Wrong type is reported in type mismatch error (#13347)

Co-authored-by: Petr Pokorny <petrpokorny@microsoft.com>
Co-authored-by: Tomas Grosup <tomasgrosup@microsoft.com>
Co-authored-by: Don Syme <dsyme@users.noreply.github.com>

src/Compiler/Checking/CheckExpressions.fs

@@ -590,8 +590,8 @@ let UnifyTupleTypeAndInferCharacteristics contextInfo (cenv: cenv) denv m knownT
         if isAnyTupleTy g knownTy then
             let tupInfo, ptys = destAnyTupleTy g knownTy
             let tupInfo = (if isExplicitStruct then tupInfoStruct else tupInfo)
-            let ptys = 
-                if List.length ps = List.length ptys then ptys 
+            let ptys =
+                if List.length ps = List.length ptys then ptys
                 else NewInferenceTypes g ps
             tupInfo, ptys
         else
@@ -5288,11 +5288,16 @@ and TcExprThenDynamic (cenv: cenv) overallTy env tpenv isArg e1 mQmark e2 delaye
 
    TcExprThen cenv overallTy env tpenv isArg appExpr delayed
 
-and TcExprsWithFlexes (cenv: cenv) env m tpenv flexes argTys args =
-    if List.length args <> List.length argTys then error(Error(FSComp.SR.tcExpressionCountMisMatch((List.length argTys), (List.length args)), m))
+and TcExprsWithFlexes (cenv: cenv) env m tpenv flexes (argTys: TType list) (args: SynExpr list) =
+    if args.Length <> argTys.Length then error(Error(FSComp.SR.tcExpressionCountMisMatch((argTys.Length), (args.Length)), m))
     (tpenv, List.zip3 flexes argTys args) ||> List.mapFold (fun tpenv (flex, ty, e) ->
          TcExprFlex cenv flex false ty env tpenv e)
 
+and TcExprsNoFlexes (cenv: cenv) env m tpenv (argTys: TType list) (args: SynExpr list) =
+    if args.Length <> argTys.Length then error(Error(FSComp.SR.tcExpressionCountMisMatch((argTys.Length), (args.Length)), m))
+    (tpenv, List.zip argTys args) ||> List.mapFold (fun tpenv (ty, e) ->
+         TcExprFlex2 cenv ty env false tpenv e)
+
 and CheckSuperInit (cenv: cenv) objTy m =
     let g = cenv.g
 
@@ -5348,7 +5353,7 @@ and TcPropagatingExprLeafThenConvert (cenv: cenv) overallTy actualTy (env: TcEnv
         UnifyTypes cenv env m overallTy.Commit actualTy
         f ()
 
-/// Process a leaf construct, for cases where we propogate the overall type eagerly in
+/// Process a leaf construct, for cases where we propagate the overall type eagerly in
 /// some cases. Then apply additional type-directed conversions.
 ///
 /// However in some cases favour propagating characteristics of the overall type.
@@ -5360,7 +5365,7 @@ and TcPropagatingExprLeafThenConvert (cenv: cenv) overallTy actualTy (env: TcEnv
 ///  - tuple       (except if overallTy is a tuple type or a variable type that can become one)
 ///  - anon record (except if overallTy is an anon record type or a variable type that can become one)
 ///  - record      (except if overallTy is requiresCtor || haveCtor or a record type or a variable type that can become one))
-and TcPossiblyPropogatingExprLeafThenConvert isPropagating (cenv: cenv) (overallTy: OverallTy) (env: TcEnv) m processExpr =
+and TcPossiblyPropagatingExprLeafThenConvert isPropagating (cenv: cenv) (overallTy: OverallTy) (env: TcEnv) m processExpr =
 
     let g = cenv.g
 
@@ -5538,7 +5543,7 @@ and TcExprUndelayed (cenv: cenv) (overallTy: OverallTy) env tpenv (synExpr: SynE
 
     | SynExpr.AnonRecd (isStruct, withExprOpt, unsortedFieldExprs, mWholeExpr) ->
         TcNonControlFlowExpr env <| fun env ->
-        TcPossiblyPropogatingExprLeafThenConvert (fun ty -> isAnonRecdTy g ty || isTyparTy g ty) cenv overallTy env mWholeExpr (fun overallTy ->
+        TcPossiblyPropagatingExprLeafThenConvert (fun ty -> isAnonRecdTy g ty || isTyparTy g ty) cenv overallTy env mWholeExpr (fun overallTy ->
             TcAnonRecdExpr cenv overallTy env tpenv (isStruct, withExprOpt, unsortedFieldExprs, mWholeExpr)
         )
 
