James Peach created MESOS-7907:
----------------------------------
Summary: `async` fails to accept mutable lambdas
Key: MESOS-7907
URL: https://issues.apache.org/jira/browse/MESOS-7907
Project: Mesos
Issue Type: Bug
Components: libprocess
Reporter: James Peach
{{process::async}} fails to compile when you pass it a mutable lambda.
For example:
{code}
diff --git a/3rdparty/libprocess/src/tests/process_tests.cpp
b/3rdparty/libprocess/src/tests/process_tests.cpp
index 8d3660070..399462fc2 100644
--- a/3rdparty/libprocess/src/tests/process_tests.cpp
+++ b/3rdparty/libprocess/src/tests/process_tests.cpp
@@ -1464,6 +1464,9 @@ TEST(ProcessTest, THREADSAFE_Async)
// Non-void function that returns a future.
EXPECT_EQ("42", async(&itoa1, &i).get().get());
+
+ int value = 99;
+ EXPECT_EQ(99, async([value] mutable { return value; }));
}
{code}
Generates this compilation error:
{noformat}
In file included from
../../../3rdparty/libprocess/src/tests/process_tests.cpp:32:0:
../../../3rdparty/libprocess/include/process/async.hpp: In instantiation of
‘typename std::result_of<F()>::type
process::AsyncExecutorProcess::execute(const F&) [with F =
ProcessTest_THREADSAFE_Async_Test::TestBody()::<lambda()>; typename
std::enable_if<(! std::is_void<typename std::result_of<F()>::type>::value),
int>::type <anonymous> = 0; typename std::result_of<F()>::type = int]’:
../../../3rdparty/libprocess/include/process/async.hpp:184:74: required from
‘process::Future<typename std::result_of<F()>::type>
process::AsyncExecutor::execute(const F&, typename std::enable_if<(!
std::is_void<typename std::result_of<F()>::type>::value)>::type*) [with F =
ProcessTest_THREADSAFE_Async_Test::TestBody()::<lambda()>; typename
std::result_of<F()>::type = int; typename std::enable_if<(!
std::is_void<typename std::result_of<F()>::type>::value)>::type = void]’
../../../3rdparty/libprocess/include/process/async.hpp:242:35: required from
‘process::Future<typename std::result_of<F()>::type> process::async(const F&,
typename std::enable_if<(! std::is_void<typename
std::result_of<F()>::type>::value)>::type*) [with F =
ProcessTest_THREADSAFE_Async_Test::TestBody()::<lambda()>; typename
std::result_of<F()>::type = int; typename std::enable_if<(!
std::is_void<typename std::result_of<F()>::type>::value)>::type = void]’
../../../3rdparty/libprocess/src/tests/process_tests.cpp:1469:3: required
from here
../../../3rdparty/libprocess/include/process/async.hpp:87:13: error: no match
for call to ‘(const ProcessTest_THREADSAFE_Async_Test::TestBody()::<lambda()>)
()’
return f();
~^~
{noformat}
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