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Fix CFG builder crash on preprocessor directives spanning elsif boundaries#3823

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Fix CFG builder crash on preprocessor directives spanning elsif boundaries#3823
Copilot wants to merge 2 commits intodevelopfrom
copilot/fix-diagnostic-computation-error-again

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Copilot AI commented Feb 17, 2026 •
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Both UnreachableCode and AllFunctionPathMustHaveReturn diagnostics throw Diagnostic computation error when preprocessor #Если/#КонецЕсли spans across ИначеЕсли boundaries, causing the CFG builder's block stack to become unbalanced.

Pattern that triggers the crash:

Если КлассОМ = "ПЛАНОБМЕНА" Тогда
    Менеджер = ПланыОбмена;
#Если НЕ МобильноеПриложениеСервер Тогда
ИначеЕсли КлассОМ = "ОТЧЕТ" Тогда
    Менеджер = Отчеты;
#КонецЕсли
КонецЕсли;

visitPreproc_if enters two blocks that visitPreproc_endif never leaves (the #КонецЕсли is in a different codeBlock), corrupting the stack → NoSuchElementException / FlowGraphLinkException.

Changes

  • CfgBuildingParseTreeVisitor.visitPreproc_if() — added hasMatchingEndIfInSameCodeBlock() guard; when unbalanced, skip CFG node creation and fall back to super.visitPreproc_if(ctx)
  • hasMatchingEndIfInSameCodeBlock() — new helper that walks sibling statements in the enclosing codeBlock, tracking #Если/#КонецЕсли nesting depth to verify balance
  • UnreachableCodeDiagnosticTest — added test with the exact crash pattern (preprocessor wrapping elsif branches + early Возврат)
Original prompt

This section details on the original issue you should resolve

<issue_title>[BUG] Diagnostic computation error при проверке UnreachableCode</issue_title>
<issue_description>## Диагностика
UnreachableCode

Версия

BSLLS v0.28.4 (расширение 1c-syntax.language-1c-bsl для VS Code)

Описание ошибки диагностики

При анализе модуля адаптер_ОбщегоНазначенияСервер/Ext/Module.bsl вместо результата проверки UnreachableCode возникает Diagnostic computation error:

[ERROR] [diagnostic-computer] [com.github._1c_syntax.bsl.languageserver.context.computer.DiagnosticComputer]: Diagnostic computation error.
File: file:///.../адаптер_ОбщегоНазначенияСервер/Ext/Module.bsl
Diagnostic: Either [
  left = UnreachableCode
  right = null
]

Пример кода

Процедура Ожидание с ранним Возврат и заведомо недостижимым кодом:

Процедура Ожидание(Компонента, Секунд) Экспорт

	// Нетиповое{ ПервыйБИТ Латышева Н.А.  12.03.2024 VTRD-724
	// #ОтказОтSleep
	Возврат;
	// Нетиповое} ПервыйБИТ Латышева Н.А.  12.03.2024 VTRD-724	
	
	Если ТипЗнч(Компонента) = Тип("ОбработкаОбъект.адаптер_КомпонентаRabbitMQ") Тогда
		Компонента.Ожидание(Секунд * 1000);
	Иначе
		Компонента.Sleep(Секунд * 1000);
	КонецЕсли;
	
