Parser: recover on missing items in tuple patterns

src/Compiler/FSComp.txt

@@ -1653,3 +1653,5 @@ reprStateMachineInvalidForm,"The state machine has an unexpected form"
 3536,tcUsingInterfaceWithStaticAbstractMethodAsType,"'%s' is normally used as a type constraint in generic code, e.g. \"'T when ISomeInterface<'T>\" or \"let f (x: #ISomeInterface<_>)\". See https://aka.ms/fsharp-iwsams for guidance. You can disable this warning by using '#nowarn \"3536\"' or '--nowarn:3536'."
 3537,tcTraitHasMultipleSupportTypes,"The trait '%s' invoked by this call has multiple support types. This invocation syntax is not permitted for such traits. See https://aka.ms/fsharp-srtp for guidance."
 3545,tcMissingRequiredMembers,"The following required properties have to be initalized:%s"
+3546,parsExpectingPatternInTuple,"Expecting pattern"
+3547,parsExpectedPatternAfterToken,"Expected a pattern after this point"

src/Compiler/SyntaxTree/SyntaxTreeOps.fs

@@ -1031,6 +1031,13 @@ let rec normalizeTupleExpr exprs commas : SynExpr list * range list =
         innerExprs @ rest, innerCommas @ commas
     | _ -> exprs, commas
 
+let rec normalizeTuplePat pats : SynPat list =
+    match pats with
+    | SynPat.Tuple (false, innerPats, _) :: rest ->
+        let innerExprs = normalizeTuplePat (List.rev innerPats)
+        innerExprs @ rest
+    | _ -> pats
+
 /// Remove all members that were captures as SynMemberDefn.GetSetMember
 let rec desugarGetSetMembers (memberDefns: SynMemberDefns) =
     memberDefns

src/Compiler/SyntaxTree/SyntaxTreeOps.fsi

@@ -350,6 +350,8 @@ val mkDynamicArgExpr: expr: SynExpr -> SynExpr
 
 val normalizeTupleExpr: exprs: SynExpr list -> commas: range list -> SynExpr list * range List
 
+val normalizeTuplePat: pats: SynPat list -> SynPat list
+
 val desugarGetSetMembers: memberDefns: SynMemberDefns -> SynMemberDefns
 
 val getTypeFromTuplePath: path: SynTupleTypeSegment list -> SynType list

src/Compiler/pars.fsy

@@ -3126,21 +3126,48 @@ headBindingPattern:
   | headBindingPattern COLON_COLON  headBindingPattern 
       { SynPat.LongIdent (SynLongIdent(mkSynCaseName (rhs parseState 2) opNameCons, [], [ Some (IdentTrivia.OriginalNotation "::") ]), None, None, SynArgPats.Pats [SynPat.Tuple (false, [$1;$3], rhs2 parseState 1 3)], None, lhs parseState) }
 
-  | tuplePatternElements  %prec pat_tuple 
-      { SynPat.Tuple(false, List.rev $1, lhs parseState) }
+  | tuplePatternElements %prec pat_tuple
+      { let pats = normalizeTuplePat $1
+        let m = (rhs parseState 1, pats) ||> unionRangeWithListBy (fun p -> p.Range)
+        SynPat.Tuple(false, List.rev pats, m) }
 
   | conjPatternElements   %prec pat_conj
       { SynPat.Ands(List.rev $1, lhs parseState) }
 
   | constrPattern 
       { $1 }
 
-tuplePatternElements: 
-  | tuplePatternElements COMMA headBindingPattern 
+tuplePatternElements:
+  | tuplePatternElements COMMA headBindingPattern
       { $3 :: $1 }
 
