AllFunctionPathMustHaveReturn are stable.
The rule reports the cases documented on this page.
Suppressions and project configuration are applied before publication.
The rule requires neither an external analyzer nor network access.

Configuration and suppression¶

BSL### is the primary stable identifier. The compatible alias is accepted in select, ignore, and compatible block suppression comments.

[tool.onec-hbk-bsl]
select = ["BSL148"]
ignore = ["AllFunctionPathMustHaveReturn"]

All three suppression families support both a current line and a range. When an opening comment follows code, it affects only that line. Use any one form:

noqa:

Value = "example";  // noqa: BSL148

bsl-disable:

Value = "example";  // bsl-disable: BSL148

compatible BSLLS form:

Value = "example";  // BSLLS:AllFunctionPathMustHaveReturn-off

When the same opening comment is on a line by itself, it starts a range. Close it with the matching marker from the same family:

// noqa: BSL148
// code without this diagnostic
// noqa-enable: BSL148

// bsl-disable: BSL148
// code without this diagnostic
// bsl-enable: BSL148

// BSLLS:AllFunctionPathMustHaveReturn-off
// code without this diagnostic
// BSLLS:AllFunctionPathMustHaveReturn-on

To disable the rule until the end of the file, omit the closing noqa-enable, bsl-enable, or BSLLS:…-on marker.

Opening and closing markers must belong to the same family.

Description¶

Functions should not have an implicit return. If control reaches the EndFunction line function returns an Undefined value.

As a rule, this is not a normal operation; the programmer must explicitly describe all return values of the function. However, it is quite easy to overlook a situation in which control reaches the EndFunction line and returns an unexpected Undefined value.

This diagnostics checks that all possible paths of the function execution have an explicit Return statement and the function does not return unexpected values.

Examples¶

Incorrect¶

// if the rate is full, but not Tax10 not Tax10 - returns Undefined
// this could be error or planned behavior.
Function DefineTaxRate(Val Rate)
    If Rate = Enums.TaxRates.Tax20 Then
        Return 20;
    ElsIf Rate = Enums.TaxRates.Tax10 Then
        Return 10;
    ElsIf Not ValueIsFilled(Rate) Then
        Return Constants.DefaultTaxRate.Get();
    EndIf;

    // implicit return Undefined
EndFunction

Correct¶

// explicitly specify the intention to return the result in the end of the function.
Function DefineTaxRate(Val Rate)
    If Rate = Enums.TaxRates.Tax20 Then
        Return 20;
    ElsIf Rate = Enums.TaxRates.Tax10 Then
        Return 10;
    ElsIf Not ValueIsFilled(Rate) Then
        Return Constants.DefaultTaxRate.Get();
    EndIf;

    // explicit return
    Return Undefined;
EndFunction

Another example of incorrect code:¶

Function DiscountAmount(Val OrderBasket)
    If OrderBasket.Rows.Count() > 10 Then
        Return Discounts.DiscountOnBigBasket(OrderBasket);
    ElsIf OrderBasket.IsCustomerCard Then
        // function returns an unintended value is Undefined
        Discounts.DiscountByCustomerCard(OrderBasket);
    Else
        Return 0;
    EndIf;
EndFunction