Parser: recover on missing items in tuple expression (#13352)

* Parser: recover on missing first item in tuple expression

* Fix longer tuples, add test

* Add another test

* Fix perfect formatting

* add an extra line break in a line that has less than 120 chars
* add an extra space after an capitalized pattern

* Add another test

* Another test

* Recover on missing last item

Author: auduchinok

src/Compiler/FSComp.txt

@@ -1644,4 +1644,5 @@ reprStateMachineInvalidForm,"The state machine has an unexpected form"
 3520,invalidXmlDocPosition,"XML comment is not placed on a valid language element."
 3521,tcInvalidMemberDeclNameMissingOrHasParen,"Invalid member declaration. The name of the member is missing or has parentheses."
 3522,tcAnonRecdDuplicateFieldId,"The field '%s' appears multiple times in this record expression."
-3523,tcAnonRecdTypeDuplicateFieldId,"The field '%s' appears multiple times in this anonymous record type."
+3523,tcAnonRecdTypeDuplicateFieldId,"The field '%s' appears multiple times in this anonymous record type."
+3524,parsExpectingExpressionInTuple,"Expecting expression"

src/Compiler/SyntaxTree/SyntaxTreeOps.fs

@@ -985,3 +985,12 @@ let mkDynamicArgExpr expr =
         SynExpr.Const(con, con.Range ident.idRange)
     | SynExpr.Paren (expr = e) -> e
     | e -> e
+
+let rec normalizeTupleExpr exprs commas : SynExpr list * range list =
+    match exprs with
+    | SynExpr.Tuple (false, innerExprs, innerCommas, _) :: rest ->
+        let innerExprs, innerCommas =
+            normalizeTupleExpr (List.rev innerExprs) (List.rev innerCommas)
+
+        innerExprs @ rest, innerCommas @ commas
+    | _ -> exprs, commas

src/Compiler/SyntaxTree/SyntaxTreeOps.fsi

@@ -340,3 +340,5 @@ val (|SynPipeRight3|_|): SynExpr -> (SynExpr * SynExpr * SynExpr * SynExpr) opti
 val prependIdentInLongIdentWithTrivia: ident: SynIdent -> dotm: range -> lid: SynLongIdent -> SynLongIdent
 
 val mkDynamicArgExpr: expr: SynExpr -> SynExpr
+
+val normalizeTupleExpr: exprs: SynExpr list -> commas: range list -> SynExpr list * range List

src/Compiler/pars.fsy

@@ -3831,6 +3831,13 @@ declExpr:
 
   | tupleExpr  %prec expr_tuple
      { let exprs, commas = $1
+       let exprs, commas =
+           // Nested non-struct tuple is only possible during error recovery,
+           // in other situations there are intermediate nodes.
+           match exprs with
+           | SynExpr.Tuple(false, _, _, _) :: _ -> normalizeTupleExpr exprs commas
+           | _ -> exprs, commas
+
        SynExpr.Tuple (false, List.rev exprs, List.rev commas, (commas.Head, exprs) ||> unionRangeWithListBy (fun e -> e.Range) ) }
 
   | declExpr JOIN_IN declExpr
@@ -4187,6 +4194,17 @@ tupleExpr:
   | declExpr COMMA declExpr  
       { [$3 ; $1], [rhs parseState 2] }
 
+  | COMMA declExpr
+      { let commaRange = rhs parseState 1
+        reportParseErrorAt commaRange (FSComp.SR.parsExpectingExpressionInTuple())
+        [$2; arbExpr ("tupleExpr3", commaRange.StartRange)], [commaRange] }
+
+  | COMMA ends_coming_soon_or_recover
+      { if not $2 then reportParseErrorAt (rhs parseState 2) (FSComp.SR.parsExpectedExpressionAfterToken())
+        let commaRange = rhs parseState 1
+        let zeroWidthAtNextToken = (rhs parseState 2).StartRange
+        [(arbExpr("tupleExpr4", zeroWidthAtNextToken)); arbExpr ("tupleExpr5", commaRange.StartRange)], [commaRange] }
+
 minusExpr: 
   | MINUS minusExpr   %prec expr_prefix_plus_minus
       { mkSynPrefix (rhs parseState 1) (unionRanges (rhs parseState 1) $2.Range) "~-" $2 }

