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Workaround MSVC __VA_ARGS__ weirdness #2514

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merged 8 commits into from
Oct 23, 2019
Merged

Workaround MSVC __VA_ARGS__ weirdness #2514

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c081cee
Workaround MSVC VA_ARGS weirdness
thejcannon Oct 11, 2019
c1e8e71
Add a compile test
thejcannon Oct 11, 2019
d935e8e
Fix preprocessor tests
thejcannon Oct 11, 2019
fe112cf
Replace compile-test with preprocessor test
thejcannon Oct 11, 2019
5fe5233
Removing extraneous test
thejcannon Oct 11, 2019
f8961b9
Evaluate and cat NARG in different macros
thejcannon Oct 11, 2019
3e81346
Removing extraneous parenthesis
thejcannon Oct 11, 2019
e1b67b0
Avoid recursive macros
thejcannon Oct 11, 2019
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101 changes: 29 additions & 72 deletions googlemock/include/gmock/internal/gmock-pp.h
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Original file line number Diff line number Diff line change
@@ -1,19 +1,6 @@
#ifndef THIRD_PARTY_GOOGLETEST_GOOGLEMOCK_INCLUDE_GMOCK_PP_H_
#define THIRD_PARTY_GOOGLETEST_GOOGLEMOCK_INCLUDE_GMOCK_PP_H_

#undef GMOCK_PP_INTERNAL_USE_MSVC
#if defined(__clang__)
#define GMOCK_PP_INTERNAL_USE_MSVC 0
#elif defined(_MSC_VER)
// TODO(iserna): Also verify tradional versus comformant preprocessor.
static_assert(
_MSC_VER >= 1900,
"MSVC version not supported. There is support for MSVC 14.0 and above.");
#define GMOCK_PP_INTERNAL_USE_MSVC 1
#else
#define GMOCK_PP_INTERNAL_USE_MSVC 0
#endif

// Expands and concatenates the arguments. Constructed macros reevaluate.
#define GMOCK_PP_CAT(_1, _2) GMOCK_PP_INTERNAL_CAT(_1, _2)

Expand All @@ -29,10 +16,6 @@ static_assert(
// Returns the only argument.
#define GMOCK_PP_IDENTITY(_1) _1

// MSVC preprocessor collapses __VA_ARGS__ in a single argument, we use a
// CAT-like directive to force correct evaluation. Each macro has its own.
#if GMOCK_PP_INTERNAL_USE_MSVC

// Evaluates to the number of arguments after expansion.
//
// #define PAIR x, y
Expand All @@ -43,45 +26,29 @@ static_assert(
// GMOCK_PP_NARG(PAIR) => 2
//
// Requires: the number of arguments after expansion is at most 15.
#define GMOCK_PP_NARG(...) \
GMOCK_PP_INTERNAL_NARG_CAT( \
GMOCK_PP_INTERNAL_INTERNAL_16TH(__VA_ARGS__, 15, 14, 13, 12, 11, 10, 9, \
8, 7, 6, 5, 4, 3, 2, 1), )
#define GMOCK_PP_NARG(...) \
GMOCK_PP_INTERNAL_16TH( \
(__VA_ARGS__, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1))

// Returns 1 if the expansion of arguments has an unprotected comma. Otherwise
// returns 0. Requires no more than 15 unprotected commas.
#define GMOCK_PP_HAS_COMMA(...) \
GMOCK_PP_INTERNAL_HAS_COMMA_CAT( \
GMOCK_PP_INTERNAL_INTERNAL_16TH(__VA_ARGS__, 1, 1, 1, 1, 1, 1, 1, 1, 1, \
1, 1, 1, 1, 1, 0), )
#define GMOCK_PP_HAS_COMMA(...) \
GMOCK_PP_INTERNAL_16TH( \
(__VA_ARGS__, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0))

// Returns the first argument.
#define GMOCK_PP_HEAD(...) \
GMOCK_PP_INTERNAL_HEAD_CAT(GMOCK_PP_INTERNAL_HEAD(__VA_ARGS__), )
GMOCK_PP_INTERNAL_HEAD((__VA_ARGS__))

// Returns the tail. A variadic list of all arguments minus the first. Requires
// at least one argument.
#define GMOCK_PP_TAIL(...) \
GMOCK_PP_INTERNAL_TAIL_CAT(GMOCK_PP_INTERNAL_TAIL(__VA_ARGS__), )
GMOCK_PP_INTERNAL_TAIL((__VA_ARGS__))

