Fix wrong warning 20 range in sequential expressions (#5735)#19504
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Fix wrong warning 20 range in sequential expressions (#5735)#19504
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Fixed in 36f51b6. The root cause was that |
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Fix wrong warning 20 range in sequential expressions (#5735)
Mar 31, 2026
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In TcStmt, the range used for warning 20 was synExpr.Range which, for sequential expressions (e.g. loop bodies with multiple statements), covered the entire body. This made the squiggle highlight the whole block instead of just the offending non-unit expression. Added lastExprRange helper that walks the SynExpr.Sequential chain to find the range of the last expression, so the warning now correctly points at only the expression that produces the ignored value. Added 4 regression tests for for-in, for-to, and while loops. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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FSharp.Core 11.0.100 and FSharp.Compiler.Service 43.12.100 are already published on NuGet, causing Check_Published_Package_Versions CI checks to fail. Bump to 101 to match other active PRs targeting main. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Fixes the "expression is implicitly ignored" (warning 20) squiggle pointing at the wrong range when the last expression in a sequential block (e.g. inside
for,whileloops) is non-unit.Root Cause
In
TcStmt, the rangemwas set tosynExpr.Rangewhich, for a sequential expression like a loop body with multiple statements, covered the entire body. When the non-unit type warning was emitted, it used this overly broad range. Thebooltype case was already handled correctly byReportImplicitlyIgnoredBoolExpressionwhich walks the typed expression tree, but non-bool types (int, string, etc.) used the wrong range.Changes Made
src/Compiler/Checking/Expressions/CheckExpressions.fs— Added alastExprRangehelper that walks theSynExpr.Sequentialchain to find the range of the last expression, and used it inTcStmtinstead ofsynExpr.Range.tests/FSharp.Compiler.ComponentTests/ErrorMessages/WarnExpressionTests.fs— Added 4 regression tests coveringfor-in,for-to, andwhileloops with non-unit last expressions (int, string types).docs/release-notes/.FSharp.Compiler.Service/11.0.100.md— Added release note entry.Testing
Warn Expressiontests pass (12 existing + 4 new)CustomAttributestests unaffected🔒 GitHub Advanced Security automatically protects Copilot coding agent pull requests. You can protect all pull requests by enabling Advanced Security for your repositories. Learn more about Advanced Security.