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// Copyright 2022 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// -----------------------------------------------------------------------------
// File: log/internal/check_op.h
// -----------------------------------------------------------------------------
//
// This file declares helpers routines and macros used to implement `CHECK`
// macros.
#ifndef ABSL_LOG_INTERNAL_CHECK_OP_H_
#define ABSL_LOG_INTERNAL_CHECK_OP_H_
#include <stdint.h>
#include <ostream>
#include <sstream>
#include <string>
#include <utility>
#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/optimization.h"
#include "absl/log/internal/nullguard.h"
#include "absl/log/internal/nullstream.h"
#include "absl/log/internal/strip.h"
// `ABSL_LOG_INTERNAL_STRIP_STRING_LITERAL` wraps string literals that
// should be stripped when `ABSL_MIN_LOG_LEVEL` exceeds `kFatal`.
#ifdef ABSL_MIN_LOG_LEVEL
#define ABSL_LOG_INTERNAL_STRIP_STRING_LITERAL(literal) \
(::absl::LogSeverity::kFatal >= \
static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL) \
? (literal) \
: "")
#else
#define ABSL_LOG_INTERNAL_STRIP_STRING_LITERAL(literal) (literal)
#endif
#ifdef NDEBUG
// `NDEBUG` is defined, so `DCHECK_EQ(x, y)` and so on do nothing. However, we
// still want the compiler to parse `x` and `y`, because we don't want to lose
// potentially useful errors and warnings.
#define ABSL_LOG_INTERNAL_DCHECK_NOP(x, y) \
while (false && ((void)(x), (void)(y), 0)) \
::absl::log_internal::NullStream().InternalStream()
#endif
#define ABSL_LOG_INTERNAL_CHECK_OP(name, op, val1, val1_text, val2, val2_text) \
while ( \
::std::string* absl_log_internal_check_op_result ABSL_ATTRIBUTE_UNUSED = \
::absl::log_internal::name##Impl( \
::absl::log_internal::GetReferenceableValue(val1), \
::absl::log_internal::GetReferenceableValue(val2), \
ABSL_LOG_INTERNAL_STRIP_STRING_LITERAL(val1_text \
" " #op " " val2_text))) \
ABSL_LOG_INTERNAL_CHECK(*absl_log_internal_check_op_result).InternalStream()
#define ABSL_LOG_INTERNAL_QCHECK_OP(name, op, val1, val1_text, val2, \
val2_text) \
while (::std::string* absl_log_internal_qcheck_op_result = \
::absl::log_internal::name##Impl( \
::absl::log_internal::GetReferenceableValue(val1), \
::absl::log_internal::GetReferenceableValue(val2), \
ABSL_LOG_INTERNAL_STRIP_STRING_LITERAL( \
val1_text " " #op " " val2_text))) \
ABSL_LOG_INTERNAL_QCHECK(*absl_log_internal_qcheck_op_result).InternalStream()
#define ABSL_LOG_INTERNAL_CHECK_STROP(func, op, expected, s1, s1_text, s2, \
s2_text) \
while (::std::string* absl_log_internal_check_strop_result = \
::absl::log_internal::Check##func##expected##Impl( \
(s1), (s2), \
ABSL_LOG_INTERNAL_STRIP_STRING_LITERAL(s1_text " " #op \
" " s2_text))) \
ABSL_LOG_INTERNAL_CHECK(*absl_log_internal_check_strop_result) \
.InternalStream()
#define ABSL_LOG_INTERNAL_QCHECK_STROP(func, op, expected, s1, s1_text, s2, \
s2_text) \
while (::std::string* absl_log_internal_qcheck_strop_result = \
::absl::log_internal::Check##func##expected##Impl( \
(s1), (s2), \
ABSL_LOG_INTERNAL_STRIP_STRING_LITERAL(s1_text " " #op \
" " s2_text))) \
ABSL_LOG_INTERNAL_QCHECK(*absl_log_internal_qcheck_strop_result) \
.InternalStream()
// This one is tricky:
// * We must evaluate `val` exactly once, yet we need to do two things with it:
// evaluate `.ok()` and (sometimes) `.ToString()`.
// * `val` might be an `absl::Status` or some `absl::StatusOr<T>`.
