[llvm] [mlir] [Support] Accept only true, false, 1 and 0 for cl::opt<bool> (PR #224975)

[Fangrui Song via llvm-commits]

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@@ -439,13 +439,13 @@ static CommandLineParser &globalParser() {
 
 template <typename T, T TrueVal, T FalseVal>
 static bool parseBool(Option &O, StringRef ArgName, StringRef Arg, T &Value) {
-  if (Arg == "" || Arg == "true" || Arg == "TRUE" || Arg == "True" ||
-      Arg == "1") {
+  // A bare -flag passes a null Arg; -flag= passes an empty one.
+  if (!Arg.data() || Arg == "true" || Arg == "1") {
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MaskRay wrote:

`!Arg.data()` is intentional. To reject `-flag=`, we should test `!Arg.data()` here.

When `ProvideOption → addOccurrence → parser<bool>::parse → parseBool` runs:

  - `-flag` → Arg.data() == nullptr (null, "no value given")
  - `-flag=` → Arg.data() != nullptr && Arg.empty() (an explicitly empty value)
  - `-flag=x` → "x"



https://github.com/llvm/llvm-project/pull/224975