From 05b831982d39377a1b30017e0196b24d1543d29a Mon Sep 17 00:00:00 2001
From: Tomas Grosup <tomasgrosup@microsoft.com>
Date: Wed, 25 Feb 2026 18:58:37 +0100
Subject: [PATCH] DotNetBuildUseMonoRuntime stackguard

---
 azure-pipelines-PR.yml                            |  3 +++
 .../Driver/GraphChecking/FileContentMapping.fs    | 15 ++++++++++++++-
 src/Compiler/FSharp.Compiler.Service.fsproj       |  1 +
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/azure-pipelines-PR.yml b/azure-pipelines-PR.yml
index d775d9ed907..3c13a6899bf 100644
--- a/azure-pipelines-PR.yml
+++ b/azure-pipelines-PR.yml
@@ -207,6 +207,9 @@ stages:
           - name: 'Managed'
             container: 'mcr.microsoft.com/dotnet-buildtools/prereqs:centos-stream9'
             buildArguments: '--source-build'
+          - name: 'Managed_MonoRuntime'
+            container: 'mcr.microsoft.com/dotnet-buildtools/prereqs:centos-stream9'
+            buildArguments: '--source-build /p:DotNetBuildUseMonoRuntime=true'
         enableTelemetry: true
         helixRepo: dotnet/fsharp
         jobs:
diff --git a/src/Compiler/Driver/GraphChecking/FileContentMapping.fs b/src/Compiler/Driver/GraphChecking/FileContentMapping.fs
index 12881a8dbe2..26c73f8e96f 100644
--- a/src/Compiler/Driver/GraphChecking/FileContentMapping.fs
+++ b/src/Compiler/Driver/GraphChecking/FileContentMapping.fs
@@ -2,6 +2,7 @@
 
 open FSharp.Compiler.Syntax
 open FSharp.Compiler.SyntaxTreeOps
+open FSharp.Compiler.DiagnosticsLogger
 
 type Continuations = ((FileContentEntry list -> FileContentEntry list) -> FileContentEntry list) list
 
@@ -362,7 +363,16 @@ let (|NameofExpr|_|) (e: SynExpr) : NameofResult voption =
     | _ -> ValueNone
 
 let visitSynExpr (e: SynExpr) : FileContentEntry list =
+#if BUILD_USING_MONO
+    let rec visitGuarded
+        (sg: StackGuard)
+        (e: SynExpr)
+        (continuation: FileContentEntry list -> FileContentEntry list)
+        : FileContentEntry list =
+        let visit e c = sg.Guard(fun () -> visitGuarded sg e c)
+#else
     let rec visit (e: SynExpr) (continuation: FileContentEntry list -> FileContentEntry list) : FileContentEntry list =
+#endif
         match e with
         | NameofExpr nameofResult -> continuation [ visitNameofResult nameofResult ]
         | SynExpr.Const _ -> continuation []
@@ -559,8 +569,11 @@ let visitSynExpr (e: SynExpr) : FileContentEntry list =
         | SynExpr.Dynamic(funcExpr, _, argExpr, _) ->
             let continuations = List.map visit [ funcExpr; argExpr ]
             Continuation.concatenate continuations continuation
-
+#if BUILD_USING_MONO
+    visitGuarded (StackGuard(nameof (FileContentMapping))) e id
+#else
     visit e id
+#endif
 
 /// Special case of `| nameof Module ->` type of pattern
 [<return: Struct>]
diff --git a/src/Compiler/FSharp.Compiler.Service.fsproj b/src/Compiler/FSharp.Compiler.Service.fsproj
index cc8865d2578..5b1d11f9242 100644
--- a/src/Compiler/FSharp.Compiler.Service.fsproj
+++ b/src/Compiler/FSharp.Compiler.Service.fsproj
@@ -14,6 +14,7 @@
     <AssemblyName>FSharp.Compiler.Service</AssemblyName>
     <AllowCrossTargeting>true</AllowCrossTargeting>
     <DefineConstants>$(DefineConstants);COMPILER</DefineConstants>
+	<DefineConstants Condition="$(DotNetBuildUseMonoRuntime) == 'true'">$(DefineConstants);BUILD_USING_MONO</DefineConstants>
 	<Nullable>enable</Nullable>
 	<!-- Nullness checking against ns20 base class libraries is very weak, the APIs were not updated with annotations.
 	     Therefore we want to use the latest BCL APIs from NetCurrent.