Revert "[FileCheck] Make invalid prefix diagnostics more precise"

This reverts commit a78e13745d4ee4a42e41ebbe698159f651515fc5 to try to
fix a bot:

http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/23489

1 files changed, 18 insertions, 22 deletions

diff --git a/llvm/lib/Support/FileCheck.cpp b/llvm/lib/Support/FileCheck.cpp
index 369b6df..b89cdfe 100644
--- a/llvm/lib/Support/FileCheck.cpp
+++ b/llvm/lib/Support/FileCheck.cpp
@@ -1874,37 +1874,33 @@ size_t FileCheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
   return StartPos;
 }
 
-static bool ValidatePrefixes(StringSet<> &UniquePrefixes,
-                             ArrayRef<StringRef> SuppliedPrefixes) {
-  for (StringRef Prefix : SuppliedPrefixes) {
-    if (Prefix.empty()) {
-      errs() << "error: supplied check prefix must not be the empty string\n";
+// A check prefix must contain only alphanumeric, hyphens and underscores.
+static bool ValidateCheckPrefix(StringRef CheckPrefix) {
+  static const Regex Validator("^[a-zA-Z0-9_-]*$");
+  return Validator.match(CheckPrefix);
+}
+
+bool FileCheck::ValidateCheckPrefixes() {
+  StringSet<> PrefixSet;
+
+  for (StringRef Prefix : Req.CheckPrefixes) {
+    // Reject empty prefixes.
+    if (Prefix.empty())
       return false;
-    }
-    static const Regex Validator("^[a-zA-Z0-9_-]*$");
-    if (!Validator.match(Prefix)) {
-      errs() << "error: supplied check prefix must start with a letter and "
-             << "contain only alphanumeric characters, hyphens, and "
-             << "underscores: '" << Prefix << "'\n";
+
+    if (!PrefixSet.insert(Prefix).second)
       return false;
-    }
-    if (!UniquePrefixes.insert(Prefix).second) {
-      errs() << "error: supplied check prefix must be unique among check "
-             << "prefixes: '" << Prefix << "'\n";
+
+    if (!ValidateCheckPrefix(Prefix))
       return false;
-    }
   }
-  return true;
-}
 
-bool FileCheck::ValidateCheckPrefixes() {
-  StringSet<> UniquePrefixes;
-  if (!ValidatePrefixes(UniquePrefixes, Req.CheckPrefixes))
-    return false;
   return true;
 }
 
 Regex FileCheck::buildCheckPrefixRegex() {
+  // I don't think there's a way to specify an initial value for cl::list,
+  // so if nothing was specified, add the default
   if (Req.CheckPrefixes.empty()) {
     Req.CheckPrefixes.push_back("CHECK");
     Req.IsDefaultCheckPrefix = true;