From fd85f6c35a113bc68cad2be61c97613b7f745933 Mon Sep 17 00:00:00 2001
From: MartinGC94 <42123497+MartinGC94@users.noreply.github.com>
Date: Tue, 18 Feb 2025 06:44:28 +0100
Subject: [PATCH] Use types from both sides of the pipeline chain for the type
 inference (#25031)

---
 .../engine/parser/TypeInferenceVisitor.cs                 | 2 +-
 test/powershell/engine/Api/TypeInference.Tests.ps1        | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/System.Management.Automation/engine/parser/TypeInferenceVisitor.cs b/src/System.Management.Automation/engine/parser/TypeInferenceVisitor.cs
index 0f3f81adcd..0d160a6fb7 100644
--- a/src/System.Management.Automation/engine/parser/TypeInferenceVisitor.cs
+++ b/src/System.Management.Automation/engine/parser/TypeInferenceVisitor.cs
@@ -2596,7 +2596,7 @@ namespace System.Management.Automation
             var types = new List<PSTypeName>();
             types.AddRange(InferTypes(pipelineChainAst.LhsPipelineChain));
             types.AddRange(InferTypes(pipelineChainAst.RhsPipeline));
-            return GetArrayType(types);
+            return types.Distinct();
         }
 
         private static CommandBaseAst GetPreviousPipelineCommand(CommandAst commandAst)
diff --git a/test/powershell/engine/Api/TypeInference.Tests.ps1 b/test/powershell/engine/Api/TypeInference.Tests.ps1
index 1fe25de530..8a1d9670bb 100644
--- a/test/powershell/engine/Api/TypeInference.Tests.ps1
+++ b/test/powershell/engine/Api/TypeInference.Tests.ps1
@@ -442,6 +442,14 @@ Describe "Type inference Tests" -tags "CI" {
         }
     }
 
+    It 'Infers typeof pipeline chain' {
+        $ast = {New-TimeSpan && New-Guid}.Ast
+        $typeNames = [AstTypeInference]::InferTypeof($ast, [TypeInferenceRuntimePermissions]::AllowSafeEval)
+        $typeNames.Count | Should -Be 2
+        $typeNames[0] | Should -Be 'System.TimeSpan'
+        $typeNames[1] | Should -Be 'System.Guid'
+    }
+
     It "Infers typeof pscustomobject" {
 
         $res = [AstTypeInference]::InferTypeOf( { [pscustomobject] @{