@@ -5799,13 +5804,27 @@ and TcExprLazy (cenv: cenv) overallTy env tpenv (synInnerExpr, m) =
     let expr = mkLazyDelayed g m innerTy (mkUnitDelayLambda g m innerExpr)
     expr, tpenv
 
+and CheckTupleIsCorrectLength g (env: TcEnv) m tupleTy (args: 'a list) tcArgs =
+    if isAnyTupleTy g tupleTy then
+        let tupInfo, ptys = destAnyTupleTy g tupleTy
+
+        if args.Length <> ptys.Length then
+            let argTys = NewInferenceTypes g args
+            suppressErrorReporting (fun () -> tcArgs argTys)
+            let expectedTy = TType_tuple (tupInfo, argTys)
+
+            // We let error recovery handle this exception
+            error (ErrorFromAddingTypeEquation(g, env.DisplayEnv, tupleTy, expectedTy,
+                   (ConstraintSolverTupleDiffLengths(env.DisplayEnv, ptys, argTys, m, m)), m))
+
 and TcExprTuple (cenv: cenv) overallTy env tpenv (isExplicitStruct, args, m) =
     let g = cenv.g
-    TcPossiblyPropogatingExprLeafThenConvert (fun ty -> isAnyTupleTy g ty || isTyparTy g ty) cenv overallTy env m (fun overallTy ->
-        let tupInfo, argTys = UnifyTupleTypeAndInferCharacteristics env.eContextInfo cenv env.DisplayEnv m overallTy isExplicitStruct args
+    TcPossiblyPropagatingExprLeafThenConvert (fun ty -> isAnyTupleTy g ty || isTyparTy g ty) cenv overallTy env m (fun overallTy ->
 
-        let flexes = argTys |> List.map (fun _ -> false)
-        let argsR, tpenv = TcExprsWithFlexes cenv env m tpenv flexes argTys args
+        CheckTupleIsCorrectLength g env m overallTy args (fun argTys -> TcExprsNoFlexes cenv env m tpenv argTys args |> ignore)
+
+        let tupInfo, argTys = UnifyTupleTypeAndInferCharacteristics env.eContextInfo cenv env.DisplayEnv m overallTy isExplicitStruct args
+        let argsR, tpenv = TcExprsNoFlexes cenv env m tpenv argTys args
         let expr = mkAnyTupled g m tupInfo argsR argTys
         expr, tpenv
     )
@@ -5882,7 +5901,7 @@ and TcExprRecord (cenv: cenv) overallTy env tpenv (inherits, withExprOpt, synRec
     CallExprHasTypeSink cenv.tcSink (mWholeExpr, env.NameEnv, overallTy.Commit, env.AccessRights)
     let requiresCtor = (GetCtorShapeCounter env = 1) // Get special expression forms for constructors
     let haveCtor = Option.isSome inherits
-    TcPossiblyPropogatingExprLeafThenConvert (fun ty -> requiresCtor || haveCtor || isRecdTy g ty || isTyparTy g ty) cenv overallTy env mWholeExpr (fun overallTy ->
+    TcPossiblyPropagatingExprLeafThenConvert (fun ty -> requiresCtor || haveCtor || isRecdTy g ty || isTyparTy g ty) cenv overallTy env mWholeExpr (fun overallTy ->
         TcRecdExpr cenv overallTy env tpenv (inherits, withExprOpt, synRecdFields, mWholeExpr)
     )
 
