jpayne@69: // Copyright (c) 2021 Cloudflare, Inc. and contributors
jpayne@69: // Licensed under the MIT License:
jpayne@69: //
jpayne@69: // Permission is hereby granted, free of charge, to any person obtaining a copy
jpayne@69: // of this software and associated documentation files (the "Software"), to deal
jpayne@69: // in the Software without restriction, including without limitation the rights
jpayne@69: // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
jpayne@69: // copies of the Software, and to permit persons to whom the Software is
jpayne@69: // furnished to do so, subject to the following conditions:
jpayne@69: //
jpayne@69: // The above copyright notice and this permission notice shall be included in
jpayne@69: // all copies or substantial portions of the Software.
jpayne@69: //
jpayne@69: // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
jpayne@69: // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
jpayne@69: // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
jpayne@69: // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
jpayne@69: // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
jpayne@69: // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
jpayne@69: // THE SOFTWARE.
jpayne@69: 
jpayne@69: #pragma once
jpayne@69: 
jpayne@69: #include "string.h"
jpayne@69: 
jpayne@69: KJ_BEGIN_HEADER
jpayne@69: 
jpayne@69: // GCC does not implement __builtin_COLUMN() as that's non-standard but MSVC & clang do.
jpayne@69: // MSVC does as of version https://github.com/microsoft/STL/issues/54) but there's currently not any
jpayne@69: // pressing need for this for MSVC & writing the write compiler version check is annoying.
jpayne@69: // Checking for clang version is problematic due to the way that XCode lies about __clang_major__.
jpayne@69: // Instead we use __has_builtin as the feature check to check clang.
jpayne@69: // Context: https://github.com/capnproto/capnproto/issues/1305
jpayne@69: #ifdef __has_builtin
jpayne@69: #if __has_builtin(__builtin_COLUMN)
jpayne@69: #define KJ_CALLER_COLUMN() __builtin_COLUMN()
jpayne@69: #else
jpayne@69: #define KJ_CALLER_COLUMN() 0
jpayne@69: #endif
jpayne@69: #else
jpayne@69: #define KJ_CALLER_COLUMN() 0
jpayne@69: #endif
jpayne@69: 
jpayne@69: #if KJ_CPP_STD > 201703L
jpayne@69: #define KJ_COMPILER_SUPPORTS_SOURCE_LOCATION 1
jpayne@69: #elif defined(__has_builtin)
jpayne@69: // Clang 9 added these builtins: https://releases.llvm.org/9.0.0/tools/clang/docs/LanguageExtensions.html
jpayne@69: // Use __has_builtin as the way to detect this because __clang_major__ is unreliable (see above
jpayne@69: // about issue with Xcode-provided clang).
jpayne@69: #define KJ_COMPILER_SUPPORTS_SOURCE_LOCATION (   \
jpayne@69:   __has_builtin(__builtin_FILE) &&               \
jpayne@69:   __has_builtin(__builtin_LINE) &&               \
jpayne@69:   __has_builtin(__builtin_FUNCTION)              \
jpayne@69:   )
jpayne@69: #elif __GNUC__ >= 5
jpayne@69: // GCC 5 supports the required builtins: https://gcc.gnu.org/onlinedocs/gcc-5.1.0/gcc/Other-Builtins.html
jpayne@69: #define KJ_COMPILER_SUPPORTS_SOURCE_LOCATION 1
jpayne@69: #endif
jpayne@69: 
jpayne@69: namespace kj {
jpayne@69: class SourceLocation {
jpayne@69:   // libc++ doesn't seem to implement <source_location> (or even <experimental/source_location>), so
jpayne@69:   // this is a non-STL wrapper over the compiler primitives (these are the same across MSVC/clang/
jpayne@69:   // gcc). Additionally this uses kj::StringPtr for holding the strings instead of const char* which
jpayne@69:   // makes it integrate a little more nicely into KJ.
jpayne@69: 
jpayne@69:   struct Badge { explicit constexpr Badge() = default; };
jpayne@69:   // Neat little trick to make sure we can never call SourceLocation with explicit arguments.
jpayne@69: public:
jpayne@69: #if !KJ_COMPILER_SUPPORTS_SOURCE_LOCATION
jpayne@69:   constexpr SourceLocation() : fileName("??"), function("??"), lineNumber(0), columnNumber(0) {}
jpayne@69:   // Constructs a dummy source location that's not pointing at anything.
jpayne@69: #else
jpayne@69:   constexpr SourceLocation(Badge = Badge{}, const char* file = __builtin_FILE(),
jpayne@69:       const char* func = __builtin_FUNCTION(), uint line = __builtin_LINE(),
jpayne@69:       uint column = KJ_CALLER_COLUMN())
jpayne@69:     : fileName(file), function(func), lineNumber(line), columnNumber(column)
jpayne@69:   {}
jpayne@69: #endif
jpayne@69: 
jpayne@69: #if KJ_COMPILER_SUPPORTS_SOURCE_LOCATION
jpayne@69:   // This can only be exposed if we actually generate valid SourceLocation objects as otherwise all
jpayne@69:   // SourceLocation objects would confusingly (and likely problematically) be equated equal.
jpayne@69:   constexpr bool operator==(const SourceLocation& o) const {
jpayne@69:     // Pointer equality is fine here based on how SourceLocation operates & how compilers will
jpayne@69:     // intern all duplicate string constants.
jpayne@69:     return fileName == o.fileName && function == o.function && lineNumber == o.lineNumber &&
jpayne@69:         columnNumber == o.columnNumber;
jpayne@69:   }
jpayne@69: #endif
jpayne@69: 
jpayne@69:   const char* fileName;
jpayne@69:   const char* function;
jpayne@69:   uint lineNumber;
jpayne@69:   uint columnNumber;
jpayne@69: };
jpayne@69: 
jpayne@69: kj::String KJ_STRINGIFY(const SourceLocation& l);
jpayne@69: 
jpayne@69: class NoopSourceLocation {
jpayne@69:   // This is used in places where we want to conditionally compile out tracking the source location.
jpayne@69:   // As such it intentionally lacks all the features but the default constructor so that the API
jpayne@69:   // isn't accidentally used in the wrong compilation context.
jpayne@69: };
jpayne@69: 
jpayne@69: KJ_UNUSED static kj::String KJ_STRINGIFY(const NoopSourceLocation& l) {
jpayne@69:   return kj::String();
jpayne@69: }
jpayne@69: }  // namespace kj
jpayne@69: 
jpayne@69: KJ_END_HEADER