llvm-capstone/clang/test/SemaCXX/warn-unsafe-buffer-usage-pragma-misuse.cpp
Artem Dergachev b7bdf1996f [-Wunsafe-buffer-usage] Hide fixits/suggestions behind an extra flag.
This patch implements a new clang driver flag -fsafe-buffer-usage-suggestions
which allows turning the smart suggestion machine on and off (defaults to off).
This is valuable for stability reasons, as the machine is being rapidly improved\
and we don't want accidental breakages to ruin the build for innocent users.
It is also arguably useful in general because it enables separation of concerns
between project contributors: some users will actively update the code to
conform to the programming model, while others simply want to make sure that
they aren't regressing it. Finally, there could be other valid reasons to
opt out of suggestions entirely on some codebases (while continuing to enforce
-Wunsafe-buffer-usage warnings), such as lack of access to hardened libc++
(or even to the C++ standard library in general) on the target platform.

When the flag is disabled, the unsafe buffer usage analysis is reduced to
an extremely minimal mode of operation that contains virtually no smarts:
not only it doesn't offer automatic fixits, but also textual suggestions
such as "change the type of this variable to std::span to preserve bounds
information" are not displayed, and in fact the machine doesn't even try
to blame specific variables in the first place, it simply warns on
the operations and leaves everything else to the user. So this flag turns off
a lot more of our complex machinery than what we already turn off in presence
of say -fno-diagnostic-fixit-info.

The flag is discoverable: when it's off, the warnings are accompanied by a note:
telling the user that there's a flag they can use.

Differential Revision: https://reviews.llvm.org/D146669
2023-05-18 17:20:27 -07:00

35 lines
1.1 KiB
C++

// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage \
// RUN: -fsafe-buffer-usage-suggestions -verify %s
void beginUnclosed(int * x) {
#pragma clang unsafe_buffer_usage begin
#pragma clang unsafe_buffer_usage begin // expected-error{{already inside '#pragma unsafe_buffer_usage'}}
x++;
#pragma clang unsafe_buffer_usage end
}
void endUnopened(int *x) {
#pragma clang unsafe_buffer_usage end // expected-error{{not currently inside '#pragma unsafe_buffer_usage'}}
#pragma clang unsafe_buffer_usage begin
x++;
#pragma clang unsafe_buffer_usage end
}
void wrongOption() {
#pragma clang unsafe_buffer_usage start // expected-error{{Expected 'begin' or 'end'}}
#pragma clang unsafe_buffer_usage close // expected-error{{Expected 'begin' or 'end'}}
}
void unclosed(int * p1) {
#pragma clang unsafe_buffer_usage begin
// End of the included file will not raise the unclosed region warning:
#define _INCLUDE_NO_WARN
#include "warn-unsafe-buffer-usage-pragma.h"
#pragma clang unsafe_buffer_usage end
// End of this file raises the warning:
#pragma clang unsafe_buffer_usage begin // expected-error{{'#pragma unsafe_buffer_usage' was not ended}}
}