-  | headBindingPattern COMMA headBindingPattern 
-      { $3 :: $1 :: [] }
+  | headBindingPattern COMMA headBindingPattern
+      { [$3; $1] }
+
+  | tuplePatternElements COMMA ends_coming_soon_or_recover
+        { let commaRange = rhs parseState 2
+          reportParseErrorAt commaRange (FSComp.SR.parsExpectingPatternInTuple ())
+          let pat2 = SynPat.Wild(commaRange.EndRange)
+          pat2 :: $1 }
+
+  | headBindingPattern COMMA ends_coming_soon_or_recover
+      { let commaRange = rhs parseState 2
+        reportParseErrorAt commaRange (FSComp.SR.parsExpectingPatternInTuple ())
+        let pat2 = SynPat.Wild(commaRange.EndRange)
+        [pat2; $1] }
+
+  | COMMA headBindingPattern
+      { let commaRange = rhs parseState 1
+        reportParseErrorAt commaRange (FSComp.SR.parsExpectingPatternInTuple ())
+        let pat1 = SynPat.Wild(commaRange.StartRange)
+        [$2; pat1] }
+
+  | COMMA ends_coming_soon_or_recover
+      { let commaRange = rhs parseState 1
+        if not $2 then reportParseErrorAt commaRange (FSComp.SR.parsExpectedPatternAfterToken ())
+        let pat1 = SynPat.Wild(commaRange.StartRange)
+        let pat2 = SynPat.Wild(commaRange.EndRange)
+        [pat2; pat1] }
 
 conjPatternElements: 
   | conjPatternElements AMP headBindingPattern 
@@ -3351,8 +3378,10 @@ parenPattern:
       { let mBar = rhs parseState 2
         SynPat.Or($1, $3, rhs2 parseState 1 3, { BarRange = mBar }) }
 
-  | tupleParenPatternElements 
-      { SynPat.Tuple(false, List.rev $1, lhs parseState) }
+  | tupleParenPatternElements
+      { let pats = normalizeTuplePat $1
+        let m = (rhs parseState 1, pats) ||> unionRangeWithListBy (fun p -> p.Range)
+        SynPat.Tuple(false, List.rev pats, m) }
 
   | conjParenPatternElements
       { SynPat.Ands(List.rev $1, rhs2 parseState 1 3) }
@@ -3371,11 +3400,36 @@ parenPattern:
   | constrPattern { $1 }
 
 tupleParenPatternElements:
-  | tupleParenPatternElements COMMA parenPattern  
+  | tupleParenPatternElements COMMA parenPattern
       { $3 :: $1 }
 
-  | parenPattern COMMA parenPattern  
-      { $3 :: $1 :: [] }
+  | parenPattern COMMA parenPattern
+      { [$3; $1] }
+
+  | tupleParenPatternElements COMMA ends_coming_soon_or_recover
+        { let commaRange = rhs parseState 2
+          reportParseErrorAt commaRange (FSComp.SR.parsExpectingPatternInTuple())
+          let pat2 = SynPat.Wild(commaRange.EndRange)
+          pat2 :: $1 }
+
+  | parenPattern COMMA ends_coming_soon_or_recover
+      { let commaRange = rhs parseState 2
+        reportParseErrorAt commaRange (FSComp.SR.parsExpectingPatternInTuple())
+        let pat2 = SynPat.Wild(commaRange.EndRange)
+        [pat2; $1] }
+
+  | COMMA parenPattern
+      { let commaRange = rhs parseState 1
+        reportParseErrorAt commaRange (FSComp.SR.parsExpectingPatternInTuple())
+        let pat1 = SynPat.Wild(commaRange.StartRange)
+        [$2; pat1] }
+
+  | COMMA ends_coming_soon_or_recover
+      { let commaRange = rhs parseState 1
+        if not $2 then reportParseErrorAt commaRange (FSComp.SR.parsExpectedPatternAfterToken ())
+        let pat1 = SynPat.Wild(commaRange.StartRange)
+        let pat2 = SynPat.Wild(commaRange.EndRange)
+        [pat2; pat1] }
 
 conjParenPatternElements: 
   | conjParenPatternElements AMP parenPattern 

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

@@ -592,6 +592,16 @@
         <target state="translated">Neočekávaný token v definici typu. Za typem {0} se očekává =.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

