[mlir][EmitC] func-to-emitc: Fix conversion for call ops with zero arguments

Author: Simon Camphausen

mlir/lib/Conversion/FuncToEmitC/FuncToEmitC.cpp

@@ -38,7 +38,7 @@ class CallOpConversion final : public OpConversionPattern<func::CallOp> {
 
     rewriter.replaceOpWithNewOp<emitc::CallOp>(
         callOp,
-        callOp.getNumResults() ? callOp.getResult(0).getType() : nullptr,
+        callOp.getNumResults() ? callOp.getResult(0).getType() : TypeRange{},
         adaptor.getOperands(), callOp->getAttrs());
 
     return success();

mlir/test/Conversion/FuncToEmitC/func-to-emitc.mlir

@@ -58,3 +58,19 @@ func.func @call(%arg0: i32) -> i32 {
 
 // CHECK-LABEL: emitc.func private @return_i32(i32) -> i32 attributes {specifiers = ["extern"]}
 func.func private @return_i32(%arg0: i32) -> i32
+
+// -----
+
+// CHECK-LABEL: emitc.func private @return_void() attributes {specifiers = ["static"]}
+// CHECK-NEXT: emitc.return
+func.func private @return_void() {
+  return
+}
+
+// CHECK-LABEL: emitc.func @call()
+// CHECK-NEXT: emitc.call @return_void() : () -> ()
+// CHECK-NEXT: emitc.return
+func.func @call() {
+  call @return_void() : () -> ()
+  return
+}