src/Compiler/xlf/FSComp.txt.cs.xlf

@@ -517,6 +517,11 @@
         <target state="translated">Neočekávaný token v definici typu. Za typem {0} se očekává =.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectingExpressionInTuple">
+        <source>Expecting expression</source>
+        <target state="new">Expecting expression</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsNewExprMemberAccess">
         <source>This member access is ambiguous. Please use parentheses around the object creation, e.g. '(new SomeType(args)).MemberName'</source>
         <target state="translated">Tento přístup člena je nejednoznačný. Při vytváření objektu použijte závorky, např. (new SomeType(args)).MemberName'</target>

src/Compiler/xlf/FSComp.txt.de.xlf

@@ -517,6 +517,11 @@
         <target state="translated">Unerwartetes Token in Typdefinition. Nach Typ "{0}" wurde "=" erwartet.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectingExpressionInTuple">
+        <source>Expecting expression</source>
+        <target state="new">Expecting expression</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsNewExprMemberAccess">
         <source>This member access is ambiguous. Please use parentheses around the object creation, e.g. '(new SomeType(args)).MemberName'</source>
         <target state="translated">Dieser Memberzugriff ist mehrdeutig. Setzen Sie Klammern um die Objekterstellung, z. B. "(new SomeType(args)). MemberName“</target>

src/Compiler/xlf/FSComp.txt.es.xlf

@@ -517,6 +517,11 @@
         <target state="translated">Token inesperado en la definición de tipo. Se esperaba "=" después del tipo "{0}".</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectingExpressionInTuple">
+        <source>Expecting expression</source>
+        <target state="new">Expecting expression</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsNewExprMemberAccess">
         <source>This member access is ambiguous. Please use parentheses around the object creation, e.g. '(new SomeType(args)).MemberName'</source>
         <target state="translated">Este acceso de miembro es ambiguo. Use paréntesis alrededor de la creación del objeto, por ejemplo, '(nuevo AlgúnTipo(args)).NombreMiembro'</target>

src/Compiler/xlf/FSComp.txt.fr.xlf

@@ -517,6 +517,11 @@
         <target state="translated">Jeton inattendu dans la définition de type. Signe '=' attendu après le type '{0}'.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectingExpressionInTuple">
+        <source>Expecting expression</source>
+        <target state="new">Expecting expression</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsNewExprMemberAccess">
         <source>This member access is ambiguous. Please use parentheses around the object creation, e.g. '(new SomeType(args)).MemberName'</source>
         <target state="translated">L’accès à ce membre est ambigu. Utilisez des parenthèses autour de la création de l’objet, par exemple' (New SomeType (args)). MemberName</target>

src/Compiler/xlf/FSComp.txt.it.xlf

@@ -517,6 +517,11 @@
         <target state="translated">Token imprevisto nella definizione del tipo. Dopo il tipo '{0}' è previsto '='.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectingExpressionInTuple">
+        <source>Expecting expression</source>
+        <target state="new">Expecting expression</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsNewExprMemberAccess">
         <source>This member access is ambiguous. Please use parentheses around the object creation, e.g. '(new SomeType(args)).MemberName'</source>
         <target state="translated">L'accesso ai membri è ambiguo. Utilizzare le parentesi intorno alla creazione oggetto, ad esempio “(New SomeType (args)). MemberName”</target>

src/Compiler/xlf/FSComp.txt.ja.xlf

@@ -517,6 +517,11 @@
         <target state="translated">型定義に予期しないトークンがあります。型 '{0}' の後には '=' が必要です。</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectingExpressionInTuple">
+        <source>Expecting expression</source>
+        <target state="new">Expecting expression</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsNewExprMemberAccess">
         <source>This member access is ambiguous. Please use parentheses around the object creation, e.g. '(new SomeType(args)).MemberName'</source>
         <target state="translated">このメンバーへのアクセスはあいまいです。オブジェクト作成の前後にはかっこを使用してください。例: '(new SomeType(args)).MemberName'</target>