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AK+Everywhere: Do not implicitly copy variables in TRY macros

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For example, consider cases where we want to propagate errors only in
specific instances:

    auto result = read_data(); // something like ErrorOr<ByteBuffer>
    if (result.is_error() && result.error().code() != EINTR)
        continue;
    auto bytes = TRY(result);

The TRY invocation will currently copy the byte buffer when the
expression (in this case, just a local variable) is stored into
_temporary_result.

This patch binds the expression to a reference to prevent such copies.
In less trival invocations (such as TRY(some_function()), this will
incur only temporary lifetime extensions, i.e. no functional change.
This commit is contained in:
Timothy Flynn 2023-02-09 13:27:43 -05:00 • committed by Linus Groh
parent 4a916cd379
commit 604d5f5bca
11 changed files with 15 additions and 15 deletions
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4
Userland/Libraries/LibJS/Runtime/Completion.h
View file

@ -21,7 +21,7 @@ namespace JS {
({ \
/* Ignore -Wshadow to allow nesting the macro. */ \
AK_IGNORE_DIAGNOSTIC("-Wshadow", \
auto _temporary_result = (expression)); \
auto&& _temporary_result = (expression)); \
if (_temporary_result.is_error()) { \
VERIFY(_temporary_result.error().code() == ENOMEM); \
return vm.throw_completion<JS::InternalError>(JS::ErrorType::OutOfMemory); \
@ -35,7 +35,7 @@ namespace JS {
({ \
/* Ignore -Wshadow to allow nesting the macro. */ \
AK_IGNORE_DIAGNOSTIC("-Wshadow", \
auto _temporary_result = (expression)); \
auto&& _temporary_result = (expression)); \
if (_temporary_result.is_error()) { \
auto _completion = _temporary_result.release_error(); \
\