Relax Patch(record, updates...) field-type strictness and preserve unioned record shape

src/libraries/Microsoft.PowerFx.Core/Texl/Builtins/Patch.cs

@@ -707,22 +707,7 @@ public override bool CheckTypes(CheckTypesContext context, TexlNode[] args, DTyp
                     continue;
                 }
 
-                // Ensure that if the key in argument1 exists in the current record, their types match.
-                bool isSafeToUnion = true;
-                foreach (var typedName in curType.GetNames(DPath.Root))
-                {
-                    DName name = typedName.Name;
-                    if (recordType.TryGetType(name, out DType nameType) && !nameType.Accepts(typedName.Type, exact: true, useLegacyDateTimeAccepts: false, usePowerFxV1CompatibilityRules: context.Features.PowerFxV1CompatibilityRules))
-                    {
-                        errors.EnsureError(args[i], TexlStrings.ErrTypeError_Arg_Expected_Found, name, nameType.GetKindString(), typedName.Type.GetKindString());
-                        isValid = isSafeToUnion = false;
-                    }
-                }
-
-                if (isSafeToUnion)
-                {
-                    retType = DType.Union(retType, curType, useLegacyDateTimeAccepts: false, context.Features);
-                }
+                retType = DType.Union(retType, curType, useLegacyDateTimeAccepts: false, context.Features);
             }
 
             returnType = retType;

src/tests/Microsoft.PowerFx.Core.Tests.Shared/TexlTests.cs

@@ -4559,18 +4559,51 @@ public void TexlFunctionTypeSemanticsTable_PageableInputs(string script, string
         [InlineData("Abs(Type(Number))", "n")]
         [InlineData("If(Type(Boolean), 1, 2)", "n")]
         [InlineData("Concatenate(Type(Text))", "s")]
-        public void TestTypeLiteralsNegative(string script, string expectedSchema)
-        {
-            TestBindingErrors(
-                script,
-                TestUtils.DT(expectedSchema),
-                features: Features.PowerFxV1);
-        }
-
-        [Theory]
-
-        // Exact type match: all arguments directly match the data source schema *[Name:s, Value:n]
-        [InlineData("Patch(MyDataSource, MyRecord, { Name: \"Hello\", Value: 1 })", true)]
+        public void TestTypeLiteralsNegative(string script, string expectedSchema)
+        {
+            TestBindingErrors(
+                script,
+                TestUtils.DT(expectedSchema),
+                features: Features.PowerFxV1);
+        }
+
+        [Theory]
+        [InlineData("Patch({a:1}, {b:2})", "![a:n, b:n]")]
+        [InlineData("Patch({a:1}, {b:\"test\"})", "![a:n, b:s]")]
+        [InlineData("Patch({a:1, b:2}, {b:\"3\", c:4})", "![a:n, b:s, c:n]")]
+        [InlineData("Patch({x:true}, {y:Date(2020,1,1)})", "![x:b, y:D]")]
+        public void TestPatchRecordFunction(string script, string expectedType)
+        {
+            Assert.True(DType.TryParse(expectedType, out var type), script);
+            Assert.True(type.IsValid, script);
+
+            TestSimpleBindingSuccess(script, type);
+        }
+
+        [Theory]
+        [InlineData("Patch(rec1, {b:2})", "![a:n, b:n]", "![a:n]", "rec1")]
+        [InlineData("Patch(rec2, {c:\"new\"})", "![a:n, b:s, c:s]", "![a:n, b:s]", "rec2")]
+        [InlineData("Patch(rec3, {b:3, c:4})", "![a:n, b:n, c:n]", "![a:n, b:n]", "rec3")]
+        [InlineData("Patch(rec4, {y:Date(2020,1,1)})", "![x:b, y:D]", "![x:b]", "rec4")]
+        [InlineData("Patch(rec5, {x:123})", "![x:$]", "![x:$]", "rec5")]
+        public void TestPatchRecordFunctionWithVariable(string script, string expectedType, string variableType, string variableName)
+        {
+            Assert.True(DType.TryParse(expectedType, out var type), script);
+            Assert.True(type.IsValid, script);
+
+            Assert.True(DType.TryParse(variableType, out var varType), script);
+            Assert.True(varType.IsValid, script);
+
+            var symbol = new SymbolTable();
+            symbol.AddVariable(variableName, FormulaType.Build(varType));
+
+            TestSimpleBindingSuccess(script, type, symbol);
+        }
+
+        [Theory]
+
+        // Exact type match: all arguments directly match the data source schema *[Name:s, Value:n]
+        [InlineData("Patch(MyDataSource, MyRecord, { Name: \"Hello\", Value: 1 })", true)]
 
         // Exact type match: all arguments directly match the data source schema using display names
         [InlineData("Patch(MyDataSource, MyRecord, { DisplayNameForName: \"Hello\", DisplayNameForValue: 1 })", true)]