clang/test/SemaCXX/vla-ext-diag.cpp

   1 // RUN: %clang_cc1 -verify=gnu -std=gnu++11 %s
   2 // RUN: %clang_cc1 -verify=expected,cxx11 -Wvla -std=gnu++11 %s
   3 // RUN: %clang_cc1 -verify=expected,cxx11 -std=c++11 %s
   4 // RUN: %clang_cc1 -verify=expected,cxx98 -std=c++98 %s
   5 // RUN: %clang_cc1 -verify=expected,off -std=c++11 -Wno-vla-extension-static-assert %s
   6 // gnu-no-diagnostics
   7
   8 // Demonstrate that we do not diagnose use of VLAs by default in GNU mode, but
   9 // we do diagnose them in C++ mode. Also note that we suggest use of
  10 // static_assert, but only in C++11 and later and only if the warning group is
  11 // not disabled.
  12
  13 // C++98 mode does not emit the same notes as C++11 mode because in C++98,
  14 // we're looking for an integer constant expression, whereas in C++11 and later,
  15 // we're looking for a constant expression that is of integer type (these are
  16 // different operations; ICE looks at the syntactic form of the expression, but
  17 // C++11 constant expressions require calculating the expression value).
  18 void func(int n) { // cxx11-note {{declared here}} off-note {{declared here}}
  19   int vla[n]; // expected-warning {{variable length arrays in C++ are a Clang extension}} \
  20                  cxx11-note {{function parameter 'n' with unknown value cannot be used in a constant expression}} \
  21                  off-note {{function parameter 'n' with unknown value cannot be used in a constant expression}}
  22 }
  23
  24 void old_style_static_assert(int n) { // cxx11-note 5 {{declared here}} off-note 2 {{declared here}}
  25   int array1[n != 12 ? 1 : -1]; // cxx11-warning {{variable length arrays in C++ are a Clang extension; did you mean to use 'static_assert'?}} \
  26                                    cxx98-warning {{variable length arrays in C++ are a Clang extension}} \
  27                                    cxx11-note {{function parameter 'n' with unknown value cannot be used in a constant expression}}
  28   int array2[n != 12 ? -1 : 1]; // cxx11-warning {{variable length arrays in C++ are a Clang extension; did you mean to use 'static_assert'?}} \
  29                                    cxx98-warning {{variable length arrays in C++ are a Clang extension}} \
  30                                    cxx11-note {{function parameter 'n' with unknown value cannot be used in a constant expression}}
  31   int array3[n != 12 ? 1 : n];  // expected-warning {{variable length arrays in C++ are a Clang extension}} \
  32                                    cxx11-note {{function parameter 'n' with unknown value cannot be used in a constant expression}} \
  33                                    off-note {{function parameter 'n' with unknown value cannot be used in a constant expression}}
  34   int array4[(n ? 1 : -1)];     // cxx11-warning {{variable length arrays in C++ are a Clang extension; did you mean to use 'static_assert'?}} \
  35                                    cxx98-warning {{variable length arrays in C++ are a Clang extension}} \
  36                                    cxx11-note {{function parameter 'n' with unknown value cannot be used in a constant expression}}
  37   int array5[n ? 1 : 0];        // expected-warning {{variable length arrays in C++ are a Clang extension}} \
  38                                    cxx11-note {{function parameter 'n' with unknown value cannot be used in a constant expression}} \
  39                                    off-note {{function parameter 'n' with unknown value cannot be used in a constant expression}}
  40 }