[clang-tools-extra] create new clang-tidy check to add namespaces to symbol references (PR #70621)

[via cfe-commits]

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+.. title:: clang-tidy - readability-use-explicit-namespaces
+
+readability-use-explicit-namespaces
+===================================
+
+This check detects and fixes references to members of namespaces where the namespace is not explicity specified in the reference.  By default, this will only change references that are found through a using namespace directive.
+
+Example:
+using namespace std;
+using std::string;
+string something = "something";
+cout << something;
+
+
+Fixed:
+using namespace std;
+using std::string;
+string something = "something";    // this is not change by default because it is referenced through using std::string instead of using namespace std
+std::cout << something;
+
+Options:
----------------
EugeneZelenko wrote:

See other documentation for options examples.

https://github.com/llvm/llvm-project/pull/70621