@@ -6085,8 +6104,7 @@ and TcExprILAssembly (cenv: cenv) overallTy env tpenv (ilInstrs, synTyArgs, synA
     let argTys = NewInferenceTypes g synArgs
     let tyargs, tpenv = TcTypes cenv NewTyparsOK CheckCxs ItemOccurence.UseInType WarnOnIWSAM.Yes env tpenv synTyArgs
     // No subsumption at uses of IL assembly code
-    let flexes = argTys |> List.map (fun _ -> false)
-    let args, tpenv = TcExprsWithFlexes cenv env m tpenv flexes argTys synArgs
+    let args, tpenv = TcExprsNoFlexes cenv env m tpenv argTys synArgs
     let retTys, tpenv = TcTypes cenv NewTyparsOK CheckCxs ItemOccurence.UseInType WarnOnIWSAM.Yes env tpenv synRetTys
     let returnTy =
         match retTys with
@@ -7151,8 +7169,7 @@ and TcInterpolatedStringExpr cenv (overallTy: OverallTy) env m tpenv (parts: Syn
                 mkCallNewFormat g m printerTy printerArgTy printerResidueTy printerResultTy printerTupleTy str, tpenv
         else
             // Type check the expressions filling the holes
-            let flexes = argTys |> List.map (fun _ -> false)
-            let fillExprs, tpenv = TcExprsWithFlexes cenv env m tpenv flexes argTys synFillExprs
+            let fillExprs, tpenv = TcExprsNoFlexes cenv env m tpenv argTys synFillExprs
 
             let fillExprsBoxed = (argTys, fillExprs) ||> List.map2 (mkCallBox g m)
 
@@ -7178,8 +7195,7 @@ and TcInterpolatedStringExpr cenv (overallTy: OverallTy) env m tpenv (parts: Syn
     | Choice2Of2 createFormattableStringMethod ->
 
         // Type check the expressions filling the holes
-        let flexes = argTys |> List.map (fun _ -> false)
-        let fillExprs, tpenv = TcExprsWithFlexes cenv env m tpenv flexes argTys synFillExprs
+        let fillExprs, tpenv = TcExprsNoFlexes cenv env m tpenv argTys synFillExprs
 
         let fillExprsBoxed = (argTys, fillExprs) ||> List.map2 (mkCallBox g m)
 

src/Compiler/Checking/CheckExpressions.fsi

@@ -623,6 +623,12 @@ val TcExpr:
     synExpr: SynExpr ->
         Expr * UnscopedTyparEnv
 
+/// Check that 'args' have the correct number of elements for a tuple expression.
+/// If not, use 'tcArgs' to type check the given elements to show
+/// their correct types (if known) in the error message and raise the error
+val CheckTupleIsCorrectLength:
+    g: TcGlobals -> env: TcEnv -> m: range -> tupleTy: TType -> args: 'a list -> tcArgs: (TType list -> unit) -> unit
+
 /// Converts 'a..b' to a call to the '(..)' operator in FSharp.Core
 /// Converts 'a..b..c' to a call to the '(.. ..)' operator in FSharp.Core
 val RewriteRangeExpr: synExpr: SynExpr -> SynExpr option

src/Compiler/Checking/CheckPatterns.fs

@@ -423,6 +423,8 @@ and TcPatAnds warnOnUpper cenv env vFlags patEnv ty pats m =
 and TcPatTuple warnOnUpper cenv env vFlags patEnv ty isExplicitStruct args m =
     let g = cenv.g
     try
+        CheckTupleIsCorrectLength g env m ty args (fun argTys -> TcPatterns warnOnUpper cenv env vFlags patEnv argTys args |> ignore)
+
         let tupInfo, argTys = UnifyTupleTypeAndInferCharacteristics env.eContextInfo cenv env.DisplayEnv m ty isExplicitStruct args
         let argsR, acc = TcPatterns warnOnUpper cenv env vFlags patEnv argTys args
         let phase2 values = TPat_tuple(tupInfo, List.map (fun f -> f values) argsR, argTys, m)

