[Parse] Move standalone_dollar_identifier diagnosis to Parser. Resolves SR-13092.

Author: mininny

include/swift/Parse/Parser.h

@@ -567,8 +567,8 @@ class Parser {
     if (Result)
       *Result = Context.getIdentifier(Tok.getText());
 
-    if (Tok.getText()[0] == '$' && !allowDollarIdentifier)
-      diagnoseDollarIdentifier(Tok);
+    if (Tok.getText()[0] == '$')
+      diagnoseDollarIdentifier(Tok, allowDollarIdentifier);
 
     return consumeToken();
   }
@@ -588,11 +588,22 @@ class Parser {
 
   /// When we have a token that is an identifier starting with '$',
   /// diagnose it if not permitted in this mode.
-  void diagnoseDollarIdentifier(const Token &tok) {
+  void diagnoseDollarIdentifier(const Token &tok,
+                                bool allowDollarIdentifier = false) {
     assert(tok.getText()[0] == '$');
 
-    if (tok.getText().size() == 1 ||
-        Context.LangOpts.EnableDollarIdentifiers ||
+    // If '$' is not guarded by backticks, offer
+    // to replace it with '`$`'.
+    if (Tok.getRawText() == "$") {
+      diagnose(Tok.getLoc(), diag::standalone_dollar_identifier)
+          .fixItReplace(Tok.getLoc(), "`$`");
+      return;
+    }
+
+    if (allowDollarIdentifier)
+      return;
+
+    if (tok.getText().size() == 1 || Context.LangOpts.EnableDollarIdentifiers ||
         isInSILMode() || L->isSwiftInterface())
       return;
 

lib/Parse/Lexer.cpp

@@ -932,10 +932,8 @@ void Lexer::lexDollarIdent() {
     break;
   }
 
+  // If there is a standalone '$', treat it like an identifier.
   if (CurPtr == tokStart + 1) {
-    // It is an error to see a standalone '$'. Offer to replace '$' with '`$`'.
-    diagnose(tokStart, diag::standalone_dollar_identifier)
-      .fixItReplaceChars(getSourceLoc(tokStart), getSourceLoc(CurPtr), "`$`");
     return formToken(tok::identifier, tokStart);
   }
 

lib/Parse/ParseDecl.cpp

@@ -7719,11 +7719,13 @@ Parser::parseDeclOperator(ParseDeclOptions Flags, DeclAttributes &Attributes) {
   bool AllowTopLevel = Flags.contains(PD_AllowTopLevel);
 
   const auto maybeDiagnoseInvalidCharInOperatorName = [this](const Token &Tk) {
-    if (Tk.is(tok::identifier) &&
-        DeclAttribute::getAttrKindFromString(Tk.getText()) ==
-          DeclAttrKind::DAK_Count) {
-      diagnose(Tk, diag::identifier_within_operator_name, Tk.getText());
-      return true;
+    if (Tk.is(tok::identifier)) {
+      if (Tk.getText().equals("$") ||
+          DeclAttribute::getAttrKindFromString(Tk.getText()) ==
+              DeclAttrKind::DAK_Count) {
+        diagnose(Tk, diag::identifier_within_operator_name, Tk.getText());
+        return true;
+      }
     } else if (Tk.isNot(tok::colon, tok::l_brace, tok::semi) &&
                Tk.isPunctuation()) {
       diagnose(Tk, diag::operator_name_invalid_char,

test/Parse/dollar_identifier.swift

@@ -83,3 +83,6 @@ struct S {
 }
 
 let _ = S().$café // Okay
+
+infix operator $ // expected-error{{'$' is considered an identifier and must not appear within an operator name}} // SR-13092
+infix operator `$` // expected-error{{'$' is considered an identifier and must not appear within an operator name}} // SR-13092