[clang] Suppress noreturn warning if last statement in a function is a throw (#145166)

Fixes https://github.com/llvm/llvm-project/issues/144952

1 files changed, 23 insertions, 1 deletions

diff --git a/clang/lib/Sema/AnalysisBasedWarnings.cpp b/clang/lib/Sema/AnalysisBasedWarnings.cpp
index 2a107a36..f3798bb 100644
--- a/clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -643,7 +643,7 @@ static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
       ReturnsVoid = CBody->getFallthroughHandler() != nullptr;
     else
       ReturnsVoid = FD->getReturnType()->isVoidType();
-    HasNoReturn = FD->isNoReturn();
+    HasNoReturn = FD->isNoReturn() || FD->hasAttr<InferredNoReturnAttr>();
   }
   else if (const auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
     ReturnsVoid = MD->getReturnType()->isVoidType();
@@ -681,6 +681,28 @@ static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
       if (CD.diag_FallThrough_HasNoReturn)
         S.Diag(RBrace, CD.diag_FallThrough_HasNoReturn) << CD.FunKind;
     } else if (!ReturnsVoid && CD.diag_FallThrough_ReturnsNonVoid) {
+      // If the final statement is a call to an always-throwing function,
+      // don't warn about the fall-through.
+      if (const auto *FD = D->getAsFunction()) {
+        if (const auto *CS = dyn_cast<CompoundStmt>(Body);
+            CS && !CS->body_empty()) {
+          const Stmt *LastStmt = CS->body_back();
+          // Unwrap ExprWithCleanups if necessary.
+          if (const auto *EWC = dyn_cast<ExprWithCleanups>(LastStmt)) {
+            LastStmt = EWC->getSubExpr();
+          }
+          if (const auto *CE = dyn_cast<CallExpr>(LastStmt)) {
+            if (const FunctionDecl *Callee = CE->getDirectCallee();
+                Callee && Callee->hasAttr<InferredNoReturnAttr>()) {
+              return; // Don't warn about fall-through.
+            }
+          }
+          // Direct throw.
+          if (isa<CXXThrowExpr>(LastStmt)) {
+            return; // Don't warn about fall-through.
+          }
+        }
+      }
       bool NotInAllControlPaths = FallThroughType == MaybeFallThrough;
       S.Diag(RBrace, CD.diag_FallThrough_ReturnsNonVoid)
           << CD.FunKind << NotInAllControlPaths;