[Parse] Adjust diagnostics message for duplicated effects specifiers

Author: rintaro

include/swift/AST/DiagnosticsParse.def

@@ -732,8 +732,7 @@ ERROR(rethrowing_function_type,none,
       "only function declarations may be marked 'rethrows'; "
       "did you mean 'throws'?", ())
 ERROR(async_or_throws_in_wrong_position,none,
-      "%select{'throws'|'rethrows'|'async'}0 may only occur before '->'",
-      (unsigned))
+      "'%0' may only occur before '->'", (StringRef))
 ERROR(throw_in_function_type,none,
       "expected throwing specifier; did you mean 'throws'?", ())
 ERROR(expected_type_before_arrow,none,
@@ -748,8 +747,8 @@ ERROR(expected_dynamic_func_attr,none,
 ERROR(async_after_throws,none,
       "'async' must precede %select{'throws'|'rethrows'}0", (bool))
 ERROR(async_init,none, "initializer cannot be marked 'async'", ())
-ERROR(duplicate_effect_specifier,none,
-      "unexpected '%0' specifier", (StringRef))
+ERROR(duplicate_effects_specifier,none,
+      "'%0' has already been specified", (StringRef))
 
 // Enum Types
 ERROR(expected_expr_enum_case_raw_value,PointsToFirstBadToken,

lib/Parse/ParseExpr.cpp

@@ -139,7 +139,7 @@ ParserResult<Expr> Parser::parseExprArrow() {
     assert(throwsLoc.isValid() || asyncLoc.isValid());
     diagnose(throwsLoc.isValid() ? throwsLoc : asyncLoc,
              diag::async_or_throws_in_wrong_position,
-             throwsLoc.isValid() ? 0 : 2);
+             throwsLoc.isValid() ? "throws" : "async");
     return nullptr;
   }
 

lib/Parse/ParsePattern.cpp

@@ -848,14 +848,15 @@ ParserStatus Parser::parseEffectsSpecifiers(SourceLoc existingArrowLoc,
         Tok.isContextualKeyword("async")) {
 
       if (asyncLoc.isValid()) {
-        diagnose(Tok, diag::duplicate_effect_specifier, Tok.getText())
+        diagnose(Tok, diag::duplicate_effects_specifier, Tok.getText())
+            .highlight(asyncLoc)
             .fixItRemove(Tok.getLoc());
       } else if (existingArrowLoc.isValid()) {
         SourceLoc insertLoc = existingArrowLoc;
         if (throwsLoc.isValid() &&
             SourceMgr.isBeforeInBuffer(throwsLoc, insertLoc))
           insertLoc = throwsLoc;
-        diagnose(Tok, diag::async_or_throws_in_wrong_position, 2)
+        diagnose(Tok, diag::async_or_throws_in_wrong_position, "async")
             .fixItRemove(Tok.getLoc())
             .fixItInsert(insertLoc, "async ");
       } else if (throwsLoc.isValid()) {
@@ -877,7 +878,8 @@ ParserStatus Parser::parseEffectsSpecifiers(SourceLoc existingArrowLoc,
       bool isRethrows = Tok.is(tok::kw_rethrows);
 
       if (throwsLoc.isValid()) {
-        diagnose(Tok, diag::duplicate_effect_specifier, Tok.getText())
+        diagnose(Tok, diag::duplicate_effects_specifier, Tok.getText())
+            .highlight(throwsLoc)
             .fixItRemove(Tok.getLoc());
       } else if (Tok.isAny(tok::kw_throw, tok::kw_try)) {
         // Replace 'throw' or 'try' with 'throws'.
@@ -888,8 +890,7 @@ ParserStatus Parser::parseEffectsSpecifiers(SourceLoc existingArrowLoc,
         diagnose(Tok, diag::rethrowing_function_type)
             .fixItReplace(Tok.getLoc(), "throws");
       } else if (existingArrowLoc.isValid()) {
-        diagnose(Tok, diag::async_or_throws_in_wrong_position,
-                 rethrows ? (isRethrows ? 1 : 0) : 0)
+        diagnose(Tok, diag::async_or_throws_in_wrong_position, Tok.getText())
             .fixItRemove(Tok.getLoc())
             .fixItInsert(existingArrowLoc, (Tok.getText() + " ").str());
       }

test/Parse/async.swift

@@ -23,9 +23,9 @@ func asyncGlobal6() -> Int throws async { }
 func asyncGlobal7() throws -> Int async { } // expected-error{{'async' may only occur before '->'}}{{35-41=}}{{21-21=async }}
 
 func asyncGlobal8() async throws async -> async Int async {}
-// expected-error@-1{{unexpected 'async' specifier}} {{34-40=}}
-// expected-error@-2{{unexpected 'async' specifier}} {{43-49=}}
-// expected-error@-3{{unexpected 'async' specifier}} {{53-59=}}
+// expected-error@-1{{'async' has already been specified}} {{34-40=}}
+// expected-error@-2{{'async' has already been specified}} {{43-49=}}
+// expected-error@-3{{'async' has already been specified}} {{53-59=}}
 
 class X {
   init() async { } // expected-error{{initializer cannot be marked 'async'}}

test/Parse/errors.swift

@@ -121,20 +121,20 @@ func postThrows3() {
 }
 
 func dupThrows1() throws rethrows -> throws Int throw {}
-// expected-error@-1 {{unexpected 'rethrows' specifier}} {{26-35=}}
-// expected-error@-2 {{unexpected 'throws' specifier}} {{38-45=}}
-// expected-error@-3 {{unexpected 'throw' specifier}} {{49-55=}}
+// expected-error@-1 {{'rethrows' has already been specified}} {{26-35=}}
+// expected-error@-2 {{'throws' has already been specified}} {{38-45=}}
+// expected-error@-3 {{'throw' has already been specified}} {{49-55=}}
 
 func dupThrows2(_ f: () throws -> rethrows Int) {}
-// expected-error@-1 {{unexpected 'rethrows' specifier}} {{35-44=}}
+// expected-error@-1 {{'rethrows' has already been specified}} {{35-44=}}
 
 func dupThrows3() {
   _ = { () try throws in }
 // expected-error@-1 {{expected throwing specifier; did you mean 'throws'?}} {{12-15=throws}}
-// expected-error@-2 {{unexpected 'throws' specifier}} {{16-23=}}
+// expected-error@-2 {{'throws' has already been specified}} {{16-23=}}
 
   _ = { () throws -> Int throws in }
-// expected-error@-1 {{unexpected 'throws' specifier}} {{26-33=}}
+// expected-error@-1 {{'throws' has already been specified}} {{26-33=}}
 }
 
 func incompleteThrowType() {