Fix typecheck-only issues with #load in scripts (#19048)

Author: Copilot

docs/release-notes/.FSharp.Compiler.Service/11.0.0.md

@@ -13,6 +13,7 @@
 * Fix race in graph checking of type extensions. ([PR #19062](https://github.com/dotnet/fsharp/pull/19062))
 * Type relations cache: handle unsolved type variables ([Issue #19037](https://github.com/dotnet/fsharp/issues/19037)) ([PR #19040](https://github.com/dotnet/fsharp/pull/19040))
 * Fix insertion context for modules with multiline attributes. ([Issue #18671](https://github.com/dotnet/fsharp/issues/18671))
+* Fix `--typecheck-only` for scripts stopping after processing `#load`-ed script ([PR #19048](https://github.com/dotnet/fsharp/pull/19048))
 
 ### Added
 

src/Compiler/Interactive/fsi.fs

@@ -2223,46 +2223,50 @@ type internal FsiDynamicCompiler
                     inputs
                 ))
 
-        // typeCheckOnly either reports all errors found so far or exits with 0 - it stops processing the script
+        // typeCheckOnly: check for errors and skip code generation
         if tcConfig.typeCheckOnly then
+            // Always abort on errors (for both loaded files and main script)
             diagnosticsLogger.AbortOnError(fsiConsoleOutput)
-            raise StopProcessing
+            // Update state with type-checking results but skip code generation
+            let newIState = { istate with tcState = tcState }
 
-        let codegenResults, optEnv, fragName =
-            ProcessTypedImpl(
-                diagnosticsLogger,
-                optEnv,
-                tcState,
-                tcConfig,
-                isInteractiveItExpr,
-                topCustomAttrs,
-                prefixPath,
-                isIncrementalFragment,
-                declaredImpls,
-                ilxGenerator
-            )
+            newIState, tcEnvAtEndOfLastInput, []
+        else
+            let codegenResults, optEnv, fragName =
+                ProcessTypedImpl(
+                    diagnosticsLogger,
+                    optEnv,
+                    tcState,
+                    tcConfig,
+                    isInteractiveItExpr,
+                    topCustomAttrs,
+                    prefixPath,
+                    isIncrementalFragment,
+                    declaredImpls,
+                    ilxGenerator
+                )
 
-        let newState, declaredImpls =
-            ProcessCodegenResults(
-                ctok,
-                diagnosticsLogger,
-                istate,
-                optEnv,
-                tcState,
-                tcConfig,
-                prefixPath,
-                showTypes,
-                isIncrementalFragment,
-                fragName,
-                declaredImpls,
-                ilxGenerator,
-                codegenResults,
-                m
-            )
+            let newState, declaredImpls =
+                ProcessCodegenResults(
+                    ctok,
+                    diagnosticsLogger,
+                    istate,
+                    optEnv,
+                    tcState,
+                    tcConfig,
+                    prefixPath,
+                    showTypes,
+                    isIncrementalFragment,
+                    fragName,
+                    declaredImpls,
+                    ilxGenerator,
+                    codegenResults,
+                    m
+                )
 
-        CheckEntryPoint istate.tcGlobals declaredImpls
+            CheckEntryPoint istate.tcGlobals declaredImpls
 
-        (newState, tcEnvAtEndOfLastInput, declaredImpls)
+            (newState, tcEnvAtEndOfLastInput, declaredImpls)
 
     let tryGetGeneratedValue istate cenv v =
         match istate.ilxGenerator.LookupGeneratedValue(valuePrinter.GetEvaluationContext(istate.emEnv), v) with

tests/FSharp.Compiler.ComponentTests/Scripting/TypeCheckOnlyTests.fs

@@ -1,9 +1,28 @@
 module FSharp.Compiler.ComponentTests.Scripting.TypeCheckOnlyTests
 
+open System
+open System.IO
 open Xunit
 open FSharp.Test
 open FSharp.Test.Compiler
 
+let private withTempDirectory (test: string -> unit) =
+    let tempDir = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName())
+    Directory.CreateDirectory(tempDir) |> ignore
+
+    try
+        test tempDir
+    finally
+        try
+            if Directory.Exists(tempDir) then
+                Directory.Delete(tempDir, true)
+        with _ -> ()
+
+let private writeScript (dir: string) (filename: string) (content: string) =
+    let path = Path.Combine(dir, filename)
+    File.WriteAllText(path, content)
+    path
+
 [<Fact>]
 let ``typecheck-only flag works for valid script``() =
     Fsx """
@@ -44,4 +63,50 @@ let x = 21+21
     |> withOptions ["--nologo"]
     |> runFsi
     |> shouldSucceed
-    |> verifyOutputContains [|"val x: int = 42"|]
+    |> verifyOutputContains [|"val x: int = 42"|]
+
+[<Fact>]
+let ``typecheck-only flag catches type errors in scripts with #load``() =
+    withTempDirectory (fun tempDir ->
+        let domainPath = writeScript tempDir "Domain.fsx" "type T = {\n    Field: string\n}\n\nprintfn \"printfn Domain.fsx\""
+        
+        let mainContent = sprintf "#load \"%s\"\n\nopen Domain\n\nlet y = {\n    Field = 1\n}\n\nprintfn \"printfn A.fsx\"" (domainPath.Replace("\\", "\\\\"))
+        let mainPath = writeScript tempDir "A.fsx" mainContent
+        
+        FsxFromPath mainPath
+        |> withOptions ["--typecheck-only"]
+        |> runFsi
+        |> shouldFail
+        |> withStdErrContains "This expression was expected to have type"
+        |> ignore)
+
+[<Fact>]
+let ``typecheck-only flag catches type errors in loaded file``() =
+    withTempDirectory (fun tempDir ->
+        let domainPath = writeScript tempDir "Domain.fsx" "type T = { Field: string }\nlet x: int = \"error\"\nprintfn \"D\""
+        
+        let mainContent = sprintf "#load \"%s\"\nopen Domain\nlet y = { Field = \"ok\" }\nprintfn \"A\"" (domainPath.Replace("\\", "\\\\"))
+        let mainPath = writeScript tempDir "A.fsx" mainContent
+        
+        FsxFromPath mainPath
+        |> withOptions ["--typecheck-only"]
+        |> runFsi
+        |> shouldFail
+        |> withStdErrContains "This expression was expected to have type"
+        |> ignore)
+
+[<Fact>]
+let ``typecheck-only flag prevents execution with #load``() =
+    withTempDirectory (fun tempDir ->
+        let domainPath = writeScript tempDir "Domain.fsx" "type T = { Field: string }\nprintfn \"Domain.fsx output\""
+
+        let mainContent = sprintf "#load \"%s\"\nopen Domain\nlet y = { Field = \"test\" }\nprintfn \"A.fsx output\"" (domainPath.Replace("\\", "\\\\"))
+        let mainPath = writeScript tempDir "A.fsx" mainContent
+
+        FsxFromPath mainPath
+        |> withOptions ["--typecheck-only"]
+        |> runFsi
+        |> shouldSucceed
+        |> verifyNotInOutput "Domain.fsx output"
+        |> verifyNotInOutput "A.fsx output"
+        |> ignore)