[Clang] fix missing source location for ':' error in macro-expanded case statements

Author: a-tarasyuk

clang/docs/ReleaseNotes.rst

@@ -689,6 +689,7 @@ Bug Fixes in This Version
 - Fixed type mismatch error when 'builtin-elementwise-math' arguments have different qualifiers, this should be well-formed. (#GH141397)
 - Constant evaluation now correctly runs the destructor of a variable declared in
   the second clause of a C-style ``for`` loop. (#GH139818)
+- Fixed incorrect diagnostic location for missing ``:`` in case statements expanded from macros. (#GH143216)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

clang/include/clang/Basic/DiagnosticCommonKinds.td

@@ -83,6 +83,7 @@ let CategoryName = "Parse Issue" in {
 def err_expected : Error<"expected %0">;
 def err_expected_either : Error<"expected %0 or %1">;
 def err_expected_after : Error<"expected %1 after %0">;
+def note_macro_expansion : Note<"expanded from macro '%0'">;
 
 def err_param_redefinition : Error<"redefinition of parameter %0">;
 def warn_method_param_redefinition : Warning<"redefinition of method parameter %0">;

clang/lib/Parse/ParseStmt.cpp

@@ -833,9 +833,23 @@ StmtResult Parser::ParseCaseStatement(ParsedStmtContext StmtCtx,
           << FixItHint::CreateReplacement(ColonLoc, ":");
     } else {
       SourceLocation ExpectedLoc = PP.getLocForEndOfToken(PrevTokLocation);
+      SourceLocation ExprLoc =
+          LHS.get() ? LHS.get()->getExprLoc() : SourceLocation();
+
+      if (ExpectedLoc.isInvalid() && ExprLoc.isMacroID()) {
+        ExpectedLoc = PP.getSourceManager().getSpellingLoc(ExprLoc);
+      }
+
       Diag(ExpectedLoc, diag::err_expected_after)
           << "'case'" << tok::colon
           << FixItHint::CreateInsertion(ExpectedLoc, ":");
+
+      if (ExprLoc.isMacroID()) {
+        Diag(ExprLoc, diag::note_macro_expansion)
+            << Lexer::getImmediateMacroNameForDiagnostics(
+                   ExprLoc, PP.getSourceManager(), getLangOpts());
+      }
+
       ColonLoc = ExpectedLoc;
     }
 

clang/test/Parser/switch-recovery.cpp

@@ -229,3 +229,16 @@ void fn1() {
     }
 } // expected-error{{expected statement}}
 }
+
+namespace GH143216 {
+#define FOO 1 case 3: // expected-error {{expected ':' after 'case'}}
+
+int f(int x) {
+  switch (x) {
+  case FOO // expected-note {{expanded from macro 'FOO'}}
+    return 0;
+  default:
+    return 1;
+  }
+}
+}