clang/test/Sema/alias-unused.cpp

   1 // RUN: %clang_cc1 -triple x86_64-linux -Wunused -x c -verify %s
   2 // RUN: %clang_cc1 -triple x86_64-linux -Wunused -verify=expected,cxx %s
   3
   4 #ifdef __cplusplus
   5 extern "C" {
   6 #endif
   7 static int f(void) { return 42; }
   8 int g(void) __attribute__((alias("f")));
   9
  10 static int foo [] = { 42, 0xDEAD }; // cxx-warning{{variable 'foo' is not needed and will not be emitted}}
  11 extern typeof(foo) bar __attribute__((unused, alias("foo")));
  12
  13 /// https://github.com/llvm/llvm-project/issues/88593
  14 /// We report a warning in C++ mode because the internal linkage `resolver` gets
  15 /// mangled as it does not have a language linkage. GCC does not mangle
  16 /// `resolver` or report a warning.
  17 static int (*resolver(void))(void) { return f; } // cxx-warning{{unused function 'resolver'}}
  18 int ifunc(void) __attribute__((ifunc("resolver")));
  19
  20 static int __attribute__((overloadable)) f0(int x) { return x; }
  21 static float __attribute__((overloadable)) f0(float x) { return x; } // expected-warning{{unused function 'f0'}}
  22 int g0(void) __attribute__((alias("_ZL2f0i")));
  23
  24 #ifdef __cplusplus
  25 static int f1() { return 42; }
  26 int g1(void) __attribute__((alias("_ZL2f1v")));
  27 }
  28
  29 /// We demangle alias/ifunc target and mark all found functions as used.
  30
  31 static int f2(int) { return 42; } // cxx-warning{{unused function 'f2'}}
  32 static int f2() { return 42; }
  33 int g2() __attribute__((alias("_ZL2f2v")));
  34
  35 static int (*resolver1())() { return f; } // cxx-warning{{unused function 'resolver1'}}
  36 static int (*resolver1(int))() { return f; }
  37 int ifunc1() __attribute__((ifunc("_ZL9resolver1i")));
  38
  39 /// TODO: We should report "unused function" for f3(int).
  40 namespace ns {
  41 static int f3(int) { return 42; } // cxx-warning{{unused function 'f3'}}
  42 static int f3() { return 42; } // cxx-warning{{unused function 'f3'}}
  43 int g3() __attribute__((alias("_ZN2nsL2f3Ev")));
  44 }
  45
  46 template <class T>
  47 static void *f4(T) { return nullptr; }
  48 static void *f4() { return nullptr; } // cxx-warning{{unused function 'f4'}}
  49 extern void g4_int() __attribute__((ifunc("_ZL2f4IiEPvT_")));
  50 extern void g4_char() __attribute__((ifunc("_ZL2f4IcEPcT_"))); // rejected by CodeGen
  51 void *use4 = f4(0);
  52 #endif