// * `val` might be e.g. `ATemporary().GetStatus()`, which may return a
// reference to a member of `ATemporary` that is only valid until the end of
// the full expression.
// * We don't want this file to depend on `absl::Status` `#include`s or linkage,
// nor do we want to move the definition to status and introduce a dependency
// in the other direction. We can be assured that callers must already have a
// `Status` and the necessary `#include`s and linkage.
// * Callsites should be small and fast (at least when `val.ok()`): one branch,
// minimal stack footprint.
// * In particular, the string concat stuff should be out-of-line and emitted
// in only one TU to save linker input size
// * We want the `val.ok()` check inline so static analyzers and optimizers can
// see it.
// * As usual, no braces so we can stream into the expansion with `operator<<`.
// * Also as usual, it must expand to a single (partial) statement with no
// ambiguous-else problems.
#define ABSL_LOG_INTERNAL_CHECK_OK(val, val_text) \
for (::std::pair<const ::absl::Status*, ::std::string*> \
absl_log_internal_check_ok_goo; \
absl_log_internal_check_ok_goo.first = \
::absl::log_internal::AsStatus(val), \
absl_log_internal_check_ok_goo.second = \
ABSL_PREDICT_TRUE(absl_log_internal_check_ok_goo.first->ok()) \
? nullptr \
: ::absl::status_internal::MakeCheckFailString( \
absl_log_internal_check_ok_goo.first, \
ABSL_LOG_INTERNAL_STRIP_STRING_LITERAL(val_text \
" is OK")), \
!ABSL_PREDICT_TRUE(absl_log_internal_check_ok_goo.first->ok());) \
ABSL_LOG_INTERNAL_CHECK(*absl_log_internal_check_ok_goo.second) \
.InternalStream()
#define ABSL_LOG_INTERNAL_QCHECK_OK(val, val_text) \
for (::std::pair<const ::absl::Status*, ::std::string*> \
absl_log_internal_check_ok_goo; \
absl_log_internal_check_ok_goo.first = \
::absl::log_internal::AsStatus(val), \
absl_log_internal_check_ok_goo.second = \
ABSL_PREDICT_TRUE(absl_log_internal_check_ok_goo.first->ok()) \
? nullptr \
: ::absl::status_internal::MakeCheckFailString( \
absl_log_internal_check_ok_goo.first, \
ABSL_LOG_INTERNAL_STRIP_STRING_LITERAL(val_text \
" is OK")), \
!ABSL_PREDICT_TRUE(absl_log_internal_check_ok_goo.first->ok());) \
ABSL_LOG_INTERNAL_QCHECK(*absl_log_internal_check_ok_goo.second) \
.InternalStream()
namespace absl {
ABSL_NAMESPACE_BEGIN
class Status;
template <typename T>
class StatusOr;
namespace status_internal {
std::string* MakeCheckFailString(const absl::Status* status,
const char* prefix);
} // namespace status_internal
namespace log_internal {
// Convert a Status or a StatusOr to its underlying status value.
//
// (This implementation does not require a dep on absl::Status to work.)
inline const absl::Status* AsStatus(const absl::Status& s) { return &s; }
template <typename T>
const absl::Status* AsStatus(const absl::StatusOr<T>& s) {
return &s.status();
}
// A helper class for formatting `expr (V1 vs. V2)` in a `CHECK_XX` statement.
// See `MakeCheckOpString` for sample usage.
class CheckOpMessageBuilder final {
public:
// Inserts `exprtext` and ` (` to the stream.
explicit CheckOpMessageBuilder(const char* exprtext);
~CheckOpMessageBuilder() = default;
// For inserting the first variable.
std::ostream& ForVar1() { return stream_; }
// For inserting the second variable (adds an intermediate ` vs. `).
std::ostream& ForVar2();
// Get the result (inserts the closing `)`).
std::string* NewString();
private:
std::ostringstream stream_;
};
// This formats a value for a failing `CHECK_XX` statement. Ordinarily, it uses
// the definition for `operator<<`, with a few special cases below.
template <typename T>
inline void MakeCheckOpValueString(std::ostream& os, const T& v) {
os << log_internal::NullGuard<T>::Guard(v);
}
// Overloads for char types provide readable values for unprintable characters.
void MakeCheckOpValueString(std::ostream& os, char v);
void MakeCheckOpValueString(std::ostream& os, signed char v);
void MakeCheckOpValueString(std::ostream& os, unsigned char v);
void MakeCheckOpValueString(std::ostream& os, const void* p);
namespace detect_specialization {
// MakeCheckOpString is being specialized for every T and U pair that is being
// passed to the CHECK_op macros. However, there is a lot of redundancy in these
// specializations that creates unnecessary library and binary bloat.
