[Support] Add MIR YAML parsing infrastructure

Introduce source ranges, deterministic text diagnostics, and an independently authored YAML stream parser for the fixed LLVM MIR container shapes. Record the compatibility matrix and Stage 6 validation state.

1 files changed, 43 insertions, 0 deletions

diff --git a/backend/unittests/Support/TextDiagnosticTest.cpp b/backend/unittests/Support/TextDiagnosticTest.cpp
new file mode 100644
index 0000000..cd28027
--- /dev/null
+++ b/backend/unittests/Support/TextDiagnosticTest.cpp
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/Support/TextDiagnostic.h"
+
+#include <iostream>
+#include <string>
+
+namespace {
+
+int fail(const char *Message) {
+  std::cerr << Message << '\n';
+  return 1;
+}
+
+} // namespace
+
+int main() {
+  rcc::TextSource Source("input.mir", "first\r\nsecond line\n");
+  if (Source.lineCount() != 3)
+    return fail("TextSource must index every physical line");
+  if (Source.line(1) != "first" || Source.line(2) != "second line" || !Source.line(3).empty())
+    return fail("TextSource must expose lines without line endings");
+
+  const rcc::TextRange Range = Source.range(9, 15);
+  if (Range.Begin.Line != 2 || Range.Begin.Column != 3 || Range.End.Line != 2 ||
+      Range.End.Column != 9)
+    return fail("TextSource must map byte offsets to one-based line and column values");
+
+  const rcc::TextDiagnostic Diagnostic{
+      .Severity = rcc::DiagnosticSeverity::Error,
+      .Category = "yaml",
+      .Message = "invalid scalar",
+      .SourceName = "input.mir",
+      .Range = Range,
+  };
+  const std::string Formatted = rcc::formatTextDiagnostic(Diagnostic, Source);
+  if (Formatted != "input.mir:2:3: error[yaml]: invalid scalar\nsecond line\n  ^~~~~~")
+    return fail("Text diagnostics must have deterministic source rendering");
+
+  if (rcc::getDiagnosticSeverityName(rcc::DiagnosticSeverity::Warning) != "warning")
+    return fail("Diagnostic severities must have stable names");
+  return 0;
+}