[Mlir-commits] [mlir] [MLIR] Print (u)int8_t args as numbers and properly support char args (PR #225680)

[Henrich Lauko]

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@@ -110,6 +110,38 @@ struct FieldParser<
   }
 };
 
+/// Parse a plain `char` as a single-character keyword-or-string. Identifier
+/// characters (e.g. `A`) are accepted as bare keywords; all other values use a
+/// quoted+escaped string with two-digit hex escapes (e.g. `"\0A"` for newline),
+/// covering all 256 byte values. Named escapes such as `\n` are also accepted
+/// as input but are not the canonical printed form.
+template <>
+struct FieldParser<char> {
+  static FailureOr<char> parse(AsmParser &parser) {
+    std::string str;
+    auto loc = parser.getCurrentLocation();
+    if (parser.parseKeywordOrString(&str))
+      return failure();
+    if (str.size() != 1)
+      return parser.emitError(loc, "expected a single character");
+    return str[0];
+  }
+};
+
+/// Parse a plain `char` wrapped in optional — delegates to FieldParser<char>
+/// so that optional char params use keyword-or-string, matching the printer.
+template <>
+struct FieldParser<std::optional<char>> {
+  static constexpr bool isKeyValueCompositional = false;
+
+  static FailureOr<std::optional<char>> parse(AsmParser &parser) {
+    auto result = FieldParser<char>::parse(parser);
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xlauko wrote:

This is uncoditional parse, I think it should use `parseOptionalKeywordOrString`.

https://github.com/llvm/llvm-project/pull/225680