From 060c90a0248a5392a7784572b08394aca11c48fe Mon Sep 17 00:00:00 2001
From: MartinGC94 <MGC94@outlook.dk>
Date: Sun, 4 Feb 2024 18:33:40 +0100
Subject: [PATCH] Fall back to type inference when hashtable key value cannot
 be retrieved from safe expression

---
 .../engine/parser/TypeInferenceVisitor.cs     | 37 ++++++++++---------
 .../engine/Api/TypeInference.Tests.ps1        | 12 ++++++
 2 files changed, 31 insertions(+), 18 deletions(-)

diff --git a/src/System.Management.Automation/engine/parser/TypeInferenceVisitor.cs b/src/System.Management.Automation/engine/parser/TypeInferenceVisitor.cs
index 1e1ff771ac5..be864a8a814 100644
--- a/src/System.Management.Automation/engine/parser/TypeInferenceVisitor.cs
+++ b/src/System.Management.Automation/engine/parser/TypeInferenceVisitor.cs
@@ -584,6 +584,20 @@ object ICustomAstVisitor.VisitHashtable(HashtableAst hashtableAst)
             if (hashtableAst.KeyValuePairs.Count > 0)
             {
                 var properties = new List<PSMemberNameAndType>();
+                void AddInferredTypes(Ast ast, string keyName)
+                {
+                    bool foundAnyTypes = false;
+                    foreach (PSTypeName item in InferTypes(ast))
+                    {
+                        foundAnyTypes = true;
+                        properties.Add(new PSMemberNameAndType(keyName, item));
+                    }
+
+                    if (!foundAnyTypes)
+                    {
+                        properties.Add(new PSMemberNameAndType(keyName, new PSTypeName("System.Object")));
+                    }
+                }
 
                 foreach (var kv in hashtableAst.KeyValuePairs)
                 {
@@ -615,31 +629,18 @@ object ICustomAstVisitor.VisitHashtable(HashtableAst hashtableAst)
                                 _ = SafeExprEvaluator.TrySafeEval(expression, _context.ExecutionContext, out value);
                             }
 
-                            PSTypeName valueType;
                             if (value is null)
                             {
-                                valueType = new PSTypeName("System.Object");
-                            }
-                            else
-                            {
-                                valueType = new PSTypeName(value.GetType());
+                                AddInferredTypes(expression, name);
+                                continue;
                             }
 
+                            PSTypeName valueType = new(value.GetType());
                             properties.Add(new PSMemberNameAndType(name, valueType, value));
                         }
                         else
                         {
-                            bool foundAnyTypes = false;
-                            foreach (var item in InferTypes(kv.Item2))
-                            {
-                                foundAnyTypes = true;
-                                properties.Add(new PSMemberNameAndType(name, item));
-                            }
-
-                            if (!foundAnyTypes)
-                            {
-                                properties.Add(new PSMemberNameAndType(name, new PSTypeName("System.Object")));
-                            }
+                            AddInferredTypes(kv.Item2, name);
                         }
                     }
                 }
@@ -1639,7 +1640,7 @@ private IEnumerable<PSTypeName> InferTypesFrom(MemberExpressionAst memberExpress
             var memberNameList = new List<string> { memberAsStringConst.Value };
             foreach (var type in exprType)
             {
-                if (type.Type == typeof(PSObject))
+                if (type.Type == typeof(PSObject) && type is not PSSyntheticTypeName)
                 {
                     continue;
                 }
diff --git a/test/powershell/engine/Api/TypeInference.Tests.ps1 b/test/powershell/engine/Api/TypeInference.Tests.ps1
index 69817f6290d..7676ecf3197 100644
--- a/test/powershell/engine/Api/TypeInference.Tests.ps1
+++ b/test/powershell/engine/Api/TypeInference.Tests.ps1
@@ -1379,12 +1379,24 @@ Describe "Type inference Tests" -tags "CI" {
         $res.Name -join ' ' | Should -Be "System.IO.FileInfo System.IO.DirectoryInfo"
     }
 
+    It 'Falls back to type inference for hashtable assignments with pure expression with no value' {
+        $res = [AstTypeInference]::InferTypeOf( {$KeyWithNoValue = Get-ChildItem $HOME; (@{RandomKey = $KeyWithNoValue}).RandomKey }.Ast)
+        $Res.Count | Should -Be 2
+        $res.Name -join ' ' | Should -Be "System.IO.FileInfo System.IO.DirectoryInfo"
+    }
+
     It 'Infers type of index expression on hashtable with synthetic type' {
         $res = [AstTypeInference]::InferTypeOf( { (@{RandomKey = Get-ChildItem $HOME})['RandomKey'] }.Ast)
         $res.Count | Should -Be 2
         $res.Name -join ' ' | Should -Be "System.IO.FileInfo System.IO.DirectoryInfo"
     }
 
+    It 'Infers type of member expression on a custom object' {
+        $res = [AstTypeInference]::InferTypeOf( { ([pscustomobject]@{RandomProp1 = Get-ChildItem $HOME}).RandomProp1 }.Ast)
+        $res.Count | Should -Be 2
+        $res.Name -join ' ' | Should -Be "System.IO.FileInfo System.IO.DirectoryInfo"
+    }
+
     It 'Infers closest variable type' {
         $res = [AstTypeInference]::InferTypeOf( { [string]$TestVar = "";[hashtable]$TestVar = @{};$TestVar }.Ast)
         $res.Name | Select-Object -Last 1 | Should -Be "System.Collections.Hashtable"