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micttyl
b5e55556be
`cstdlib` is added for `abort()` in carbon-language#1341 `unistd.h` was not removed with `exit()` in carbon-language#1175
90 lines
3.1 KiB
C++
90 lines
3.1 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#ifndef CARBON_COMMON_CHECK_INTERNAL_H_
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#define CARBON_COMMON_CHECK_INTERNAL_H_
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#include <cstdlib>
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/Signals.h"
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#include "llvm/Support/raw_ostream.h"
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namespace Carbon::Internal {
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// Wraps a stream and exiting for fatal errors. Should only be used by check.h
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// macros.
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class ExitingStream {
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public:
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// A tag type that renders as ": " in an ExitingStream, but only if it is
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// followed by additional output. Otherwise, it renders as "". Primarily used
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// when building macros around these streams.
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struct AddSeparator {};
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// Internal type used in macros to dispatch to the `operator|` overload.
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struct Helper {};
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ExitingStream() {
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// Start all messages with a stack trace. Printing this first ensures the
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// error message is the last thing written which makes it easier to find. It
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// also helps ensure we report the most useful stack trace and location
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// information.
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llvm::errs() << "Stack trace:\n";
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llvm::sys::PrintStackTrace(llvm::errs());
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}
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[[noreturn]] ~ExitingStream() {
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llvm_unreachable(
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"Exiting streams should only be constructed by check.h macros that "
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"ensure the special operator| exits the program prior to their "
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"destruction!");
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}
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// If the bool cast occurs, it's because the condition is false. This supports
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// && short-circuiting the creation of ExitingStream.
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explicit operator bool() const { return true; }
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// Forward output to llvm::errs.
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template <typename T>
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auto operator<<(const T& message) -> ExitingStream& {
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if (separator_) {
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llvm::errs() << ": ";
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separator_ = false;
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}
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llvm::errs() << message;
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return *this;
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}
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auto operator<<(AddSeparator /*add_separator*/) -> ExitingStream& {
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separator_ = true;
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return *this;
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}
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// Low-precedence binary operator overload used in check.h macros to flush the
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// output and exit the program. We do this in a binary operator rather than
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// the destructor to ensure good debug info and backtraces for errors.
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[[noreturn]] friend auto operator|(Helper /*helper*/,
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ExitingStream& /*rhs*/) {
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// Finish with a newline.
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llvm::errs() << "\n";
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// We assume LLVM's exit handling is installed, which will stack trace on
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// `std::abort()`. We print a more user friendly stack trace on
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// construction, but it is still useful to exit the program with
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// `std::abort()` for integration with debuggers and other tools. We also
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// want to do any pending cleanups. So we replicate the signal handling here
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// and unregister LLVM's handlers right before we abort.
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llvm::sys::RunInterruptHandlers();
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llvm::sys::unregisterHandlers();
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std::abort();
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}
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private:
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// Whether a separator should be printed if << is used again.
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bool separator_ = false;
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};
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} // namespace Carbon::Internal
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#endif // CARBON_COMMON_CHECK_INTERNAL_H_
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