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

@@ -592,6 +592,16 @@
         <target state="translated">Unerwartetes Token in Typdefinition. Nach Typ "{0}" wurde "=" erwartet.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

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

@@ -592,6 +592,16 @@
         <target state="translated">Token inesperado en la definición de tipo. Se esperaba "=" después del tipo "{0}".</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

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

@@ -592,6 +592,16 @@
         <target state="translated">Jeton inattendu dans la définition de type. Signe '=' attendu après le type '{0}'.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

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

@@ -592,6 +592,16 @@
         <target state="translated">Token imprevisto nella definizione del tipo. Dopo il tipo '{0}' è previsto '='.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

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

@@ -592,6 +592,16 @@
         <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="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

src/Compiler/xlf/FSComp.txt.ko.xlf

@@ -592,6 +592,16 @@
         <target state="translated">형식 정의에 예기치 않은 토큰이 있습니다. '{0}' 형식 뒤에 '='가 필요합니다.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

src/Compiler/xlf/FSComp.txt.pl.xlf

@@ -592,6 +592,16 @@
         <target state="translated">Nieoczekiwany token w definicji typu. Oczekiwano znaku „=” po typie „{0}”.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

src/Compiler/xlf/FSComp.txt.pt-BR.xlf

@@ -592,6 +592,16 @@
         <target state="translated">Token inesperado na definição de tipo. Esperava-se '=' após o tipo '{0}'.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

src/Compiler/xlf/FSComp.txt.ru.xlf

@@ -592,6 +592,16 @@
         <target state="translated">Неожиданный токен в определении типа. После типа "{0}" ожидается "=".</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

src/Compiler/xlf/FSComp.txt.tr.xlf

@@ -592,6 +592,16 @@
         <target state="translated">Tür tanımında beklenmeyen belirteç var. '{0}' türünden sonra '=' bekleniyordu.</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

src/Compiler/xlf/FSComp.txt.zh-Hans.xlf

@@ -592,6 +592,16 @@
         <target state="translated">类型定义中出现意外标记。类型“{0}”后应为 "="。</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

src/Compiler/xlf/FSComp.txt.zh-Hant.xlf

@@ -592,6 +592,16 @@
         <target state="translated">型別定義中出現非預期的權杖。類型 '{0}' 之後應該要有 '='。</target>
         <note />
       </trans-unit>
+      <trans-unit id="parsExpectedPatternAfterToken">
+        <source>Expected a pattern after this point</source>
+        <target state="new">Expected a pattern after this point</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="parsExpectingPatternInTuple">
+        <source>Expecting pattern</source>
+        <target state="new">Expecting pattern</target>
+        <note />
+      </trans-unit>
       <trans-unit id="parsIncompleteTyparExpr1">
         <source>Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</source>
         <target state="new">Incomplete character literal (example: 'Q') or qualified type invocation (example: 'T.Name)</target>

tests/service/Common.fs

@@ -232,6 +232,11 @@ let getSingleParenInnerExpr expr =
     | SynModuleDecl.Expr(SynExpr.Paren(expr, _, _, _), _) -> expr
     | _ -> failwith "Unexpected tree"
 
+let getLetDeclHeadPattern (moduleDecl: SynModuleDecl) =
+    match moduleDecl with
+    | SynModuleDecl.Let(_, [SynBinding(headPat = pat)], _) -> pat
+    | _ -> failwith "Unexpected tree"
+
 let parseSourceCodeAndGetModule (source: string) =
     parseSourceCode ("test.fsx", source) |> getSingleModuleLikeDecl
 
@@ -458,7 +463,7 @@ let coreLibAssemblyName =
     "mscorlib"
 #endif
 
-let getRange (e: SynExpr) = e.Range
+let inline getRange (node: ^T) = (^T: (member Range: range) node)
 
 let assertRange
     (expectedStartLine: int, expectedStartColumn: int)