Menu
It appears that MSVC treats all lambdas as noexcept. This code compiles in msvc 19.28 (checked in Compiler Explorer), but expectedly fails the static assertion in gcc:
void foo() {
auto lambda_may_throw = [] {};
static_assert(noexcept(lambda_may_throw()));
}
What is interesting is that I googled a bit but was unable to find any info on this issue. Is this really an msvc bug or just me failing to understand something?
470
You can use the noexcept exception specification to indicate that the lambda expression does not throw any exceptions. As with ordinary functions, the Microsoft C++ compiler generates warning C4297 if a lambda expression declares the noexcept exception specification and the lambda body throws an exception, as shown here:
The noexcept operator does not evaluate expression . The result is true if the set of potential exceptions of the expression is empty (until C++17)expression is non-throwing (since C++17), and false otherwise.
The noexcept operator performs a compile-time check that returns true if an expression is declared to not throw any exceptions. It can be used within a function template's noexcept specifier to declare that the function will throw exceptions for some types but not others.
Mark a function as noexcept only if all the functions that it calls, either directly or indirectly, are also noexcept or const. The compiler doesn't necessarily check every code path for exceptions that might bubble up to a noexcept function.
The behavior is only observed with /permissive.
When compiling with /permissive-, the assert triggers.
So perhaps it is a compatibility extension to support older Visual Studio code.
(You also may observe that it fails with /std:c++latest and compiles with /std:c++17 without specifying /permissive-. This is not the difference in standards, rather /std:c++latest also implies /permissive- by default)
156
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
