[llvm] [mlir] [mlir] expose transform interpreter to Python (PR #82365)

[Maksim Levental via llvm-commits]

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@@ -569,6 +570,41 @@ class mlir_value_subclass : public pure_subclass {
 };
 
 } // namespace adaptors
+
+/// RAII scope intercepting all diagnostics into a string. The message must be
+/// checked before this goes out of scope.
+class CollectDiagnosticsToStringScope {
+public:
+  explicit CollectDiagnosticsToStringScope(MlirContext ctx) : context(ctx) {
+    handlerID = mlirContextAttachDiagnosticHandler(ctx, &handler, &errorMessage,
+                                                   /*deleteUserData=*/nullptr);
+  }
+  ~CollectDiagnosticsToStringScope() {
+    assert(errorMessage.empty() && "unchecked error message");
+    mlirContextDetachDiagnosticHandler(context, handlerID);
+  }
+
+  [[nodiscard]] std::string takeMessage() { return std::move(errorMessage); }
+
+private:
+  static MlirLogicalResult handler(MlirDiagnostic diag, void *data) {
+    auto printer = +[](MlirStringRef message, void *data) {
+      *static_cast<std::string *>(data) +=
+          llvm::StringRef(message.data, message.length);
+    };
+    MlirLocation loc = mlirDiagnosticGetLocation(diag);
+    *static_cast<std::string *>(data) += "at ";
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makslevental wrote:

Thanks :)

https://github.com/llvm/llvm-project/pull/82365