Try to fix build with clang trunk

I don't have trunk, but this should work.
Maybe some header missing. Reporter to test.

CCBUG: 403083

2 files changed, 24 insertions, 1 deletions

diff --git a/src/SourceCompatibilityHelpers.h b/src/SourceCompatibilityHelpers.h
index 9b1fc772..440b1226 100644
--- a/src/SourceCompatibilityHelpers.h
+++ b/src/SourceCompatibilityHelpers.h
@@ -25,6 +25,8 @@
 
 #include <clang/Basic/SourceLocation.h>
 #include <clang/Basic/SourceManager.h>
+#include <clang/AST/Decl.h>
+#include <clang/AST/Expr.h>
 
 namespace clazy {
 
@@ -58,6 +60,27 @@ inline clang::CharSourceRange getImmediateExpansionRange(clang::SourceLocation m
 #endif
 }
 
+inline bool hasUnusedResultAttr(clang::FunctionDecl *func)
+{
+#if LLVM_VERSION_MAJOR >= 8
+    auto RetType = func->getReturnType();
+    if (const auto *Ret = RetType->getAsRecordDecl()) {
+        if (const auto *R = Ret->getAttr<clang::WarnUnusedResultAttr>())
+            return R != nullptr;
+    } else if (const auto *ET = RetType->getAs<clang::EnumType>()) {
+        if (const EnumDecl *ED = ET->getDecl()) {
+            if (const auto *R = ED->getAttr<clang::WarnUnusedResultAttr>())
+                return R != nullptr;
+        }
+    }
+    return clang::getAttr<clang::WarnUnusedResultAttr>() != nullptr;
+#else
+    return func->hasUnusedResultAttr();
+#endif
+
+}
+
+
 }
 
 #endif
diff --git a/src/checks/manuallevel/qrequiredresult-candidates.cpp b/src/checks/manuallevel/qrequiredresult-candidates.cpp
index 40501a38..912dbaa0 100644
--- a/src/checks/manuallevel/qrequiredresult-candidates.cpp
+++ b/src/checks/manuallevel/qrequiredresult-candidates.cpp
@@ -45,7 +45,7 @@ void QRequiredResultCandidates::VisitDecl(clang::Decl *decl)
     if (method->isThisDeclarationADefinition() && !method->hasInlineBody()) // Don't warn twice
         return;
 
-    if (method->hasUnusedResultAttr()) // Also catches nodiscard
+    if (clazy::hasUnusedResultAttr(method)) // Also catches nodiscard
         return;
 
     if (method->getAccess() == AS_private) // We're only interested on our public API