test/Analysis/dead-stores.cpp

   1 // RUN: %clang_cc1 -analyze -analyzer-experimental-internal-checks -analyzer-checker=core.DeadStores -verify -Wno-unreachable-code %s
   2 // RUN: %clang_cc1 -analyze -analyzer-experimental-internal-checks -analyzer-check-objc-mem -analyzer-store=basic -analyzer-constraints=basic -analyzer-checker=core.DeadStores -verify -Wno-unreachable-code %s
   3 // RUN: %clang_cc1 -analyze -analyzer-experimental-internal-checks -analyzer-check-objc-mem -analyzer-store=basic -analyzer-constraints=range -analyzer-checker=core.DeadStores -verify -Wno-unreachable-code %s
   4 // RUN: %clang_cc1 -analyze -analyzer-experimental-internal-checks -analyzer-check-objc-mem -analyzer-store=region -analyzer-constraints=basic -analyzer-checker=core.DeadStores -verify -Wno-unreachable-code %s
   5 // RUN: %clang_cc1 -analyze -analyzer-experimental-internal-checks -analyzer-check-objc-mem -analyzer-store=region -analyzer-constraints=range -analyzer-checker=core.DeadStores -verify -Wno-unreachable-code %s
   6
   7 //===----------------------------------------------------------------------===//
   8 // Basic dead store checking (but in C++ mode).
   9 //===----------------------------------------------------------------------===//
  10
  11 int j;
  12 void test1() {
  13   int x = 4;
  14
  15   x = x + 1; // expected-warning{{never read}}
  16
  17   switch (j) {
  18   case 1:
  19     throw 1;
  20     (void)x;
  21     break;
  22   }
  23 }
  24
  25 //===----------------------------------------------------------------------===//
  26 // Dead store checking involving constructors.
  27 //===----------------------------------------------------------------------===//
  28
  29 class Test2 {
  30   int &x;
  31 public:
  32   Test2(int &y) : x(y) {}
  33   ~Test2() { ++x; }
  34 };
  35
  36 int test2(int x) {
  37   { Test2 a(x); } // no-warning
  38   return x;
  39 }
  40
  41 //===----------------------------------------------------------------------===//
  42 // Dead store checking involving CXXTemporaryExprs
  43 //===----------------------------------------------------------------------===//
  44
  45 namespace TestTemp {
  46   template<typename _Tp>
  47   class pencil {
  48   public:
  49     ~pencil() throw() {}
  50   };
  51   template<typename _Tp, typename _Number2> struct _Row_base {
  52     _Row_base(const pencil<_Tp>& x) {}
  53   };
  54   template<typename _Tp, typename _Number2 = TestTemp::pencil<_Tp> >
  55   class row : protected _Row_base<_Tp, _Number2>     {
  56     typedef _Row_base<_Tp, _Number2> _Base;
  57     typedef _Number2 pencil_type;
  58   public:
  59     explicit row(const pencil_type& __a = pencil_type()) : _Base(__a) {}
  60   };
  61 }
  62
  63 void test2_b() {
  64   TestTemp::row<const char*> x; // no-warning
  65 }
  66
  67 //===----------------------------------------------------------------------===//
  68 // Test references.
  69 //===----------------------------------------------------------------------===//
  70
  71 void test3_a(int x) {
  72    x = x + 1; // expected-warning{{never read}}
  73 }
  74
  75 void test3_b(int &x) {
  76   x = x + 1; // no-warninge
  77 }
  78
  79 void test3_c(int x) {
  80   int &y = x;
  81   // Shows the limitation of dead stores tracking.  The write is really
  82   // dead since the value cannot escape the function.
  83   ++y; // no-warning
  84 }
  85
  86 void test3_d(int &x) {
  87   int &y = x;
  88   ++y; // no-warning
  89 }
  90
  91 void test3_e(int &x) {
  92   int &y = x;
  93 }
  94
  95 //===----------------------------------------------------------------------===//
  96 // Dead stores involving 'new'
  97 //===----------------------------------------------------------------------===//
  98
  99 static void test_new(unsigned n) {
 100   char **p = new char* [n]; // expected-warning{{never read}}
 101 }
 102
 103 //===----------------------------------------------------------------------===//
 104 // Dead stores in namespaces.
 105 //===----------------------------------------------------------------------===//
 106
 107 namespace foo {
 108   int test_4(int x) {
 109     x = 2; // expected-warning{{Value stored to 'x' is never read}}
 110     x = 2;
 111     return x;
 112   }
 113 }
 114