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AK+Everywhere: Disallow returning a reference from a fallible expression

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This will silently make a copy. Rather than masking this behavior, let's
explicitly disallow it.
This commit is contained in:
Timothy Flynn 2023-01-13 15:48:09 -05:00 committed by Tim Flynn
parent 3de75f6436
commit afc0e461e1
11 changed files with 86 additions and 54 deletions
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8
AK/Try.h
View file

@ -15,12 +15,18 @@
// on statement expressions [1]. This is known to be implemented
// by at least clang and gcc.
// [1] https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html
//
// If the static_assert below is triggered, it means you tried to return a reference
// from a fallible expression. This will not do what you want; the statement expression
// will create a copy regardless, so it is explicitly disallowed.
#define TRY(expression) \
({ \
/* Ignore -Wshadow to allow nesting the macro. */ \
AK_IGNORE_DIAGNOSTIC("-Wshadow", \
auto _temporary_result = (expression)); \
static_assert(!IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
if (_temporary_result.is_error()) [[unlikely]] \
return _temporary_result.release_error(); \
_temporary_result.release_value(); \
@ -31,6 +37,8 @@
/* Ignore -Wshadow to allow nesting the macro. */ \
AK_IGNORE_DIAGNOSTIC("-Wshadow", \
auto _temporary_result = (expression)); \
static_assert(!IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
VERIFY(!_temporary_result.is_error()); \
_temporary_result.release_value(); \
})

2
Kernel/Net/Socket.h
View file

@ -189,6 +189,8 @@ private:
auto result = (expression); \
if (result.is_error()) \
return set_so_error(result.release_error()); \
static_assert(!IsLvalueReference<decltype(result.release_value())>, \
"Do not return a reference from a fallible expression"); \
result.release_value(); \
})

2
Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateLocaleData.cpp
View file

@ -236,6 +236,8 @@ struct CLDR {
auto _temporary_result = (expression); \
if (_temporary_result.is_error()) \
return; \
static_assert(!IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
_temporary_result.release_value(); \
})

2
Userland/Libraries/LibAudio/LoaderError.h
View file

@ -71,5 +71,7 @@ struct LoaderError {
auto _temporary_result = (expression); \
if (_temporary_result.is_error()) \
return LoaderError(_temporary_result.release_error()); \
static_assert(!IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
_temporary_result.release_value(); \
})

2
Userland/Libraries/LibJS/Runtime/Completion.h
View file

@ -25,6 +25,8 @@ namespace JS {
VERIFY(_temporary_result.error().code() == ENOMEM); \
return vm.throw_completion<JS::InternalError>(JS::ErrorType::OutOfMemory); \
} \
static_assert(!IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
_temporary_result.release_value(); \
})

6
Userland/Libraries/LibJS/Runtime/PromiseCapability.h
View file

@ -53,6 +53,9 @@ private:
return (capability)->promise(); \
} \
\
static_assert(!IsLvalueReference<decltype(_temporary_try_or_reject_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
\
/* 2. Else if value is a Completion Record, set value to value.[[Value]]. */ \
_temporary_try_or_reject_result.release_value(); \
})
@ -76,6 +79,9 @@ private:
return Value { (capability)->promise() }; \
} \
\
static_assert(!IsLvalueReference<decltype(_temporary_try_or_reject_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
\
/* 2. Else if value is a Completion Record, set value to value.[[Value]]. */ \
_temporary_try_or_reject_result.release_value(); \
})

2
Userland/Libraries/LibVideo/DecoderError.h
View file

@ -85,6 +85,8 @@ private:
return DecoderError::from_source_location( \
((category)), _error_string, SourceLocation::current()); \
} \
static_assert(!IsLvalueReference<decltype(_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
_result.release_value(); \
})

2
Userland/Libraries/LibVideo/PlaybackManager.cpp
View file

@ -273,6 +273,8 @@ bool PlaybackManager::decode_and_queue_one_sample()
m_present_timer->start(0); \
return false; \
} \
static_assert(!IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
_temporary_result.release_value(); \
})

2
Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
View file

@ -47,6 +47,8 @@ namespace Web::Fetch::Fetching {
auto _temporary_result = (expression); \
if (_temporary_result.is_error()) \
return; \
static_assert(!IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
_temporary_result.release_value(); \
})

2
Userland/Libraries/LibWeb/WebDriver/ExecuteScript.cpp
View file

@ -36,6 +36,8 @@ namespace Web::WebDriver {
auto _temporary_result = (expression); \
if (_temporary_result.is_error()) [[unlikely]] \
return ExecuteScriptResultType::JavaScriptError; \
static_assert(!IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
_temporary_result.release_value(); \
})

2
Userland/Utilities/matroska.cpp
View file

@ -17,6 +17,8 @@
outln("Encountered a parsing error: {}", _temporary_result.error().string_literal()); \
return Error::from_string_literal("Failed to parse :("); \
} \
static_assert(!IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
_temporary_result.release_value(); \
})