clang/test/SemaCXX/varargs.cpp

   1 // RUN: %clang_cc1 -std=c++03 -Wno-c++11-extensions -triple i386-pc-unknown -verify %s
   2 // RUN: %clang_cc1 -std=c++11 -triple x86_64-apple-darwin9 -verify %s
   3
   4 __builtin_va_list ap;
   5
   6 class string;
   7 void f(const string& s, ...) {  // expected-note {{parameter of type 'const string &' is declared here}}
   8   __builtin_va_start(ap, s); // expected-warning {{passing an object of reference type to 'va_start' has undefined behavior}}
   9 }
  10
  11 void g(register int i, ...) { // expected-warning 0-1{{deprecated}}
  12   __builtin_va_start(ap, i); // UB in C, OK in C++
  13 }
  14
  15 // Don't crash when there is no last parameter.
  16 void no_params(...) {
  17   int a;
  18   __builtin_va_start(ap, a); // expected-warning {{second argument to 'va_start' is not the last named parameter}}
  19 }
  20
  21 // Reject this. The __builtin_va_start would execute in Foo's non-variadic
  22 // default ctor.
  23 void record_context(int a, ...) {
  24   struct Foo {
  25     // expected-error@+2 {{'va_start' cannot be used outside a function}}
  26     // expected-error@+1 {{default argument references parameter 'a'}}
  27     void meth(int a, int b = (__builtin_va_start(ap, a), 0)) {}
  28   };
  29 }
  30
  31 // Ensure the correct behavior for promotable type UB checking.
  32 void promotable(int a, ...) {
  33   enum Unscoped1 { One = 0x7FFFFFFF };
  34   (void)__builtin_va_arg(ap, Unscoped1); // ok
  35
  36   enum Unscoped2 { Two = 0xFFFFFFFF };
  37   (void)__builtin_va_arg(ap, Unscoped2); // ok
  38
  39   enum class Scoped { Three };
  40   (void)__builtin_va_arg(ap, Scoped); // ok
  41
  42   enum Fixed : int { Four };
  43   (void)__builtin_va_arg(ap, Fixed); // ok
  44
  45   enum FixedSmall : char { Five };
  46   (void)__builtin_va_arg(ap, FixedSmall); // expected-warning {{second argument to 'va_arg' is of promotable type 'FixedSmall'; this va_arg has undefined behavior because arguments will be promoted to 'int'}}
  47
  48   enum FixedLarge : long long { Six };
  49   (void)__builtin_va_arg(ap, FixedLarge); // ok
  50
  51   // Ensure that qualifiers are ignored.
  52   (void)__builtin_va_arg(ap, const volatile int);  // ok
  53
  54   // Ensure that signed vs unsigned doesn't matter either.
  55   (void)__builtin_va_arg(ap, unsigned int);
  56
  57   (void)__builtin_va_arg(ap, bool); // expected-warning {{second argument to 'va_arg' is of promotable type 'bool'; this va_arg has undefined behavior because arguments will be promoted to 'int'}}
  58 }
  59
  60 #if __cplusplus >= 201103L
  61 // We used to have bugs identifying the correct enclosing function scope in a
  62 // lambda.
  63
  64 void fixed_lambda_varargs_function(int a, ...) {
  65   [](int b) {
  66     __builtin_va_start(ap, b); // expected-error {{'va_start' used in function with fixed args}}
  67   }(42);
  68 }
  69 void varargs_lambda_fixed_function(int a) {
  70   [](int b, ...) {
  71     __builtin_va_start(ap, b); // correct
  72   }(42);
  73 }
  74
  75 auto fixed_lambda_global = [](int f) {
  76   __builtin_va_start(ap, f); // expected-error {{'va_start' used in function with fixed args}}
  77 };
  78 auto varargs_lambda_global = [](int f, ...) {
  79   __builtin_va_start(ap, f); // correct
  80 };
  81
  82 void record_member_init(int a, ...) {
  83   struct Foo {
  84     int a = 0;
  85     // expected-error@+1 {{'va_start' cannot be used outside a function}}
  86     int b = (__builtin_va_start(ap, a), 0);
  87   };
  88 }
  89 #endif