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, 7 deletions

diff --git a/Source/cmSourceFile.cxx b/Source/cmSourceFile.cxx
index 3f52e643d6..a6d280718f 100644
--- a/Source/cmSourceFile.cxx
+++ b/Source/cmSourceFile.cxx
@@ -151,9 +151,7 @@ bool cmSourceFile::FindFullPath(std::string* error)
     for (auto exts : extsLists) {
       for (std::string const& ext : *exts) {
         if (!ext.empty()) {
-          std::string extPath = fullPath;
-          extPath += '.';
-          extPath += ext;
+          std::string extPath = cmStrCat(fullPath, '.', ext);
           if (cmSystemTools::FileExists(extPath)) {
             this->FullPath = extPath;
             return true;
@@ -178,10 +176,8 @@ bool cmSourceFile::FindFullPath(std::string* error)
   }
 
   // Compose error
-  std::string err;
-  err += "Cannot find source file:\n  ";
-  err += lPath;
-  err += "\nTried extensions";
+  std::string err =
+    cmStrCat("Cannot find source file:\n  ", lPath, "\nTried extensions");
   for (auto exts : extsLists) {
     for (std::string const& ext : *exts) {
       err += " .";