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/cmCPluginAPI.cxx b/Source/cmCPluginAPI.cxx
index d06ec20..f0c1845 100644
--- a/Source/cmCPluginAPI.cxx
+++ b/Source/cmCPluginAPI.cxx
@@ -690,9 +690,7 @@ void CCONV cmSourceFileSetName(void* arg, const char* name, const char* dir,
 
   // Next, try the various source extensions
   for (std::string const& ext : sourceExts) {
-    hname = pathname;
-    hname += ".";
-    hname += ext;
+    hname = cmStrCat(pathname, '.', ext);
     if (cmSystemTools::FileExists(hname)) {
       sf->SourceExtension = ext;
       sf->FullPath = hname;
@@ -702,9 +700,7 @@ void CCONV cmSourceFileSetName(void* arg, const char* name, const char* dir,
 
   // Finally, try the various header extensions
   for (std::string const& ext : headerExts) {
-    hname = pathname;
-    hname += ".";
-    hname += ext;
+    hname = cmStrCat(pathname, '.', ext);
     if (cmSystemTools::FileExists(hname)) {
       sf->SourceExtension = ext;
       sf->FullPath = hname;