Unreachable Code (UnreachableCode)¶

Type	Scope	Severity	Activated by default	Minutes to fix	Tags
`Error`	`BSL` `OS`	`Minor`	`Yes`	`10`	`design` `suspicious` `unused`

Description¶

Code located after operators "Return", "GoTo", "Raise", "Break", "Continue" never will be executed.

Errors of unreachable code can be caused by developer carelessness when editing another's code.

The diagnostic also detects preprocessor branches that are impossible for every admissible combination of symbols. Enclosing conditions and preceding #If / #ElsIf / #Else alternatives are taken into account.

For BSL, the module contexts and the method's compilation directive are also considered. By default, #If Server and #If Server And Client branches are unreachable inside a client method of a managed form. Enabling the shared supportThickClientFileMode setting includes the file-mode thick client, where both Client and Server can be true, including inside a client form method. Unknown metadata does not restrict availability beyond the modes supported by the project. Context-selection settings of other diagnostics do not affect this check.

In BSL, assignments and returns excluded by compilation contexts do not contribute to inferred types. After a #If Server And Not Server branch assigning a number and an #Else branch assigning a string, the variable has only the String type. Repeating #If Client selects values from the earlier client branch, including values copied through intermediate variables.

For OneScript, exactly one of Windows, Linux, and MacOS is active; MONO is an independent additional symbol. A Linux branch nested inside Windows, or a Windows And Linux condition, is unreachable. Host-defined symbols remain conservative: a branch is excluded only when its condition is provably impossible.

The whole excluded branch is highlighted, including method declarations, comments, and nested regions. Overlapping findings are merged. Diagnostics carry the LSP Unnecessary tag so that editors can dim unreachable code.

Incomplete or malformed preprocessor directives are not used to prove unreachability. A finding is emitted only when the condition has been proved impossible.

Examples¶

The following branch is never compiled:

#If Server And Not Server Then
Procedure Unavailable()
    Message("This code is excluded");
EndProcedure
#EndIf

Procedure Example()
    Return;
    // Code below operator Return will never be executed
    For each Line from Lines Do
        If Condition2 Then
            Method();
        EndIf;
    EndDo;
EndProcedure

Function Example(Parameter1, Parameter2)
    If Error Then
        Raise "Error occurred";
        // After rise exception the code bellow will be ignored
        Parameter1 = Parameter2;
    EndIf; 
    Return Parameter1;
EndFunction

Snippets¶

Diagnostic ignorance in code¶

// BSLLS:UnreachableCode-off
// BSLLS:UnreachableCode-on

Parameter for config¶

"UnreachableCode": false