Source sweep: Use cmStrCat for string concatenation

This patch is generated by a python script that uses regular expressions to
search for string concatenation patterns of the kind

```
std::string str = <ARG0>;
str += <ARG1>;
str += <ARG2>;
...
```

and replaces them with a single `cmStrCat` call

```
std::string str = cmStrCat(<ARG0>, <ARG1>, <ARG2>, ...);
```

If any `<ARGX>` is itself a concatenated string of the kind

```
a + b + c + ...;
```

then `<ARGX>` is split into multiple arguments for the `cmStrCat` call.

If there's a sequence of literals in the `<ARGX>`, then all literals in the
sequence are concatenated and merged into a single literal argument for
the `cmStrCat` call.

Single character strings are converted to single char arguments for
the `cmStrCat` call.

`std::to_string(...)` wrappings are removed from `cmStrCat` arguments,
because it supports numeric types as well as string types.

`arg.substr(x)` arguments to `cmStrCat` are replaced with
`cm::string_view(arg).substr(x)`

1 files changed, 2 insertions, 6 deletions

diff --git a/Source/cmAuxSourceDirectoryCommand.cxx b/Source/cmAuxSourceDirectoryCommand.cxx
index 83199b4fb6..7bf19d0cf6 100644
--- a/Source/cmAuxSourceDirectoryCommand.cxx
+++ b/Source/cmAuxSourceDirectoryCommand.cxx
@@ -27,9 +27,7 @@ bool cmAuxSourceDirectoryCommand(std::vector<std::string> const& args,
   std::string const& templateDirectory = args[0];
   std::string tdir;
   if (!cmSystemTools::FileIsFullPath(templateDirectory)) {
-    tdir = mf.GetCurrentSourceDirectory();
-    tdir += "/";
-    tdir += templateDirectory;
+    tdir = cmStrCat(mf.GetCurrentSourceDirectory(), '/', templateDirectory);
   } else {
     tdir = templateDirectory;
   }
@@ -56,9 +54,7 @@ bool cmAuxSourceDirectoryCommand(std::vector<std::string> const& args,
         // Process only source files
         auto cm = mf.GetCMakeInstance();
         if (!base.empty() && cm->IsSourceExtension(ext)) {
-          std::string fullname = templateDirectory;
-          fullname += "/";
-          fullname += file;
+          std::string fullname = cmStrCat(templateDirectory, '/', file);
           // add the file as a class file so
           // depends can be done
           cmSourceFile* sf = mf.GetOrCreateSource(fullname);