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, 4 deletions

diff --git a/Source/cmakemain.cxx b/Source/cmakemain.cxx
index a210959..2b51a2a 100644
--- a/Source/cmakemain.cxx
+++ b/Source/cmakemain.cxx
@@ -138,11 +138,9 @@ void cmakemainProgressCallback(const std::string& m, float prog, cmake* cm)
   cmMakefile* mf = cmakemainGetMakefile(cm);
   std::string dir;
   if (mf && cmHasLiteralPrefix(m, "Configuring") && (prog < 0)) {
-    dir = " ";
-    dir += mf->GetCurrentSourceDirectory();
+    dir = cmStrCat(' ', mf->GetCurrentSourceDirectory());
   } else if (mf && cmHasLiteralPrefix(m, "Generating")) {
-    dir = " ";
-    dir += mf->GetCurrentBinaryDirectory();
+    dir = cmStrCat(' ', mf->GetCurrentBinaryDirectory());
   }
 
   if ((prog < 0) || (!dir.empty())) {