Use right error; only drop unneeded fields from spreads

brianrourkeboll · brianrourkeboll · commit d181c974868f · 2025-09-24T18:03:39.000-04:00
diff --git a/src/Compiler/Checking/Expressions/CheckExpressions.fs b/src/Compiler/Checking/Expressions/CheckExpressions.fs
@@ -8074,13 +8074,17 @@ and TcNewAnonRecdExpr cenv (overallTy: TType) env tpenv (isStruct, unsortedField
             match fieldsAndSpreads with
             | [] ->
                 // If the target type is a known anonymous record type,
-                // keep only those fields that are present in that type.
+                // keep only those fields that are present in that type
+                // or that are explicitly defined in this one.
                 let checkedFields =
                     maybeAnonRecdTargetTy
                     |> ValueOption.map (fun (anonInfo, _) ->
                         let sortedNames = anonInfo.SortedNames
                         checkedFields
-                        |> Map.filter (fun fieldId _ -> Array.BinarySearch (sortedNames, fieldId) >= 0))
+                        |> Map.filter (fun fieldId field ->
+                            match field with
+                            | LeftwardExplicit, _ -> true
+                            | NoLeftwardExplicit, _ -> Array.BinarySearch (sortedNames, fieldId) >= 0))
                     |> ValueOption.defaultValue checkedFields
 
                 // We must emit let-bindings for the source expressions in their original order.
@@ -8122,7 +8126,7 @@ and TcNewAnonRecdExpr cenv (overallTy: TType) env tpenv (isStruct, unsortedField
                         //
                         // Keep both, but error.
                         | Some (LeftwardExplicit, dupes) ->
-                            errorR (Duplicate ("field", fieldId.idText, m))
+                            errorR (Error (FSComp.SR.tcAnonRecdDuplicateFieldId fieldId.idText, m))
                             Some (LeftwardExplicit, (i, fieldId, ty, expr) :: dupes)
 
                         // Rightward explicit field shadowing leftward spread field.
@@ -8334,7 +8338,8 @@ and TcCopyAndUpdateAnonRecdExpr cenv (overallTy: TType) env tpenv (isStruct, (or
             match fieldsAndSpreads with
             | [] ->
                 // If the target type is a known anonymous record type,
-                // keep only those fields that are present in that type.
+                // keep only those fields that are present in that type
+                // or that are explicitly defined in this one.
                 let shouldKeep =
                     match tryDestAnonRecdTy g overallTy with
                     | ValueSome (anonInfo, _) ->
@@ -8345,7 +8350,9 @@ and TcCopyAndUpdateAnonRecdExpr cenv (overallTy: TType) env tpenv (isStruct, (or
                 let fieldsInOriginalOrder =
                     flds
                     |> Map.toList
-                    |> List.collect (fun (fieldId, (_, dupes)) -> if shouldKeep fieldId then dupes else [])
+                    |> List.collect (function
+                        | _, (LeftwardExplicit, dupes) -> dupes
+                        | fieldId, (NoLeftwardExplicit, dupes) -> if shouldKeep fieldId then dupes else [])
                     |> List.sortBy (fun (i, _) -> i)
                     |> List.map (fun (_, field) -> field)
 
@@ -8375,7 +8382,7 @@ and TcCopyAndUpdateAnonRecdExpr cenv (overallTy: TType) env tpenv (isStruct, (or
                         //
                         // Keep both, but error.
                         | Some (LeftwardExplicit, dupes) ->
-                            errorR (Duplicate ("field", fieldId.idText, m))
+                            errorR (Error (FSComp.SR.tcAnonRecdDuplicateFieldId fieldId.idText, m))
                             Some (LeftwardExplicit, (i, field) :: dupes)
 
                         // Rightward explicit field shadowing leftward spread field.
diff --git a/tests/FSharp.Compiler.ComponentTests/EmittedIL/Spreads/Expression_Nominal_SpreadShadowsSpread.fs.il.bsl b/tests/FSharp.Compiler.ComponentTests/EmittedIL/Spreads/Expression_Nominal_SpreadShadowsSpread.fs.il.bsl
@@ -461,6 +461,8 @@
   .custom instance void [runtime]System.Diagnostics.DebuggerBrowsableAttribute::.ctor(valuetype [runtime]System.Diagnostics.DebuggerBrowsableState) = ( 01 00 00 00 00 00 00 00 ) 
   .field static assembly class assembly/R1 spreadSrc@4
   .custom instance void [runtime]System.Diagnostics.DebuggerBrowsableAttribute::.ctor(valuetype [runtime]System.Diagnostics.DebuggerBrowsableState) = ( 01 00 00 00 00 00 00 00 ) 
+  .field static assembly int32 B@4
+  .custom instance void [runtime]System.Diagnostics.DebuggerBrowsableAttribute::.ctor(valuetype [runtime]System.Diagnostics.DebuggerBrowsableState) = ( 01 00 00 00 00 00 00 00 ) 
   .method public specialname static class assembly/R1 get_r1() cil managed
   {
     
