[llvm] [FileCheck] improve prefix validation (PR #92248)

[via llvm-commits]

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@@ -2468,24 +2468,36 @@ FileCheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
 
 static bool ValidatePrefixes(StringRef Kind, StringSet<> &UniquePrefixes,
                              ArrayRef<StringRef> SuppliedPrefixes) {
+  static const char *Suffixes[] = {"-NEXT",  "-SAME", "-EMPTY", "-NOT",
+                                   "-COUNT", "-DAG",  "-LABEL"};
+
   for (StringRef Prefix : SuppliedPrefixes) {
     if (Prefix.empty()) {
       errs() << "error: supplied " << Kind << " prefix must not be the empty "
              << "string\n";
       return false;
     }
-    static const Regex Validator("^[a-zA-Z0-9_-]*$");
+    // TODO: restrict prefixes to start with only letter eventually
+    static const Regex Validator("^[a-zA-Z0-9][a-zA-Z0-9_-]*$");
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klensy wrote:

I expected for prefixes to be kind-of-ident (which can't start from digits and dashes, but digits actually used, bc no check for that was added, oh, well), and be similar to substitution blocks (which should be `"[a-zA-Z_][0-9a-zA-Z_]*"`, as per doc).

Less restrictions makes it harder to catch possible errors in directives; currently possible typos simply ignored.

https://github.com/llvm/llvm-project/pull/92248