From: Argyrios Kyrtzidis <akyrtzi@gmail.com>
Date: Sun, 19 Sep 2010 21:21:10 +0000 (+0000)
Subject: Warn when an expression result in a LabelStmt is unused.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d2827af6f96d441d72315dbe6d8505c3be0f2aa6;p=clang

Warn when an expression result in a LabelStmt is unused.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@114314 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 4c6822c041..b31ec2314d 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -1225,9 +1225,13 @@ bool Expr::isUnusedResultAWarning(SourceLocation &Loc, SourceRange &R1,
     // however, if the result of the stmt expr is dead, we don't want to emit a
     // warning.
     const CompoundStmt *CS = cast<StmtExpr>(this)->getSubStmt();
-    if (!CS->body_empty())
+    if (!CS->body_empty()) {
       if (const Expr *E = dyn_cast<Expr>(CS->body_back()))
         return E->isUnusedResultAWarning(Loc, R1, R2, Ctx);
+      if (const LabelStmt *Label = dyn_cast<LabelStmt>(CS->body_back()))
+        if (const Expr *E = dyn_cast<Expr>(Label->getSubStmt()))
+          return E->isUnusedResultAWarning(Loc, R1, R2, Ctx);
+    }
 
     if (getType()->isVoidType())
       return false;
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 8ec12a460d..47ea4f2c25 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -67,6 +67,9 @@ void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
 }
 
 void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
+  if (const LabelStmt *Label = dyn_cast_or_null<LabelStmt>(S))
+    return DiagnoseUnusedExprResult(Label->getSubStmt());
+
   const Expr *E = dyn_cast_or_null<Expr>(S);
   if (!E)
     return;
diff --git a/test/Sema/warn-unused-value.c b/test/Sema/warn-unused-value.c
index 1a7e745785..7c36b6983e 100644
--- a/test/Sema/warn-unused-value.c
+++ b/test/Sema/warn-unused-value.c
@@ -52,6 +52,9 @@ void pr4806() {
   volatile int* pj = &j;
   *pi;              // expected-warning {{expression result unused}}
   *pj;
+
+  foo_label:
+  i;                // expected-warning {{expression result unused}}
 }
 
 // Don't warn about unused '||', '&&' expressions that contain assignments.