pars.fsy: capture empty interpolated string fills and report error (d…

…otnet#9849) * pars.fsy: capture empty interpolated string fills and report error reduce empty interp fill error range, update tests update error msg 3382 * StringInterp: update test error code
xamarin · Feb 22, 2021 · 9129353 · 9129353
1 parent 43d2886
commit 9129353
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Showing 3 changed files with 31 additions and 7 deletions.
diff --git a/src/fsharp/FSComp.txt b/src/fsharp/FSComp.txt
@@ -1534,5 +1534,6 @@ forFormatInvalidForInterpolated4,"Interpolated strings used as type IFormattable
 3379,parsEofInInterpolatedString,"Incomplete interpolated string begun at or before here"
 3380,parsEofInInterpolatedVerbatimString,"Incomplete interpolated verbatim string begun at or before here"
 3381,parsEofInInterpolatedTripleQuoteString,"Incomplete interpolated triple-quote string begun at or before here"
-3382,lexRBraceInInterpolatedString,"A '}}' character must be escaped (by doubling) in an interpolated string."
+3382,parsEmptyFillInInterpolatedString,"Invalid interpolated string. This interpolated string expression fill is empty, an expression was expected."
+3383,lexRBraceInInterpolatedString,"A '}}' character must be escaped (by doubling) in an interpolated string."
 #3501   "This construct is not supported by your version of the F# compiler" CompilerMessage(ExperimentalAttributeMessages.NotSupportedYet, 3501, IsError=true)
diff --git a/src/fsharp/pars.fsy b/src/fsharp/pars.fsy
@@ -5507,6 +5507,13 @@ interpolatedStringParts:
   | INTERP_STRING_PART interpolatedStringFill interpolatedStringParts
      { SynInterpolatedStringPart.String (fst $1, rhs parseState 1) :: SynInterpolatedStringPart.FillExpr $2 :: $3 }
 
+  | INTERP_STRING_PART interpolatedStringParts
+     { 
+       let rbrace = parseState.InputEndPosition 1
+       let lbrace = parseState.InputStartPosition 2
+       reportParseErrorAt (mkSynRange rbrace lbrace) (FSComp.SR.parsEmptyFillInInterpolatedString())
+       SynInterpolatedStringPart.String (fst $1, rhs parseState 1) :: $2 }
+
 /* INTERP_STRING_BEGIN_END */
 /* INTERP_STRING_BEGIN_PART int32 INTERP_STRING_END */
 /* INTERP_STRING_BEGIN_PART int32 INTERP_STRING_PART int32 INTERP_STRING_END */
@@ -5516,6 +5523,13 @@ interpolatedString:
 
   | INTERP_STRING_BEGIN_END
     { [ SynInterpolatedStringPart.String (fst $1, rhs parseState 1) ] }
+
+  | INTERP_STRING_BEGIN_PART interpolatedStringParts
+    { 
+      let rbrace = parseState.InputEndPosition 1
+      let lbrace = parseState.InputStartPosition 2
+      reportParseErrorAt (mkSynRange rbrace lbrace) (FSComp.SR.parsEmptyFillInInterpolatedString())
+      SynInterpolatedStringPart.String (fst $1, rhs parseState 1) :: $2 }
 
 opt_HIGH_PRECEDENCE_APP:
   | HIGH_PRECEDENCE_BRACK_APP { }

diff --git a/tests/fsharp/Compiler/Language/StringInterpolation.fs b/tests/fsharp/Compiler/Language/StringInterpolation.fs
@@ -683,8 +683,17 @@ let xd = $"%A{}" // empty expression
 """
         CompilerAssert.TypeCheckWithErrorsAndOptions  [| "--langversion:preview" |]
             code
-            [|(FSharpErrorSeverity.Error, 10, (2, 15, 2, 17),
-               "Unexpected interpolated string (final part) in binding")
+            [|(FSharpErrorSeverity.Error, 3382, (2, 15, 2, 15),
+               "Invalid interpolated string. This interpolated string expression fill is empty, an expression was expected.")
+            |]
+
+        let code = """
+let xd = $"%A{  }" // empty expression
+"""
+        CompilerAssert.TypeCheckWithErrorsAndOptions  [| "--langversion:preview" |]
+            code
+            [|(FSharpErrorSeverity.Error, 3382, (2, 15, 2, 17),
+               "Invalid interpolated string. This interpolated string expression fill is empty, an expression was expected.")
             |]
 
     [<Test>]
@@ -818,29 +827,29 @@ let TripleInterpolatedInVerbatimInterpolated = $\"123{456}789{$\"\"\"012\"\"\"}3
         let code = "let x1 = $\"}\""
         CompilerAssert.TypeCheckWithErrorsAndOptions  [| "--langversion:preview" |]
             code
-            [|(FSharpErrorSeverity.Error, 3382, (1, 10, 1, 14),
+            [|(FSharpErrorSeverity.Error, 3383, (1, 10, 1, 14),
                "A '}' character must be escaped (by doubling) in an interpolated string.")|]
 
     [<Test>]
     let ``String interpolation extra right brace verbatim`` () =
         let code = "let x1 = @$\"}\""
         CompilerAssert.TypeCheckWithErrorsAndOptions  [| "--langversion:preview" |]
             code
-            [|(FSharpErrorSeverity.Error, 3382, (1, 10, 1, 15),
+            [|(FSharpErrorSeverity.Error, 3383, (1, 10, 1, 15),
                "A '}' character must be escaped (by doubling) in an interpolated string.")|]
 
     [<Test>]
     let ``String interpolation extra right brace triple`` () =
         let code = "let x1 = $\"\"\"}\"\"\""
         CompilerAssert.TypeCheckWithErrorsAndOptions  [| "--langversion:preview" |]
             code
-            [|(FSharpErrorSeverity.Error, 3382, (1, 10, 1, 18),
+            [|(FSharpErrorSeverity.Error, 3383, (1, 10, 1, 18),
                "A '}' character must be escaped (by doubling) in an interpolated string.")|]
 
     [<Test>]
     let ``String interpolation extra right brace single quote with hole`` () =
         let code = "let x1 = $\"{0}}\""
         CompilerAssert.TypeCheckWithErrorsAndOptions  [| "--langversion:preview" |]
             code
-            [|(FSharpErrorSeverity.Error, 3382, (1, 14, 1, 17),
+            [|(FSharpErrorSeverity.Error, 3383, (1, 14, 1, 17),
                "A '}' character must be escaped (by doubling) in an interpolated string.")|]