[clang] Revert "Remove __VERSION__"

[saugustine]

Summary

This reverts commit 632a36bfcfc8273c1861f04ff6758d863c47c784.

Some targets such as Python 2.7.16 still use VERSION in
their builds. Without VERSION defined, the source code
has syntax errors.

[sylvestre.ledru]

I went ahead and committed your revert in r365992. Thanks!

Next time, please remove the clang/ from your patch
arc could not apply it:

Committing 'D64687: [clang] Revert "Remove __VERSION__"'...
Revision includes changes to paths that do not exist:

    clang/docs/LanguageExtensions.rst

[MaskRay]

In D64687#1584337, @sylvestre.ledru wrote:

I went ahead and committed your revert in r365992. Thanks!

Next time, please remove the clang/ from your patch
arc could not apply it:

I think clang/ is there just because the patch was created from the llvm-project repository (mono-repo), not the clang repository (multi-repo)

clang/docs/LanguageExtensions.rst

 option for a warning and returns true if that is a valid warning option.
 
 .. code-block:: c++
 
   #if __has_warning("-Wformat")
   ...
   #endif
 
-.. _languageextensions-builtin-macros:
-
 Builtin Macros
 ==============
 
 ``__BASE_FILE__``
   Defined to a string that contains the name of the main input file passed to
   Clang.
 
 ``__FILE_NAME__``

clang/docs/ReleaseNotes.rst

 Improvements to Clang's diagnostics
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 - ...
 
 Non-comprehensive list of changes in this release
 -------------------------------------------------
 
-- The ``__VERSION__`` macro has been removed.
-  Previously this macro was set to a string aiming to achieve compatibility with 
-  GCC 4.2.1, but that should no longer be necessary. To get Clang's version,
-  use the :ref:`clang namespaced version macros <languageextensions-builtin-macros>`.
-
 - ...
 
 
 New Compiler Flags
 ------------------
 
 - ...
 
 Deprecated Compiler Flags
 -------------------------
 
 The following options are deprecated and ignored. They will be removed in
 future versions of Clang.
 
 - ...
 
 Modified Compiler Flags
 -----------------------
 
 - ``clang -dumpversion`` now returns the version of Clang itself.
 
 - ...
 
-Removed Compiler Options
-------------------------
-
-- ...
-
 New Pragmas in Clang
 --------------------
 
 - ...
 
 Attribute Changes in Clang
 --------------------------
 

clang/lib/Basic/Version.cpp

 #ifdef CLANG_VENDOR
   OS << " (based on " << BACKEND_PACKAGE_STRING << ")";
 #endif
 
   return OS.str();
 }
 
 std::string getClangFullCPPVersion() {
+  // The version string we report in __VERSION__ is just a compacted version of
+  // the one we report on the command line.
   std::string buf;
   llvm::raw_string_ostream OS(buf);
 #ifdef CLANG_VENDOR
   OS << CLANG_VENDOR;
 #endif
   OS << "Clang " CLANG_VERSION_STRING " " << getClangFullRepositoryVersion();
   return OS.str();
 }
 
 } // end namespace clang

clang/lib/Frontend/InitPreprocessor.cpp

#undef TOSTR2
   Builder.defineMacro("__OPENCL_MEMORY_SCOPE_WORK_GROUP", "1");
   Builder.defineMacro("__OPENCL_MEMORY_SCOPE_DEVICE", "2");
   Builder.defineMacro("__OPENCL_MEMORY_SCOPE_ALL_SVM_DEVICES", "3");
   Builder.defineMacro("__OPENCL_MEMORY_SCOPE_SUB_GROUP", "4");
 
   // Support for #pragma redefine_extname (Sun compatibility)
   Builder.defineMacro("__PRAGMA_REDEFINE_EXTNAME", "1");
 
+  // As sad as it is, enough software depends on the __VERSION__ for version
+  // checks that it is necessary to report 4.2.1 (the base GCC version we claim
+  // compatibility with) first.
+  Builder.defineMacro("__VERSION__", "\"4.2.1 Compatible " +
+                      Twine(getClangFullCPPVersion()) + "\"");
+
   // Initialize language-specific preprocessor defines.
 