// The number of instantiations tends to be O(n^2) because we have two
// independent inputs. This technique works by reducing `n`.
//
// Most user-defined types being passed to CHECK_op end up being printed as a
// builtin type. For example, enums tend to be implicitly converted to its
// underlying type when calling operator<<, and pointers are printed with the
// `const void*` overload.
// To reduce the number of instantiations we coerce these values before calling
// MakeCheckOpString instead of inside it.
//
// To detect if this coercion is needed, we duplicate all the relevant
// operator<< overloads as specified in the standard, just in a different
// namespace. If the call to `stream << value` becomes ambiguous, it means that
// one of these overloads is the one selected by overload resolution. We then
// do overload resolution again just with our overload set to see which one gets
// selected. That tells us which type to coerce to.
// If the augmented call was not ambiguous, it means that none of these were
// selected and we can't coerce the input.
//
// As a secondary step to reduce code duplication, we promote integral types to
// their 64-bit variant. This does not change the printed value, but reduces the
// number of instantiations even further. Promoting an integer is very cheap at
// the call site.
int64_t operator<<(std::ostream&, short value); // NOLINT
int64_t operator<<(std::ostream&, unsigned short value); // NOLINT
int64_t operator<<(std::ostream&, int value);
int64_t operator<<(std::ostream&, unsigned int value);
int64_t operator<<(std::ostream&, long value); // NOLINT
uint64_t operator<<(std::ostream&, unsigned long value); // NOLINT
int64_t operator<<(std::ostream&, long long value); // NOLINT
uint64_t operator<<(std::ostream&, unsigned long long value); // NOLINT
float operator<<(std::ostream&, float value);
double operator<<(std::ostream&, double value);
long double operator<<(std::ostream&, long double value);
bool operator<<(std::ostream&, bool value);
const void* operator<<(std::ostream&, const void* value);
const void* operator<<(std::ostream&, std::nullptr_t);
// These `char` overloads are specified like this in the standard, so we have to
// write them exactly the same to ensure the call is ambiguous.
// If we wrote it in a different way (eg taking std::ostream instead of the
// template) then one call might have a higher rank than the other and it would
// not be ambiguous.
template <typename Traits>
char operator<<(std::basic_ostream<char, Traits>&, char);
template <typename Traits>
signed char operator<<(std::basic_ostream<char, Traits>&, signed char);
template <typename Traits>
unsigned char operator<<(std::basic_ostream<char, Traits>&, unsigned char);
template <typename Traits>
const char* operator<<(std::basic_ostream<char, Traits>&, const char*);
template <typename Traits>
const signed char* operator<<(std::basic_ostream<char, Traits>&,
const signed char*);
template <typename Traits>
const unsigned char* operator<<(std::basic_ostream<char, Traits>&,
const unsigned char*);
// This overload triggers when the call is not ambiguous.
// It means that T is being printed with some overload not on this list.
// We keep the value as `const T&`.
template <typename T, typename = decltype(std::declval<std::ostream&>()
<< std::declval<const T&>())>
const T& Detect(int);
// This overload triggers when the call is ambiguous.
// It means that T is either one from this list or printed as one from this
// list. Eg an enum that decays to `int` for printing.
// We ask the overload set to give us the type we want to convert it to.
template <typename T>
decltype(detect_specialization::operator<<(std::declval<std::ostream&>(),
std::declval<const T&>()))
Detect(char);
} // namespace detect_specialization
template <typename T>
using CheckOpStreamType = decltype(detect_specialization::Detect<T>(0));
// Build the error message string. Specify no inlining for code size.
template <typename T1, typename T2>
ABSL_ATTRIBUTE_RETURNS_NONNULL std::string* MakeCheckOpString(
T1 v1, T2 v2, const char* exprtext) ABSL_ATTRIBUTE_NOINLINE;
template <typename T1, typename T2>
std::string* MakeCheckOpString(T1 v1, T2 v2, const char* exprtext) {
CheckOpMessageBuilder comb(exprtext);
MakeCheckOpValueString(comb.ForVar1(), v1);
MakeCheckOpValueString(comb.ForVar2(), v2);
return comb.NewString();
}
// Add a few commonly used instantiations as extern to reduce size of objects
// files.