src/Compiler/Checking/ConstraintSolver.fs

@@ -1225,9 +1225,9 @@ and SolveTypeEqualsTypeEqns csenv ndeep m2 trace cxsln origl1 origl2 =
        let rec loop l1 l2 = 
            match l1, l2 with 
            | [], [] -> CompleteD 
-           | h1 :: t1, h2 :: t2 -> 
+           | h1 :: t1, h2 :: t2 when t1.Length = t2.Length -> 
                SolveTypeEqualsTypeKeepAbbrevsWithCxsln csenv ndeep m2 trace cxsln h1 h2 ++ (fun () -> loop t1 t2) 
-           | _ -> 
+           | _ ->
                ErrorD(ConstraintSolverTupleDiffLengths(csenv.DisplayEnv, origl1, origl2, csenv.m, m2)) 
        loop origl1 origl2
 

src/Compiler/Driver/CompilerDiagnostics.fs

@@ -440,6 +440,7 @@ module OldStyleMessages =
     let ConstraintSolverTypesNotInSubsumptionRelationE () = Message("ConstraintSolverTypesNotInSubsumptionRelation", "%s%s%s")
     let ErrorFromAddingTypeEquation1E () = Message("ErrorFromAddingTypeEquation1", "%s%s%s")
     let ErrorFromAddingTypeEquation2E () = Message("ErrorFromAddingTypeEquation2", "%s%s%s")
+    let ErrorFromAddingTypeEquationTuplesE () = Message("ErrorFromAddingTypeEquationTuples", "%d%s%d%s%s")
     let ErrorFromApplyingDefault1E () = Message("ErrorFromApplyingDefault1", "%s")
     let ErrorFromApplyingDefault2E () = Message("ErrorFromApplyingDefault2", "")
     let ErrorsFromAddingSubsumptionConstraintE () = Message("ErrorsFromAddingSubsumptionConstraint", "%s%s%s")
@@ -737,6 +738,12 @@ type Exception with
 
         | ErrorFromAddingTypeEquation(error = ConstraintSolverError _ as e) -> e.Output(os, suggestNames)
 
+        | ErrorFromAddingTypeEquation (_g, denv, ty1, ty2, ConstraintSolverTupleDiffLengths (_, tl1, tl2, _, _), _) ->
+            let ty1, ty2, tpcs = NicePrint.minimalStringsOfTwoTypes denv ty1 ty2
+
+            if ty1 <> ty2 + tpcs then
+                os.AppendString(ErrorFromAddingTypeEquationTuplesE().Format tl1.Length ty1 tl2.Length ty2 tpcs)
+
         | ErrorFromAddingTypeEquation (g, denv, ty1, ty2, e, _) ->
             if not (typeEquiv g ty1 ty2) then
                 let ty1, ty2, tpcs = NicePrint.minimalStringsOfTwoTypes denv ty1 ty2

src/Compiler/FSStrings.resx

@@ -573,7 +573,7 @@
   <data name="Parser.TOKEN.AND" xml:space="preserve">
     <value>keyword 'and'</value>
   </data>
-  !<data name="Parser.TOKEN.AND.BANG" xml:space="preserve">
+  <data name="Parser.TOKEN.AND.BANG" xml:space="preserve">
     <value>keyword 'and!'</value>
   </data>
   <data name="Parser.TOKEN.AS" xml:space="preserve">
@@ -907,7 +907,7 @@
     <value>This expression is a function value, i.e. is missing arguments. Its type is {0}.</value>
   </data>
   <data name="UnitTypeExpected" xml:space="preserve">
-    <value>The result of this expression has type '{0}' and is implicitly ignored. Consider using 'ignore' to discard this value explicitly, e.g. 'expr |> ignore', or 'let' to bind the result to a name, e.g. 'let result = expr'.</value>
+    <value>The result of this expression has type '{0}' and is implicitly ignored. Consider using 'ignore' to discard this value explicitly, e.g. 'expr |&gt; ignore', or 'let' to bind the result to a name, e.g. 'let result = expr'.</value>
   </data>
   <data name="UnitTypeExpectedWithEquality" xml:space="preserve">
     <value>The result of this equality expression has type '{0}' and is implicitly discarded. Consider using 'let' to bind the result to a name, e.g. 'let result = expression'.</value>
@@ -1110,4 +1110,7 @@
   <data name="NotUpperCaseConstructorWithoutRQA" xml:space="preserve">
     <value>Lowercase discriminated union cases are only allowed when using RequireQualifiedAccess attribute</value>
   </data>
+  <data name="ErrorFromAddingTypeEquationTuples" xml:space="preserve">
+    <value>Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</value>
+  </data>
 </root>

