clang/test/Modules/stddef.cpp

   1 // RUN: rm -rf %t
   2 // RUN: split-file %s %t
   3 // RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/no-lsv -I%t %t/stddef.cpp -verify
   4 // RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-local-submodule-visibility -fmodules-cache-path=%t/lsv -I%t %t/stddef.cpp -verify
   5
   6 //--- stddef.cpp
   7 #include <b.h>
   8
   9 void *pointer = NULL;
  10 size_t size = 0;
  11
  12 // When building with modules, a pcm is never re-imported, so re-including
  13 // stddef.h will not re-import _Builtin_stddef.null to restore the definition of
  14 // NULL, even though stddef.h will unconditionally include __stddef_null.h when
  15 // building with modules.
  16 #undef NULL
  17 #include <stddef.h>
  18
  19 void *anotherPointer = NULL; // expected-error{{use of undeclared identifier 'NULL'}}
  20
  21 // stddef.h needs to be a `textual` header to support clients doing things like
  22 // this.
  23 //
  24 // #define __need_NULL
  25 // #include <stddef.h>
  26 //
  27 // As a textual header designed to be included multiple times, it can't directly
  28 // declare anything, or those declarations would go into every module that
  29 // included it. e.g. if stddef.h contained all of its declarations, and modules
  30 // A and B included stddef.h, they would both have the declaration for size_t.
  31 // That breaks Swift, which uses the module name as part of the type name, i.e.
  32 // A.size_t and B.size_t are treated as completely different types in Swift and
  33 // cannot be interchanged. To fix that, stddef.h (and stdarg.h) are split out
  34 // into a separate file per __need macro that can be normal headers in explicit
  35 // submodules. That runs into yet another wrinkle though. When modules build,
  36 // declarations from previous submodules leak into subsequent ones when not
  37 // using local submodule visibility. Consider if stddef.h did the normal thing.
  38 //
  39 // #ifndef __STDDEF_H
  40 // #define __STDDEF_H
  41 // // include all of the sub-headers
  42 // #endif
  43 //
  44 // When SM builds without local submodule visibility, it will precompile a.h
  45 // first. When it gets to b.h, the __STDDEF_H declaration from precompiling a.h
  46 // will leak, and so when b.h includes stddef.h, it won't include any of its
  47 // sub-headers, and SM.B will thus not import _Builtin_stddef or make any of its
  48 // submodules visible. Precompiling b.h will be fine since it sees all of the
  49 // declarations from a.h including stddef.h, but clients that only include b.h
  50 // will not see any of the stddef.h types. stddef.h thus has to make sure to
  51 // always include the necessary sub-headers, even if they've been included
  52 // already. They all have their own header guards to allow this.
  53 // __stddef_null.h is extra special, so this test makes sure to cover NULL plus
  54 // one of the normal stddef.h types.
  55
  56 //--- module.modulemap
  57 module SM {
  58   module A {
  59     header "a.h"
  60     export *
  61   }
  62
  63   module B {
  64     header "b.h"
  65     export *
  66   }
  67 }
  68
  69 //--- a.h
  70 #include <stddef.h>
  71
  72 //--- b.h
  73 #include <stddef.h>