Diagnose an unused result from a call through a function pointer whose return type is marked [[nodiscard]].

When a function returns a type and that type was declared [[nodiscard]], we diagnose any unused results from that call as though the function were marked nodiscard. The same behavior should apply to calls through a function pointer.

This addresses PR31526.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@350317 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 0 deletions

diff --git a/include/clang/AST/Expr.h b/include/clang/AST/Expr.h
index 156782b330..025ef0642a 100644
--- a/include/clang/AST/Expr.h
+++ b/include/clang/AST/Expr.h
@@ -2624,6 +2624,15 @@ public:
   /// type.
   QualType getCallReturnType(const ASTContext &Ctx) const;
 
+  /// Returns the WarnUnusedResultAttr that is either declared on the called
+  /// function, or its return type declaration.
+  const Attr *getUnusedResultAttr(const ASTContext &Ctx) const;
+
+  /// Returns true if this call expression should warn on unused results.
+  bool hasUnusedResultAttr(const ASTContext &Ctx) const {
+    return getUnusedResultAttr(Ctx) != nullptr;
+  }
+
   SourceLocation getRParenLoc() const { return RParenLoc; }
   void setRParenLoc(SourceLocation L) { RParenLoc = L; }