template | 一个简单的前端模板引擎

Without a declaration of field, this isn’t even valid syntax: the < can’t begin a template argument list, and expressions aren’t allowed there in a member-declaration. (With a suitable declaration, it could be an invalid declaration with two types and no variables.) Definitely diagnosable, and definitely a Clang bug.

You can access the command line arguments from anywhere in your code using the Environment class.

In particular, you can use Environment.GetCommandLineArgs:

You can try to locate the installed version by running:

Because it would ruin constraint normalization and subsumption rules.

As it stands now, every concept has exactly and only one definition. As such, the relationships between concepts are known and fixed. Consider the following:

A deployment is a higher abstraction that manages one or more replicasets to provide controlled rollout of a new version.

As long as you don't have a rollout in progress a deployment will result in a single replicaset with the replication factor managed by the deployment.

[temp.names]/5 says that a name prefixed by template must be a template-id, meaning that it must have a template argument list. (Or it can refer to a class/alias template without template argument list, but this is deprecated in the current draft as a result of P1787R6 authored by @DavisHerring.)

There is even an example almost identical to yours under it, identifying your use of template as ill-formed.

The requirement and example comes from CWG defect report 96, in which the possible ambiguity without the requirement is considered.

Open GCC bug report for this is here. I was not able to find a Clang bug report, but searching for it isn't that easy. Its implementation status page for defect reports however does list the defect report as unimplemented.

The value category of init + *first doesn't matter.

init in init + *first is a lvalue.

So if init + *first calls an operator+ overload taking the parameter by-value, it will cause a copy construction of that parameter

But the value of init is not required anymore after init + *first, so it makes sense to move it into the parameter instead.

Similarly a operator+ overload taking its first argument by rvalue-reference might be used to allow modification of the argument by the operation.

This is what std::move achieves here.

The standard specifies this behavior since C++20.

The type of a template parameter in a function can't be deduced from a default argument. As shown in the example on cppreference.com:

Type template parameter cannot be deduced from the type of a function default argument:

The question is not why this fails for int[], but why it works for all the other types! Unfortunately, you have fallen prey to ADL which is actually calling std::size instead of the size function you have written. This is because all overloads of your function fail, and so it looks in the namespace of the first argument for a matching function, where it finds std::size. Rerun your program with the function renamed to something else: