[PATCH] D52136: [clang-tidy] Add modernize-concat-nested-namespaces check

[Wojtek Gumuła via Phabricator via cfe-commits]

wgml marked 6 inline comments as done.
wgml added inline comments.


================
Comment at: clang-tidy/modernize/ConcatNestedNamespacesCheck.cpp:52
+    const NamespaceContextVec &Namespaces) {
+  std::ostringstream Result;
+  bool First = true;
----------------
aaron.ballman wrote:
> wgml wrote:
> > aaron.ballman wrote:
> > > Can this be rewritten with `llvm::for_each()` and a `Twine` so that we don't have to use `ostringstream` (which is a big hammer for this).
> > The main advantage of `stringstream` was that it is concise.
> > 
> > I don't think I can effectively use `Twine` to build a result in a loop. If I'm wrong, correct me, please.
> > 
> > I reworked `concatNamespaces` to use `SmallString` with another educated guess of `40` for capacity.
> The `Twine` idea I was thinking of is not too far off from what you have with `SmallString`, but perhaps is too clever:
> ```
> return std::accumulate(Namespaces.begin(), Namespaces.end(), llvm::Twine(), [](llvm::Twine Ret, const NamespaceDecl *ND) {
>   return Ret + "::" + ND->getName();
> }).str();
> ```
Yeah, I tried that, but Twine has it's `operator=` deleted.


================
Comment at: clang-tidy/modernize/ConcatNestedNamespacesCheck.cpp:31
+static bool singleNamedNamespaceChild(const NamespaceDecl &ND) {
+  const NamespaceDecl::decl_range Decls = ND.decls();
+  if (std::distance(Decls.begin(), Decls.end()) != 1)
----------------
aaron.ballman wrote:
> We usually only const-qualify local declarations when they're pointers/references, so you can drop the `const` here (and in several other places). It's not a hard and fast rule, but the clutter is not useful in such small functions.
>From my perspective, `const` is a easy way of declaring that my intention is only to name given declaration only for reading and to improve code readability. 


================
Comment at: clang-tidy/modernize/ConcatNestedNamespacesCheck.cpp:50
+
+auto ConcatNestedNamespacesCheck::concatNamespaces() -> NamespaceString {
+  NamespaceString Result("namespace ");
----------------
aaron.ballman wrote:
> I'm not keen on the trailing return type used here. It's reasonable, but clever in ways we don't use elsewhere.
Ok. Wanted to avoid line break and the...

```
ConcatNestedNamespacesCheck::NamespaceString
ConcatNestedNamespacesCheck::concatNamespaces() {...}
```

but I'll adjust.


https://reviews.llvm.org/D52136