// Calls CAT(_Macro, NARG(__VA_ARGS__))(__VA_ARGS__)
#define GMOCK_PP_VARIADIC_CALL(_Macro, ...) \
GMOCK_PP_INTERNAL_VARIADIC_CALL_CAT( \
GMOCK_PP_CAT(_Macro, GMOCK_PP_NARG(__VA_ARGS__))(__VA_ARGS__), )

#else // GMOCK_PP_INTERNAL_USE_MSVC

#define GMOCK_PP_NARG(...) \
GMOCK_PP_INTERNAL_INTERNAL_16TH(__VA_ARGS__, 15, 14, 13, 12, 11, 10, 9, 8, \
7, 6, 5, 4, 3, 2, 1)
#define GMOCK_PP_HAS_COMMA(...) \
GMOCK_PP_INTERNAL_INTERNAL_16TH(__VA_ARGS__, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, \
1, 1, 1, 1, 0)
#define GMOCK_PP_HEAD(...) GMOCK_PP_INTERNAL_HEAD(__VA_ARGS__)
#define GMOCK_PP_TAIL(...) GMOCK_PP_INTERNAL_TAIL(__VA_ARGS__)
#define GMOCK_PP_VARIADIC_CALL(_Macro, ...) \
GMOCK_PP_CAT(_Macro, GMOCK_PP_NARG(__VA_ARGS__))(__VA_ARGS__)

#endif // GMOCK_PP_INTERNAL_USE_MSVC
GMOCK_PP_IDENTITY( \
GMOCK_PP_CAT(_Macro, GMOCK_PP_NARG(__VA_ARGS__))(__VA_ARGS__))

// If the arguments after expansion have no tokens, evaluates to `1`. Otherwise
// evaluates to `0`.
Expand Down Expand Up @@ -140,7 +107,7 @@ static_assert(
// Expands to 1 if the first argument starts with something in parentheses,
// otherwise to 0.
#define GMOCK_PP_IS_BEGIN_PARENS(...) \
GMOCK_PP_INTERNAL_ALTERNATE_HEAD( \
GMOCK_PP_HEAD( \
GMOCK_PP_CAT(GMOCK_PP_INTERNAL_IBP_IS_VARIADIC_R_, \
GMOCK_PP_INTERNAL_IBP_IS_VARIADIC_C __VA_ARGS__))

Expand Down Expand Up @@ -179,41 +146,31 @@ static_assert(
#define GMOCK_PP_INTENRAL_EMPTY_TUPLE (, , , , , , , , , , , , , , , )
#define GMOCK_PP_INTERNAL_CAT(_1, _2) _1##_2
#define GMOCK_PP_INTERNAL_STRINGIZE(...) #__VA_ARGS__
#define GMOCK_PP_INTERNAL_INTERNAL_16TH(_1, _2, _3, _4, _5, _6, _7, _8, _9, \
_10, _11, _12, _13, _14, _15, _16, \
...) \
_16
#define GMOCK_PP_INTERNAL_CAT_5(_1, _2, _3, _4, _5) _1##_2##_3##_4##_5
#define GMOCK_PP_INTERNAL_IS_EMPTY(_1, _2, _3, _4) \
GMOCK_PP_HAS_COMMA(GMOCK_PP_INTERNAL_CAT_5(GMOCK_PP_INTERNAL_IS_EMPTY_CASE_, \
_1, _2, _3, _4))
#define GMOCK_PP_INTERNAL_IS_EMPTY_CASE_0001 ,
#define GMOCK_PP_INTERNAL_IF_1(_Then, _Else) _Then
#define GMOCK_PP_INTERNAL_IF_0(_Then, _Else) _Else
#define GMOCK_PP_INTERNAL_HEAD(_1, ...) _1
#define GMOCK_PP_INTERNAL_TAIL(_1, ...) __VA_ARGS__

