A diagnosis from the argument clinic (#20997)

[Parse] Warn if the same argument is specified more than once in @available

Author: beccadax

include/swift/AST/DiagnosticsParse.def

@@ -1349,6 +1349,8 @@ ERROR(attr_availability_unavailable_deprecated,none,
       "'%0' attribute cannot be both unconditionally 'unavailable' and "
       "'deprecated'", (StringRef))
 
+WARNING(attr_availability_invalid_duplicate,none,
+        "'%0' argument has already been specified", (StringRef))
 WARNING(attr_availability_unknown_platform,none,
       "unknown platform '%0' for attribute '%1'", (StringRef, StringRef))
 ERROR(attr_availability_invalid_renamed,none,

lib/Parse/ParseDecl.cpp

@@ -358,6 +358,7 @@ ParserResult<AvailableAttr> Parser::parseExtendedAvailabilitySpecList(
   while (HasUpcomingEntry) {
     SyntaxParsingContext EntryContext(SyntaxContext,
                                       SyntaxKind::AvailabilityArgument);
+    auto ArgumentLoc = Tok.getLoc();
     AnyAnnotations = true;
     StringRef ArgumentKindStr = Tok.getText();
     ParamIndex++;
@@ -382,8 +383,8 @@ ParserResult<AvailableAttr> Parser::parseExtendedAvailabilitySpecList(
     }
 
     if (ArgumentKind == IsInvalid) {
-      diagnose(Tok.getLoc(), diag::attr_availability_expected_option, AttrName)
-          .highlight(SourceRange(Tok.getLoc()));
+      diagnose(ArgumentLoc, diag::attr_availability_expected_option, AttrName)
+          .highlight(SourceRange(ArgumentLoc));
       if (Tok.is(tok::code_complete) && CodeCompletion) {
         CodeCompletion->completeDeclAttrParam(DAK_Available, ParamIndex);
         consumeToken(tok::code_complete);
@@ -395,6 +396,13 @@ ParserResult<AvailableAttr> Parser::parseExtendedAvailabilitySpecList(
 
     consumeToken();
 
+    auto diagnoseDuplicate = [&](bool WasEmpty) {
+      if (!WasEmpty) {
+        diagnose(ArgumentLoc, diag::attr_availability_invalid_duplicate,
+                 ArgumentKindStr);
+      }
+    };
+
     switch (ArgumentKind) {
     case IsMessage:
     case IsRenamed: {
@@ -427,6 +435,7 @@ ParserResult<AvailableAttr> Parser::parseExtendedAvailabilitySpecList(
       }
 
       if (ArgumentKind == IsMessage) {
+        diagnoseDuplicate(Message.empty());
         Message = Value.getValue();
       } else {
         ParsedDeclName parsedName = parseDeclName(Value.getValue());
@@ -435,6 +444,7 @@ ParserResult<AvailableAttr> Parser::parseExtendedAvailabilitySpecList(
           AnyArgumentInvalid = true;
           break;
         }
+        diagnoseDuplicate(Renamed.empty());
         Renamed = Value.getValue();
       }
 
@@ -476,6 +486,7 @@ ParserResult<AvailableAttr> Parser::parseExtendedAvailabilitySpecList(
               ? Introduced
               : (ArgumentKind == IsDeprecated) ? Deprecated : Obsoleted;
 
+      bool VerArgWasEmpty = VerArg.empty();
       if (parseVersionTuple(
               VerArg.Version, VerArg.Range,
               Diagnostic(diag::attr_availability_expected_version, AttrName))) {
@@ -484,6 +495,7 @@ ParserResult<AvailableAttr> Parser::parseExtendedAvailabilitySpecList(
           consumeToken();
       }
       VerArg.DelimiterLoc = DelimiterLoc;
+      diagnoseDuplicate(VerArgWasEmpty);
 
       SyntaxContext->createNodeInPlace(SyntaxKind::AvailabilityLabeledArgument);
 

test/attr/attr_availability.swift

@@ -1049,3 +1049,23 @@ struct SR8634_Struct: Equatable {
   @available(*, deprecated, message: "I must not be raised in synthesized code", renamed: "x")
   let a: Int
 }
+
+@available(*, deprecated, message: "This is a message", message: "This is another message")
+// expected-warning@-1 {{'message' argument has already been specified}}
+func rdar46348825_message() {}
+
+@available(*, deprecated, renamed: "rdar46348825_message", renamed: "unavailable_func_with_message")
+// expected-warning@-1 {{'renamed' argument has already been specified}}
+func rdar46348825_renamed() {}
+
+@available(swift, introduced: 4.0, introduced: 4.0)
+// expected-warning@-1 {{'introduced' argument has already been specified}}
+func rdar46348825_introduced() {}
+
+@available(swift, deprecated: 4.0, deprecated: 4.0)
+// expected-warning@-1 {{'deprecated' argument has already been specified}}
+func rdar46348825_deprecated() {}
+
+@available(swift, obsoleted: 4.0, obsoleted: 4.0)
+// expected-warning@-1 {{'obsoleted' argument has already been specified}}
+func rdar46348825_obsoleted() {}