@@ -485,6 +487,14 @@
     IL_0005:  ret
   } 
 
+  .method assembly specialname static int32 get_B@4() cil managed
+  {
+    
+    .maxstack  8
+    IL_0000:  ldsfld     int32 assembly::B@4
+    IL_0005:  ret
+  } 
+
   .method private specialname rtspecialname static void  .cctor() cil managed
   {
     
@@ -499,7 +509,7 @@
   .method assembly specialname static void staticInitialization@() cil managed
   {
     
-    .maxstack  8
+    .maxstack  4
     IL_0000:  ldc.i4.1
     IL_0001:  ldc.i4.2
     IL_0002:  newobj     instance void assembly/R1::.ctor(int32,
@@ -508,14 +518,16 @@
     IL_000c:  ldc.i4.s   99
     IL_000e:  newobj     instance void class '<>f__AnonymousType1722350077`1'<int32>::.ctor(!0)
     IL_0013:  stsfld     class assembly/R1 assembly::spreadSrc@4
-    IL_0018:  call       class assembly/R1 assembly::get_spreadSrc@4()
-    IL_001d:  call       instance !0 class '<>f__AnonymousType1722350077`1'<int32>::get_A()
-    IL_0022:  call       class assembly/R1 assembly::get_r1()
-    IL_0027:  ldfld      int32 assembly/R1::B@
-    IL_002c:  newobj     instance void assembly/R1::.ctor(int32,
+    IL_0018:  call       class assembly/R1 assembly::get_r1()
+    IL_001d:  ldfld      int32 assembly/R1::B@
+    IL_0022:  stsfld     int32 assembly::B@4
+    IL_0027:  call       class assembly/R1 assembly::get_spreadSrc@4()
+    IL_002c:  call       instance !0 class '<>f__AnonymousType1722350077`1'<int32>::get_A()
+    IL_0031:  call       int32 assembly::get_B@4()
+    IL_0036:  newobj     instance void assembly/R1::.ctor(int32,
                                                                                         int32)
-    IL_0031:  stsfld     class assembly/R1 assembly::'r1\'@4'
-    IL_0036:  ret
+    IL_003b:  stsfld     class assembly/R1 assembly::'r1\'@4'
+    IL_0040:  ret
   } 
 
   .property class assembly/R1
@@ -536,6 +548,11 @@
     .custom instance void [FSharp.Core]Microsoft.FSharp.Core.CompilationMappingAttribute::.ctor(valuetype [FSharp.Core]Microsoft.FSharp.Core.SourceConstructFlags) = ( 01 00 09 00 00 00 00 00 ) 
     .get class assembly/R1 assembly::get_spreadSrc@4()
   } 
+  .property int32 B@4()
+  {
+    .custom instance void [FSharp.Core]Microsoft.FSharp.Core.CompilationMappingAttribute::.ctor(valuetype [FSharp.Core]Microsoft.FSharp.Core.SourceConstructFlags) = ( 01 00 09 00 00 00 00 00 ) 
+    .get int32 assembly::get_B@4()
+  } 
 } 
 
 .class private abstract auto ansi sealed '<StartupCode$assembly>'.$assembly
diff --git a/tests/FSharp.Compiler.ComponentTests/Language/SpreadTests.fs b/tests/FSharp.Compiler.ComponentTests/Language/SpreadTests.fs
@@ -659,7 +659,7 @@ module NominalAndAnonymousRecords =
                 |> shouldFail
                 |> withDiagnostics [
                     Warning 3883, Line 4, Col 42, Line 4, Col 47, "Spread field 'A: int' shadows an explicitly declared field with the same name."
-                    Error 37, Line 4, Col 49, Line 4, Col 57, "Duplicate definition of field 'A'"
+                    Error 3522, Line 4, Col 49, Line 4, Col 57, "The field 'A' appears multiple times in this record expression."
                     Error 3522, Line 5, Col 31, Line 5, Col 71, "The field 'A' appears multiple times in this record expression."
                 ]
 
@@ -680,7 +680,7 @@ module NominalAndAnonymousRecords =
                 |> shouldFail
                 |> withDiagnostics [
                     Warning 3883, Line 5, Col 49, Line 5, Col 54, "Spread field 'A: int' shadows an explicitly declared field with the same name."
-                    Error 37, Line 5, Col 56, Line 5, Col 64, "Duplicate definition of field 'A'"
+                    Error 3522, Line 5, Col 56, Line 5, Col 64, "The field 'A' appears multiple times in this record expression."
                     Error 3522, Line 6, Col 31, Line 6, Col 78, "The field 'A' appears multiple times in this record expression."
                 ]
 
@@ -1206,7 +1206,7 @@ module NominalAndAnonymousRecords =
                     Error 37, Line 4, Col 46, Line 4, Col 51, "Duplicate definition of field 'A'"
                     Warning 3883, Line 4, Col 53, Line 4, Col 67, "Spread field 'A: int' shadows an explicitly declared field with the same name."
                     Error 37, Line 4, Col 69, Line 4, Col 74, "Duplicate definition of field 'A'"
-                    Error 668, Line 4, Col 69, Line 4, Col 70, "The field 'A' appears multiple times in this record expression or pattern"
+                    Error 668, Line 4, Col 59, Line 4, Col 60, "The field 'A' appears multiple times in this record expression or pattern"
                 ]
 
             /// Extra fields are ignored.
