[MLIR] Add context accessor to identifier

[GeorgeLyon]

Summary

I knew I would miss one...

mlir/include/mlir-c/IR.h

 //===----------------------------------------------------------------------===//
 // Identifier API.
 //===----------------------------------------------------------------------===//
 
 /// Gets an identifier with the given string value.
 MLIR_CAPI_EXPORTED MlirIdentifier mlirIdentifierGet(MlirContext context,
                                                     MlirStringRef str);
 
+/// Returns the context associated with this identifier
+MLIR_CAPI_EXPORTED MlirContext mlirIdentifierGetContext(MlirIdentifier);
+
 /// Checks whether two identifiers are the same.
 MLIR_CAPI_EXPORTED bool mlirIdentifierEqual(MlirIdentifier ident,
                                             MlirIdentifier other);
 
 /// Gets the string value of the identifier.
 MLIR_CAPI_EXPORTED MlirStringRef mlirIdentifierStr(MlirIdentifier ident);
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif // MLIR_C_IR_H

mlir/lib/CAPI/IR/IR.cpp

 //===----------------------------------------------------------------------===//
 // Identifier API.
 //===----------------------------------------------------------------------===//
 
 MlirIdentifier mlirIdentifierGet(MlirContext context, MlirStringRef str) {
   return wrap(Identifier::get(unwrap(str), unwrap(context)));
 }
 
+MlirContext mlirIdentifierGetContext(MlirIdentifier ident) {
+  return wrap(unwrap(ident).getContext());
+}
+
 bool mlirIdentifierEqual(MlirIdentifier ident, MlirIdentifier other) {
   return unwrap(ident) == unwrap(other);
 }
 
 MlirStringRef mlirIdentifierStr(MlirIdentifier ident) {
   return wrap(unwrap(ident).strref());
 }

mlir/test/CAPI/ir.c

static int testBackreferences() {
   MlirLocation loc = mlirLocationUnknownGet(ctx);
 
   MlirOperationState opState = mlirOperationStateGet(mlirStringRefCreateFromCString("invalid.op"), loc);
   MlirRegion region = mlirRegionCreate();
   MlirBlock block = mlirBlockCreate(0, NULL);
   mlirRegionAppendOwnedBlock(region, block);
   mlirOperationStateAddOwnedRegions(&opState, 1, &region);
   MlirOperation op = mlirOperationCreate(&opState);
+  MlirIdentifier ident = mlirIdentifierGet(ctx, mlirStringRefCreateFromCString("identifier"));
 
   if (!mlirContextEqual(ctx, mlirOperationGetContext(op))) {
     fprintf(stderr, "ERROR: Getting context from operation failed\n");
     return 1;
   }
   if (!mlirOperationEqual(op, mlirBlockGetParentOperation(block))) {
     fprintf(stderr, "ERROR: Getting parent operation from block failed\n");
     return 2;
   }
+  if (!mlirContextEqual(ctx, mlirIdentifierGetContext(ident))) {
+    fprintf(stderr, "ERROR: Getting context from identifier failed\n");
+    return 3;
+  }
   
   mlirOperationDestroy(op);
   mlirContextDestroy(ctx);
 
   // CHECK-LABEL: @test_backreferences
   return 0;
 }