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/cmExternalMakefileProjectGenerator.cxx b/Source/cmExternalMakefileProjectGenerator.cxx
index ac548112a9..83a0ba6536 100644
--- a/Source/cmExternalMakefileProjectGenerator.cxx
+++ b/Source/cmExternalMakefileProjectGenerator.cxx
@@ -2,6 +2,8 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmExternalMakefileProjectGenerator.h"
 
+#include "cmStringAlgorithms.h"
+
 #include <utility>
 
 class cmMakefile;
@@ -18,8 +20,7 @@ std::string cmExternalMakefileProjectGenerator::CreateFullGeneratorName(
   std::string fullName;
   if (!globalGenerator.empty()) {
     if (!extraGenerator.empty()) {
-      fullName = extraGenerator;
-      fullName += " - ";
+      fullName = cmStrCat(extraGenerator, " - ");
     }
     fullName += globalGenerator;
   }