[clang] [-Wunsafe-buffer-usage] Introduce std::array fixits (PR #80084)

[via cfe-commits]

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@@ -61,6 +61,7 @@ void testArraySubscripts(int *p, int **pp) {
       );
 
     int a[10];          // expected-warning{{'a' is an unsafe buffer that does not perform bounds checks}}
+                        // expected-note at -1{{change type of 'a' to 'std::array' to harden it}}
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jkorous-apple wrote:

I guess what we really want to say is "change the type of 'foo' to std::array so when you build the code with hardened libc++ all subscript operations on 'foo' will be automatically bounds-safe" but that is too long and too complex for this particular communication channel.

How about:
"to enable hardening"
"to get it hardened"
"to designate it for hardening"
"to register it for hardening"

https://github.com/llvm/llvm-project/pull/80084