   // Standard conforming mode?
   if (!LangOpts.GNUMode && !LangOpts.MSVCCompat)
     Builder.defineMacro("__STRICT_ANSI__");
 
   if (!LangOpts.MSVCCompat && LangOpts.CPlusPlus11)
     Builder.defineMacro("__GXX_EXPERIMENTAL_CXX0X__");

clang/test/Index/complete-exprs.c

 typedef int type;
 void f5(float f) {
   (type)f;
 }
 
 // RUN: c-index-test -code-completion-at=%s:7:10 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:7:10 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 // CHECK-CC1: NotImplemented:{TypedText __PRETTY_FUNCTION__} (65)
+// CHECK-CC1: macro definition:{TypedText __VERSION__} (70)
 // CHECK-CC1: FunctionDecl:{ResultType int}{TypedText f}{LeftParen (}{Placeholder int}{RightParen )} (12) (unavailable)
 // CHECK-CC1-NOT: NotImplemented:{TypedText float} (65)
 // CHECK-CC1: ParmDecl:{ResultType int}{TypedText j} (8)
 // CHECK-CC1: NotImplemented:{ResultType size_t}{TypedText sizeof}{LeftParen (}{Placeholder expression-or-type}{RightParen )} (40)
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:7:10 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 // RUN: c-index-test -code-completion-at=%s:7:14 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:7:14 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 
 // RUN: c-index-test -code-completion-at=%s:7:18 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 // RUN: c-index-test -code-completion-at=%s:7:22 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 // RUN: c-index-test -code-completion-at=%s:7:2 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC2 %s
+// CHECK-CC2: macro definition:{TypedText __VERSION__} (70)
 // CHECK-CC2: FunctionDecl:{ResultType int}{TypedText f}{LeftParen (}{Placeholder int}{RightParen )} (50)
 // CHECK-CC2: NotImplemented:{TypedText float} (50)
 // CHECK-CC2: ParmDecl:{ResultType int}{TypedText j} (34)
 // CHECK-CC2: NotImplemented:{ResultType size_t}{TypedText sizeof}{LeftParen (}{Placeholder expression-or-type}{RightParen )} (40)
 // RUN: c-index-test -code-completion-at=%s:11:16 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC4 %s
 // CHECK-CC4: FunctionDecl:{ResultType int}{TypedText f}{LeftParen (}{Placeholder int}{RightParen )} (50)
 // CHECK-CC4: VarDecl:{ResultType struct X}{TypedText f1} (50) (deprecated)
 

clang/test/Preprocessor/init.c

 // COMMON:#define __GNUC_STDC_INLINE__ 1
 // COMMON:#define __GNUC__ {{.*}}
 // COMMON:#define __GXX_ABI_VERSION {{.*}}
 // COMMON:#define __ORDER_BIG_ENDIAN__ 4321
 // COMMON:#define __ORDER_LITTLE_ENDIAN__ 1234
 // COMMON:#define __ORDER_PDP_ENDIAN__ 3412
 // COMMON:#define __STDC_HOSTED__ 1
 // COMMON:#define __STDC__ 1
+// COMMON:#define __VERSION__ {{.*}}
 // COMMON:#define __clang__ 1
 // COMMON:#define __clang_major__ {{[0-9]+}}
 // COMMON:#define __clang_minor__ {{[0-9]+}}
 // COMMON:#define __clang_patchlevel__ {{[0-9]+}}
 // COMMON:#define __clang_version__ {{.*}}
 // COMMON:#define __llvm__ 1
 //
 // RUN: %clang_cc1 -E -dM -triple=x86_64-pc-win32 < /dev/null | FileCheck -match-full-lines -check-prefix C-DEFAULT %s

 // SPARC:#define __UINT_LEAST16_TYPE__ unsigned short
 // SPARC:#define __UINT_LEAST32_MAX__ 4294967295U
 // SPARC:#define __UINT_LEAST32_TYPE__ unsigned int
 // SPARC:#define __UINT_LEAST64_MAX__ 18446744073709551615ULL
 // SPARC:#define __UINT_LEAST64_TYPE__ long long unsigned int
 // SPARC:#define __UINT_LEAST8_MAX__ 255
 // SPARC:#define __UINT_LEAST8_TYPE__ unsigned char
 // SPARC:#define __USER_LABEL_PREFIX__
+// SPARC:#define __VERSION__ "4.2.1 Compatible{{.*}}
 // SPARC:#define __WCHAR_MAX__ 2147483647
 // SPARC:#define __WCHAR_TYPE__ int
 // SPARC:#define __WCHAR_WIDTH__ 32
 // SPARC:#define __WINT_TYPE__ int
 // SPARC:#define __WINT_WIDTH__ 32
 // SPARC:#define __sparc 1
 // SPARC:#define __sparc__ 1
 // SPARC:#define __sparcv8 1

