1 files changed, 71 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 43e61d3429f..5f5f4c8d044 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -6107,6 +6107,77 @@ Sema::BuildCompoundLiteralExpr(SourceLocation LParenLoc, TypeSourceInfo *TInfo,
 ExprResult
 Sema::ActOnInitList(SourceLocation LBraceLoc, MultiExprArg InitArgList,
                     SourceLocation RBraceLoc) {
+  // Only produce each kind of designated initialization diagnostic once.
+  SourceLocation FirstDesignator;
+  bool DiagnosedArrayDesignator = false;
+  bool DiagnosedNestedDesignator = false;
+  bool DiagnosedMixedDesignator = false;
+
+  // Check that any designated initializers are syntactically valid in the
+  // current language mode.
+  for (unsigned I = 0, E = InitArgList.size(); I != E; ++I) {
+    if (auto *DIE = dyn_cast<DesignatedInitExpr>(InitArgList[I])) {
+      if (FirstDesignator.isInvalid())
+        FirstDesignator = DIE->getBeginLoc();
+
+      if (!getLangOpts().CPlusPlus)
+        break;
+
+      if (!DiagnosedNestedDesignator && DIE->size() > 1) {
+        DiagnosedNestedDesignator = true;
+        Diag(DIE->getBeginLoc(), diag::ext_designated_init_nested)
+          << DIE->getDesignatorsSourceRange();
+      }
+
+      for (auto &Desig : DIE->designators()) {
+        if (!Desig.isFieldDesignator() && !DiagnosedArrayDesignator) {
+          DiagnosedArrayDesignator = true;
+          Diag(Desig.getBeginLoc(), diag::ext_designated_init_array)
+            << Desig.getSourceRange();
+        }
+      }
+
+      if (!DiagnosedMixedDesignator &&
+          !isa<DesignatedInitExpr>(InitArgList[0])) {
+        DiagnosedMixedDesignator = true;
+        Diag(DIE->getBeginLoc(), diag::ext_designated_init_mixed)
+          << DIE->getSourceRange();
+        Diag(InitArgList[0]->getBeginLoc(), diag::note_designated_init_mixed)
+          << InitArgList[0]->getSourceRange();
+      }
+    } else if (getLangOpts().CPlusPlus && !DiagnosedMixedDesignator &&
+               isa<DesignatedInitExpr>(InitArgList[0])) {
+      DiagnosedMixedDesignator = true;
+      auto *DIE = cast<DesignatedInitExpr>(InitArgList[0]);
+      Diag(DIE->getBeginLoc(), diag::ext_designated_init_mixed)
+        << DIE->getSourceRange();
+      Diag(InitArgList[I]->getBeginLoc(), diag::note_designated_init_mixed)
+        << InitArgList[I]->getSourceRange();
+    }
+  }
+
+  if (FirstDesignator.isValid()) {
+    // Only diagnose designated initiaization as a C++20 extension if we didn't
+    // already diagnose use of (non-C++20) C99 designator syntax.
+    if (getLangOpts().CPlusPlus && !DiagnosedArrayDesignator &&
+        !DiagnosedNestedDesignator && !DiagnosedMixedDesignator) {
+      Diag(FirstDesignator, getLangOpts().CPlusPlus2a
+                                ? diag::warn_cxx17_compat_designated_init
+                                : diag::ext_cxx_designated_init);
+    } else if (!getLangOpts().CPlusPlus && !getLangOpts().C99) {
+      Diag(FirstDesignator, diag::ext_designated_init);
+    }
+  }
+
+  return BuildInitList(LBraceLoc, InitArgList, RBraceLoc);
+}
+
+ExprResult
+Sema::BuildInitList(SourceLocation LBraceLoc, MultiExprArg InitArgList,
+                    SourceLocation RBraceLoc) {
+  // Semantic analysis for initializers is done by ActOnDeclarator() and
+  // CheckInitializer() - it requires knowledge of the object being initialized.
+
   // Immediately handle non-overload placeholders.  Overloads can be
   // resolved contextually, but everything else here can't.
   for (unsigned I = 0, E = InitArgList.size(); I != E; ++I) {
@@ -6121,9 +6192,6 @@ Sema::ActOnInitList(SourceLocation LBraceLoc, MultiExprArg InitArgList,
     }
   }
 
-  // Semantic analysis for initializers is done by ActOnDeclarator() and
-  // CheckInitializer() - it requires knowledge of the object being initialized.
-
   InitListExpr *E = new (Context) InitListExpr(Context, LBraceLoc, InitArgList,
                                                RBraceLoc);
   E->setType(Context.VoidTy); // FIXME: just a place holder for now.