#define ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(x) \
extern template std::string* MakeCheckOpString(x, x, const char*)
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(bool);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(int64_t);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(uint64_t);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(float);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(double);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(char);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(unsigned char);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(const std::string&);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(const absl::string_view&);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(const char*);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(const signed char*);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(const unsigned char*);
ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN(const void*);
#undef ABSL_LOG_INTERNAL_DEFINE_MAKE_CHECK_OP_STRING_EXTERN
// Helper functions for `ABSL_LOG_INTERNAL_CHECK_OP` macro family. The
// `(int, int)` override works around the issue that the compiler will not
// instantiate the template version of the function on values of unnamed enum
// type.
#define ABSL_LOG_INTERNAL_CHECK_OP_IMPL(name, op) \
template <typename T1, typename T2> \
inline constexpr ::std::string* name##Impl(const T1& v1, const T2& v2, \
const char* exprtext) { \
using U1 = CheckOpStreamType<T1>; \
using U2 = CheckOpStreamType<T2>; \
return ABSL_PREDICT_TRUE(v1 op v2) \
? nullptr \
: MakeCheckOpString<U1, U2>(v1, v2, exprtext); \
} \
inline constexpr ::std::string* name##Impl(int v1, int v2, \
const char* exprtext) { \
return name##Impl<int, int>(v1, v2, exprtext); \
}
ABSL_LOG_INTERNAL_CHECK_OP_IMPL(Check_EQ, ==)
ABSL_LOG_INTERNAL_CHECK_OP_IMPL(Check_NE, !=)
ABSL_LOG_INTERNAL_CHECK_OP_IMPL(Check_LE, <=)
ABSL_LOG_INTERNAL_CHECK_OP_IMPL(Check_LT, <)
ABSL_LOG_INTERNAL_CHECK_OP_IMPL(Check_GE, >=)
ABSL_LOG_INTERNAL_CHECK_OP_IMPL(Check_GT, >)
#undef ABSL_LOG_INTERNAL_CHECK_OP_IMPL
std::string* CheckstrcmptrueImpl(const char* s1, const char* s2,
const char* exprtext);
std::string* CheckstrcmpfalseImpl(const char* s1, const char* s2,
const char* exprtext);
std::string* CheckstrcasecmptrueImpl(const char* s1, const char* s2,
const char* exprtext);
std::string* CheckstrcasecmpfalseImpl(const char* s1, const char* s2,
const char* exprtext);
// `CHECK_EQ` and friends want to pass their arguments by reference, however
// this winds up exposing lots of cases where people have defined and
// initialized static const data members but never declared them (i.e. in a .cc
// file), meaning they are not referenceable. This function avoids that problem
// for integers (the most common cases) by overloading for every primitive
// integer type, even the ones we discourage, and returning them by value.
template <typename T>
inline constexpr const T& GetReferenceableValue(const T& t) {
return t;
}
inline constexpr char GetReferenceableValue(char t) { return t; }
inline constexpr unsigned char GetReferenceableValue(unsigned char t) {
return t;
}
inline constexpr signed char GetReferenceableValue(signed char t) { return t; }
inline constexpr short GetReferenceableValue(short t) { return t; } // NOLINT
inline constexpr unsigned short GetReferenceableValue( // NOLINT
unsigned short t) { // NOLINT
return t;
}
inline constexpr int GetReferenceableValue(int t) { return t; }
inline constexpr unsigned int GetReferenceableValue(unsigned int t) {
return t;
}
inline constexpr long GetReferenceableValue(long t) { return t; } // NOLINT
inline constexpr unsigned long GetReferenceableValue( // NOLINT
unsigned long t) { // NOLINT
return t;
}
inline constexpr long long GetReferenceableValue(long long t) { // NOLINT
return t;
}
inline constexpr unsigned long long GetReferenceableValue( // NOLINT
unsigned long long t) { // NOLINT
return t;
}
} // namespace log_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_LOG_INTERNAL_CHECK_OP_H_