Merge pull request swiftlang#28951 from kitaisreal/separated-do-while-blocks-diagnostic-correction

[Parse]: Separate do and while blocks diagnostics

Author: rintaro

include/swift/AST/DiagnosticsParse.def

@@ -1037,7 +1037,11 @@ ERROR(expected_expr_repeat_while,PointsToFirstBadToken,
       "expected expression in 'repeat-while' condition", ())
 
 ERROR(do_while_now_repeat_while,none,
-      "'do-while' statement is not allowed; use 'repeat-while' instead", ())
+      "'do-while' statement is not allowed", ())
+NOTE(do_while_expected_repeat_while, none,
+      "did you mean 'repeat-while' statement?", ())
+NOTE(do_while_expected_separate_stmt, none,
+      "did you mean separate 'do' and 'while' statements?", ())
 
 // Do/Catch Statement
 ERROR(expected_lbrace_after_do,PointsToFirstBadToken,

lib/Parse/ParseStmt.cpp

@@ -1917,18 +1917,21 @@ ParserResult<Stmt> Parser::parseStmtDo(LabeledStmtInfo labelInfo) {
       DoCatchStmt::create(Context, labelInfo, doLoc, body.get(), allClauses));
   }
 
-  SourceLoc whileLoc;
-
-  // If we don't see a 'while', this is just the bare 'do' scoping
-  // statement.
-  if (!consumeIf(tok::kw_while, whileLoc)) {
+  // If we dont see a 'while' or see a 'while' that starts
+  // from new line. This is just the bare `do` scoping statement.
+  if (Tok.getKind() != tok::kw_while || Tok.isAtStartOfLine()) {
     return makeParserResult(status,
-                         new (Context) DoStmt(labelInfo, doLoc, body.get()));
+                            new (Context) DoStmt(labelInfo, doLoc, body.get()));
   }
-
+  SourceLoc whileLoc = Tok.getLoc();
   // But if we do, advise the programmer that it's 'repeat' now.
-  diagnose(doLoc, diag::do_while_now_repeat_while)
+  diagnose(doLoc, diag::do_while_now_repeat_while);
+  diagnose(doLoc, diag::do_while_expected_repeat_while)
     .fixItReplace(doLoc, "repeat");
+  diagnose(doLoc, diag::do_while_expected_separate_stmt)
+    .fixItInsert(whileLoc, "\n");
+
+  consumeToken(tok::kw_while);
   status.setIsParseError();
   ParserResult<Expr> condition;
   if (Tok.is(tok::l_brace)) {

test/stmt/statements.swift

@@ -235,11 +235,23 @@ func DoStmt() {
   }
 }
 
-func DoWhileStmt() {
-  do { // expected-error {{'do-while' statement is not allowed; use 'repeat-while' instead}} {{3-5=repeat}}
+
+func DoWhileStmt1() {
+  do { // expected-error {{'do-while' statement is not allowed}}
+  // expected-note@-1 {{did you mean 'repeat-while' statement?}} {{3-5=repeat}}
+  // expected-note@-2 {{did you mean separate 'do' and 'while' statements?}} {{5-5=\n}}
   } while true
 }
 
+func DoWhileStmt2() {
+  do {
+
+  }
+  while true {
+
+  }
+}
+
 //===--- Repeat-while statement.
 
 func RepeatWhileStmt1() {