[clang] [clang-tools-extra] [Clang] Implement CWG2813: Class member access with prvalues (PR #120223)

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``````````bash
git-clang-format --diff 0693b9e9ccdec5f09a3080b1bec73f5004a8dfa3 fb9570cbaa8ee6565b23f0183002b848d0e6f35d --extensions cpp,h -- clang-tools-extra/clangd/unittests/DumpASTTests.cpp clang/include/clang/Sema/Sema.h clang/lib/AST/Expr.cpp clang/lib/Sema/SemaExprMember.cpp clang/lib/Sema/SemaOverload.cpp clang/lib/Sema/SemaStmt.cpp clang/test/AST/ast-dump-for-range-lifetime.cpp clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p2.cpp clang/test/CXX/drs/cwg28xx.cpp clang/test/CodeGenCXX/cxx2b-deducing-this.cpp clang/test/SemaCXX/cxx2b-deducing-this.cpp clang/test/SemaCXX/ms-property.cpp
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View the diff from clang-format here.
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``````````diff
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index cd09d748f0..6c32e17bf0 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -10659,9 +10659,9 @@ public:
                            SourceLocation EndLoc);
   void ActOnForEachDeclStmt(DeclGroupPtrTy Decl);
 
-  /// DiagnoseDiscardedExprMarkedNodiscard - Given an expression that is semantically
-  /// a discarded-value expression, diagnose if any [[nodiscard]] value
-  /// has been discarded
+  /// DiagnoseDiscardedExprMarkedNodiscard - Given an expression that is
+  /// semantically a discarded-value expression, diagnose if any [[nodiscard]]
+  /// value has been discarded
   void DiagnoseDiscardedExprMarkedNodiscard(const Expr *E);
 
   /// DiagnoseUnusedExprResult - If the statement passed in is an expression
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 5c35f44e38..8f45a10ecc 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -230,8 +230,8 @@ namespace {
 
 // Diagnoses unused expressions that call functions marked [[nodiscard]],
 // [[gnu::warn_unused_result]] and similar.
-// Additionally, a DiagID can be provided to emit a warning in additional contexts
-// (such as for an unused LHS of a comma expression)
+// Additionally, a DiagID can be provided to emit a warning in additional
+// contexts (such as for an unused LHS of a comma expression)
 void DiagnoseUnused(Sema &S, const Expr *E, std::optional<unsigned> DiagID) {
   bool NoDiscardOnly = !DiagID.has_value();
 
@@ -332,8 +332,8 @@ void DiagnoseUnused(Sema &S, const Expr *E, std::optional<unsigned> DiagID) {
   } else if (const auto *ILE = dyn_cast<InitListExpr>(E)) {
     if (const TagDecl *TD = ILE->getType()->getAsTagDecl()) {
 
-      if (DiagnoseNoDiscard(S, TD, TD->getAttr<WarnUnusedResultAttr>(), Loc,
-                            R1, R2, /*isCtor=*/false))
+      if (DiagnoseNoDiscard(S, TD, TD->getAttr<WarnUnusedResultAttr>(), Loc, R1,
+                            R2, /*isCtor=*/false))
         return;
     }
   } else if (ShouldSuppress)
@@ -347,7 +347,8 @@ void DiagnoseUnused(Sema &S, const Expr *E, std::optional<unsigned> DiagID) {
     }
     const ObjCMethodDecl *MD = ME->getMethodDecl();
     if (MD) {
-      if (DiagnoseNoDiscard(S, nullptr, MD->getAttr<WarnUnusedResultAttr>(), Loc, R1, R2,
+      if (DiagnoseNoDiscard(S, nullptr, MD->getAttr<WarnUnusedResultAttr>(),
+                            Loc, R1, R2,
                             /*isCtor=*/false))
         return;
     }
@@ -403,7 +404,7 @@ void DiagnoseUnused(Sema &S, const Expr *E, std::optional<unsigned> DiagID) {
 
   // Don't diagnose discarded left of dot in static class member access
   // because its type is "used" to determine the class to access
-  //if (DiagID == diag::warn_discarded_class_member_access)
+  // if (DiagID == diag::warn_discarded_class_member_access)
   //  return;
 
   // Do not diagnose use of a comma operator in a SFINAE context because the

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https://github.com/llvm/llvm-project/pull/120223