 // X86_64-CLOUDABI:#define __UINT_LEAST64_TYPE__ long unsigned int
 // X86_64-CLOUDABI:#define __UINT_LEAST8_FMTX__ "hhX"
 // X86_64-CLOUDABI:#define __UINT_LEAST8_FMTo__ "hho"
 // X86_64-CLOUDABI:#define __UINT_LEAST8_FMTu__ "hhu"
 // X86_64-CLOUDABI:#define __UINT_LEAST8_FMTx__ "hhx"
 // X86_64-CLOUDABI:#define __UINT_LEAST8_MAX__ 255
 // X86_64-CLOUDABI:#define __UINT_LEAST8_TYPE__ unsigned char
 // X86_64-CLOUDABI:#define __USER_LABEL_PREFIX__
+// X86_64-CLOUDABI:#define __VERSION__ "4.2.1 Compatible{{.*}}
 // X86_64-CLOUDABI:#define __WCHAR_MAX__ 2147483647
 // X86_64-CLOUDABI:#define __WCHAR_TYPE__ int
 // X86_64-CLOUDABI:#define __WCHAR_WIDTH__ 32
 // X86_64-CLOUDABI:#define __WINT_MAX__ 2147483647
 // X86_64-CLOUDABI:#define __WINT_TYPE__ int
 // X86_64-CLOUDABI:#define __WINT_WIDTH__ 32
 // X86_64-CLOUDABI:#define __amd64 1
 // X86_64-CLOUDABI:#define __amd64__ 1

 // WEBASSEMBLY-NEXT:#define __UINT_LEAST64_TYPE__ long long unsigned int
 // WEBASSEMBLY-NEXT:#define __UINT_LEAST8_FMTX__ "hhX"
 // WEBASSEMBLY-NEXT:#define __UINT_LEAST8_FMTo__ "hho"
 // WEBASSEMBLY-NEXT:#define __UINT_LEAST8_FMTu__ "hhu"
 // WEBASSEMBLY-NEXT:#define __UINT_LEAST8_FMTx__ "hhx"
 // WEBASSEMBLY-NEXT:#define __UINT_LEAST8_MAX__ 255
 // WEBASSEMBLY-NEXT:#define __UINT_LEAST8_TYPE__ unsigned char
 // WEBASSEMBLY-NEXT:#define __USER_LABEL_PREFIX__
+// WEBASSEMBLY-NEXT:#define __VERSION__ "{{.*}}"
 // WEBASSEMBLY-NEXT:#define __WCHAR_MAX__ 2147483647
 // WEBASSEMBLY-NEXT:#define __WCHAR_TYPE__ int
 // WEBASSEMBLY-NOT:#define __WCHAR_UNSIGNED__
 // WEBASSEMBLY-NEXT:#define __WCHAR_WIDTH__ 32
 // WEBASSEMBLY-NEXT:#define __WINT_MAX__ 2147483647
 // WEBASSEMBLY-NEXT:#define __WINT_TYPE__ int
 // WEBASSEMBLY-NOT:#define __WINT_UNSIGNED__
 // WEBASSEMBLY-NEXT:#define __WINT_WIDTH__ 32

clang/utils/builtin-defines.c

 /* Undefine things we don't expect to match. */
 #undef __DEC_EVAL_METHOD__
 #undef __INT16_TYPE__
 #undef __INT32_TYPE__
 #undef __INT64_TYPE__
 #undef __INT8_TYPE__
 #undef __SSP__
 #undef __APPLE_CC__
+#undef __VERSION__
 #undef __clang__
 #undef __llvm__
 #undef __nocona
 #undef __nocona__
 #undef __k8
 #undef __k8__
 #undef __tune_nocona__
 #undef __tune_core2__