КонецПроцедуры

Скриншоты

WARNING: A terminally deprecated method in sun.misc.Unsafe has been called
WARNING: sun.misc.Unsafe::objectFieldOffset has been called by org.ehcache.impl.internal.concurrent.ThreadLocalRandomUtil (jar:nested:/C:/Users/ikarl/AppData/Roaming/Cursor/User/globalStorage/1c-syntax.language-1c-bsl/bsl-language-server/v0.28.4/bsl-language-server/app/bsl-language-server-0.28.4-exec.jar/!BOOT-INF/lib/ehcache-3.11.1.jar!/)
WARNING: Please consider reporting this to the maintainers of class org.ehcache.impl.internal.concurrent.ThreadLocalRandomUtil
WARNING: sun.misc.Unsafe::objectFieldOffset will be removed in a future release
[Warn  - 11:31:10] [WARN - 2026-02-17T08:31:04.567399600Z] [compute-configuration-7] [com.github._1c_syntax.bsl.reader.common.converter.ValueTypeConverter]: Parsing error due to unknown value type v8ui:ChartType. Please, create issue using link https://github.com/1c-syntax/mdclasses/issues/new?labels=bug&title=%5BBUG%5D%20Unknown%20valueType%20%5Bv8ui:ChartType%5D
[Warn  - 11:31:10] [WARN - 2026-02-17T08:31:04.850074800Z] [compute-configuration-12] [com.github._1c_syntax.bsl.reader.common.converter.ValueTypeConverter]: Parsing error due to unknown value type v8ui:HorizontalAlign. Please, create issue using link https://github.com/1c-syntax/mdclasses/issues/new?labels=bug&title=%5BBUG%5D%20Unknown%20valueType%20%5Bv8ui:HorizontalAlign%5D
[Warn  - 11:31:13] [WARN - 2026-02-17T08:31:06.703016400Z] [compute-configuration-6] [com.github._1c_syntax.bsl.reader.common.converter.ValueTypeConverter]: Parsing error due to unknown value type d7p1:FlowchartContextType. Please, create issue using link https://github.com/1c-syntax/mdclasses/issues/new?labels=bug&title=%5BBUG%5D%20Unknown%20valueType%20%5Bd7p1:FlowchartContextType%5D
[Error - 11:31:27] [ERROR - 2026-02-17T08:31:12.943362400Z] [diagnostic-computer-13] [com.github._1c_syntax.bsl.languageserver.context.computer.DiagnosticComputer]: Diagnostic computation error.
File: file:///C:/Users/ikarl/git/git.ventra.local/Ventra-1C/bit.finance/src/cfe/БИТАдаптер/CommonModules/адаптер_ОбщегоНазначенияСервер/Ext/Module.bsl
Diagnostic: Either [
  left = AllFunctionPathMustHaveReturn
  right = null
]
[Error - 11:31:29] [ERROR - 2026-02-17T08:31:12.970360400Z] [diagnostic-computer-26] [com.github._1c_syntax.bsl.languageserver.context.computer.DiagnosticComputer]: Diagnostic computation error.
File: file:///C:/Users/ikarl/git/git.ventra.local/Ventra-1C/bit.finance/src/cfe/БИТАдаптер/CommonModules/адаптер_ОбщегоНазначенияСервер/Ext/Module.bsl
Diagnostic: Either [
  left = UnreachableCode
  right = null
]
[Error - 11:47:43] [ERROR - 2026-02-17T08:47:43.252984900Z] [diagnostic-computer-45] [com.github._1c_syntax.bsl.languageserver.context.computer.DiagnosticComputer]: Diagnostic computation error.
File: file:///C:/Users/ikarl/git/git.ventra.local/Ventra-1C/bit.finance/src/cfe/БИТАдаптер/CommonModules/адаптер_ОбщегоНазначенияСервер/Ext/Module.bsl
Diagnostic: Either [
  left = AllFunctionPathMustHaveReturn
  right = null
]
[Error - 11:47:43] [ERROR - 2026-02-17T08:47:43.277982Z] [diagnostic-computer-48] [com.github._1c_syntax.bsl.languageserver.context.computer.DiagnosticComputer]: Diagnostic computation error.
File: file:///C:/Users/ikarl/git/git.ventra.local/Ventra-1C/bit.finance/src/cfe/БИТАдаптер/CommonModules/адаптер_ОбщегоНазначенияСервер/Ext/Module.bsl
Diagnostic: Either [
  left = UnreachableCode
  right = null
]

Дополнительная информация

  • Код после Возврат; (стр. 684) действительно недостижим.
  • BSLLS вместо отчёта UnreachableCode генерирует Diagnostic computation error.
  • Воспроизводится в VS Code и SonarQube.
  • Файл: src/cfe/БИТАдаптер/CommonModules/адаптер_ОбщегоНазначенияСервер/Ext/Module.bsl.

[Diagnostic error.z...

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@nixel2007
Fix CFG builder crash when preprocessor directives span across elsif …
503cf5b 
…boundaries

When a statement-level #Если in one elsif branch's codeBlock does not
have a matching #КонецЕсли in the same codeBlock (because it spans
across elsif boundaries), the CFG builder's block stack becomes
unbalanced, leading to NoSuchElementException or FlowGraphLinkException.

Add hasMatchingEndIfInSameCodeBlock() check to visitPreproc_if() to
detect unbalanced preprocessor blocks and skip CFG graph manipulation
for them, falling back to simple child visiting instead.

Fixes #3821

Co-authored-by: nixel2007 <1132840+nixel2007@users.noreply.github.com>
Copilot AI changed the title [WIP] Fix diagnostic computation error for UnreachableCode Fix CFG builder crash on preprocessor directives spanning elsif boundaries Feb 17, 2026
Copilot AI requested a review from nixel2007 February 17, 2026 18:23
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[BUG] Diagnostic computation error при проверке UnreachableCode

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