Recursive functions should be marked when used from another function. Fixes http://llvm.org/PR7923.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@112045 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaExpr.cpp

@@ -7683,7 +7683,10 @@ void Sema::MarkDeclarationReferenced(SourceLocation Loc, Decl *D) {
     }
 
     // FIXME: keep track of references to static functions
-    Function->setUsed(true);
+
+    // Recursive functions should be marked when used from another function.
+    if (CurContext != Function)
+      Function->setUsed(true);
 
     return;
   }

test/Sema/warn-unused-function.c

@@ -44,3 +44,6 @@ static void f11(void) { }  // expected-warning{{unused}}
 
 static void f12(void) { }  // expected-warning{{unused}}
 static void f12(void);
+
+// PR7923
+static void unused(void) { unused(); }  // expected-warning{{unused}}