#if GMOCK_PP_INTERNAL_USE_MSVC
#define GMOCK_PP_INTERNAL_NARG_CAT(_1, _2) GMOCK_PP_INTERNAL_NARG_CAT_I(_1, _2)
#define GMOCK_PP_INTERNAL_HEAD_CAT(_1, _2) GMOCK_PP_INTERNAL_HEAD_CAT_I(_1, _2)
#define GMOCK_PP_INTERNAL_HAS_COMMA_CAT(_1, _2) \
GMOCK_PP_INTERNAL_HAS_COMMA_CAT_I(_1, _2)
#define GMOCK_PP_INTERNAL_TAIL_CAT(_1, _2) GMOCK_PP_INTERNAL_TAIL_CAT_I(_1, _2)
#define GMOCK_PP_INTERNAL_VARIADIC_CALL_CAT(_1, _2) \
GMOCK_PP_INTERNAL_VARIADIC_CALL_CAT_I(_1, _2)
#define GMOCK_PP_INTERNAL_NARG_CAT_I(_1, _2) _1##_2
#define GMOCK_PP_INTERNAL_HEAD_CAT_I(_1, _2) _1##_2
#define GMOCK_PP_INTERNAL_HAS_COMMA_CAT_I(_1, _2) _1##_2
#define GMOCK_PP_INTERNAL_TAIL_CAT_I(_1, _2) _1##_2
#define GMOCK_PP_INTERNAL_VARIADIC_CALL_CAT_I(_1, _2) _1##_2
#define GMOCK_PP_INTERNAL_ALTERNATE_HEAD(...) \
GMOCK_PP_INTERNAL_ALTERNATE_HEAD_CAT(GMOCK_PP_HEAD(__VA_ARGS__), )
#define GMOCK_PP_INTERNAL_ALTERNATE_HEAD_CAT(_1, _2) \
GMOCK_PP_INTERNAL_ALTERNATE_HEAD_CAT_I(_1, _2)
#define GMOCK_PP_INTERNAL_ALTERNATE_HEAD_CAT_I(_1, _2) _1##_2
#else // GMOCK_PP_INTERNAL_USE_MSVC
#define GMOCK_PP_INTERNAL_ALTERNATE_HEAD(...) GMOCK_PP_HEAD(__VA_ARGS__)
#endif // GMOCK_PP_INTERNAL_USE_MSVC
// Because of MSVC treating a token with a comma in it as a single token when passed
// to another macro, we need to force it to evaluate it as multiple tokens. We do that
// by using a "IDENTITY(MACRO PARENTHESIZED_ARGS)" macro.
// We define one per possible macro that relies on this behavior.
// Note "_Args" must be parenthesized.
#define GMOCK_PP_INTERNAL_INTERNAL_16TH(_1, _2, _3, _4, _5, _6, _7, _8, _9, \
_10, _11, _12, _13, _14, _15, _16, \
...) \
_16
#define GMOCK_PP_INTERNAL_16TH(_Args) \
GMOCK_PP_IDENTITY(GMOCK_PP_INTERNAL_INTERNAL_16TH _Args)
#define GMOCK_PP_INTERNAL_INTERNAL_HEAD(_1, ...) _1
#define GMOCK_PP_INTERNAL_HEAD(_Args) \
GMOCK_PP_IDENTITY(GMOCK_PP_INTERNAL_INTERNAL_HEAD _Args)
#define GMOCK_PP_INTERNAL_INTERNAL_TAIL(_1, ...) __VA_ARGS__
#define GMOCK_PP_INTERNAL_TAIL(_Args) \
GMOCK_PP_IDENTITY(GMOCK_PP_INTERNAL_INTERNAL_TAIL _Args)

#define GMOCK_PP_INTERNAL_IBP_IS_VARIADIC_C(...) 1 _
#define GMOCK_PP_INTERNAL_IBP_IS_VARIADIC_R_1 1,
Expand Down
10 changes: 10 additions & 0 deletions googlemock/test/gmock-pp_test.cc
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Original file line number Diff line number Diff line change
@@ -1,5 +1,10 @@
#include "gmock/internal/gmock-pp.h"

// Used to test MSVC treating __VA_ARGS__ with a comma in it as one value
#define GMOCK_TEST_REPLACE_comma_WITH_COMMA_I_comma ,
#define GMOCK_TEST_REPLACE_comma_WITH_COMMA(x) \
GMOCK_PP_CAT(GMOCK_TEST_REPLACE_comma_WITH_COMMA_I_, x)

// Static assertions.
namespace testing {
namespace internal {
Expand All @@ -17,6 +22,11 @@ static_assert(GMOCK_PP_NARG(x, y, z, w) == 4, "");
static_assert(!GMOCK_PP_HAS_COMMA(), "");
static_assert(GMOCK_PP_HAS_COMMA(b, ), "");
static_assert(!GMOCK_PP_HAS_COMMA((, )), "");
static_assert(
GMOCK_PP_HAS_COMMA(GMOCK_TEST_REPLACE_comma_WITH_COMMA(comma)), "");
static_assert(
GMOCK_PP_HAS_COMMA(GMOCK_TEST_REPLACE_comma_WITH_COMMA(comma(unrelated))),
"");
static_assert(!GMOCK_PP_IS_EMPTY(, ), "");
static_assert(!GMOCK_PP_IS_EMPTY(a), "");
static_assert(!GMOCK_PP_IS_EMPTY(()), "");
Expand Down