src/Compiler/Facilities/DiagnosticsLogger.fs

@@ -614,7 +614,7 @@ let conditionallySuppressErrorReporting cond f =
 //------------------------------------------------------------------------
 // Errors as data: Sometimes we have to reify errors as data, e.g. if backtracking
 
-/// The result type of a computational modality to colelct warnings and possibly fail
+/// The result type of a computational modality to collect warnings and possibly fail
 [<NoEquality; NoComparison>]
 type OperationResult<'T> =
     | OkResult of warnings: exn list * result: 'T

src/Compiler/xlf/FSStrings.cs.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="cs" original="../FSStrings.resx">
     <body>
+      <trans-unit id="ErrorFromAddingTypeEquationTuples">
+        <source>Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</source>
+        <target state="new">Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</target>
+        <note />
+      </trans-unit>
       <trans-unit id="HashLoadedSourceHasIssues0">
         <source>One or more informational messages in loaded file.\n</source>
         <target state="translated">Nejméně jedna informační zpráva v načteném souboru\n</target>

src/Compiler/xlf/FSStrings.de.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="de" original="../FSStrings.resx">
     <body>
+      <trans-unit id="ErrorFromAddingTypeEquationTuples">
+        <source>Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</source>
+        <target state="new">Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</target>
+        <note />
+      </trans-unit>
       <trans-unit id="HashLoadedSourceHasIssues0">
         <source>One or more informational messages in loaded file.\n</source>
         <target state="translated">Mindestens eine Informationsmeldung in der geladenen Datei.\n</target>

src/Compiler/xlf/FSStrings.es.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="es" original="../FSStrings.resx">
     <body>
+      <trans-unit id="ErrorFromAddingTypeEquationTuples">
+        <source>Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</source>
+        <target state="new">Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</target>
+        <note />
+      </trans-unit>
       <trans-unit id="HashLoadedSourceHasIssues0">
         <source>One or more informational messages in loaded file.\n</source>
         <target state="translated">Uno o más mensajes informativos en el archivo cargado.\n</target>

src/Compiler/xlf/FSStrings.fr.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="fr" original="../FSStrings.resx">
     <body>
+      <trans-unit id="ErrorFromAddingTypeEquationTuples">
+        <source>Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</source>
+        <target state="new">Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</target>
+        <note />
+      </trans-unit>
       <trans-unit id="HashLoadedSourceHasIssues0">
         <source>One or more informational messages in loaded file.\n</source>
         <target state="translated">Un ou plusieurs messages d’information dans le fichier chargé.\n</target>

src/Compiler/xlf/FSStrings.it.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="it" original="../FSStrings.resx">
     <body>
+      <trans-unit id="ErrorFromAddingTypeEquationTuples">
+        <source>Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</source>
+        <target state="new">Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</target>
+        <note />
+      </trans-unit>
       <trans-unit id="HashLoadedSourceHasIssues0">
         <source>One or more informational messages in loaded file.\n</source>
         <target state="translated">Uno o più messaggi informativi nel file caricato.\n</target>

src/Compiler/xlf/FSStrings.ja.xlf

@@ -2,6 +2,11 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="ja" original="../FSStrings.resx">
     <body>
+      <trans-unit id="ErrorFromAddingTypeEquationTuples">
+        <source>Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</source>
+        <target state="new">Type mismatch. Expecting a tuple of length {0} of type\n    {1}    \nbut given a tuple of length {2} of type\n    {3}    {4}\n</target>
+        <note />
+      </trans-unit>
       <trans-unit id="HashLoadedSourceHasIssues0">
         <source>One or more informational messages in loaded file.\n</source>
         <target state="translated">読み込まれたファイル内の 1 つ以上の情報メッセージ。\n</target>