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, 3 insertions, 2 deletions

diff --git a/Source/cmConfigureFileCommand.cxx b/Source/cmConfigureFileCommand.cxx
index 701214e..7e37f32 100644
--- a/Source/cmConfigureFileCommand.cxx
+++ b/Source/cmConfigureFileCommand.cxx
@@ -8,6 +8,7 @@
 #include "cmMakefile.h"
 #include "cmMessageType.h"
 #include "cmNewLineStyle.h"
+#include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
 // cmConfigureFileCommand
@@ -88,8 +89,8 @@ bool cmConfigureFileCommand(std::vector<std::string> const& args,
     }
   }
   if (!unknown_args.empty()) {
-    std::string msg = "configure_file called with unknown argument(s):\n";
-    msg += unknown_args;
+    std::string msg = cmStrCat(
+      "configure_file called with unknown argument(s):\n", unknown_args);
     status.GetMakefile().IssueMessage(MessageType::AUTHOR_WARNING, msg);
   }