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, 5 insertions, 6 deletions

diff --git a/Source/cmFLTKWrapUICommand.cxx b/Source/cmFLTKWrapUICommand.cxx
index ccd6be9..2150051 100644
--- a/Source/cmFLTKWrapUICommand.cxx
+++ b/Source/cmFLTKWrapUICommand.cxx
@@ -21,12 +21,11 @@ static void FinalAction(cmMakefile& makefile, std::string const& name)
   // they didn;t then print a warning and add then anyhow
   cmTarget* target = makefile.FindLocalNonAliasTarget(name);
   if (!target) {
-    std::string msg =
-      "FLTK_WRAP_UI was called with a target that was never created: ";
-    msg += name;
-    msg += ".  The problem was found while processing the source directory: ";
-    msg += makefile.GetCurrentSourceDirectory();
-    msg += ".  This FLTK_WRAP_UI call will be ignored.";
+    std::string msg = cmStrCat(
+      "FLTK_WRAP_UI was called with a target that was never created: ", name,
+      ".  The problem was found while processing the source directory: ",
+      makefile.GetCurrentSourceDirectory(),
+      ".  This FLTK_WRAP_UI call will be ignored.");
     cmSystemTools::Message(msg, "Warning");
   }
 }