[MLIR] ArrayRefParameter together with struct printing breaks print + parse roundtrip

[Dinistro]

Using ArrayRefParameter together with a struct(params) assembly format can result in a broken printer and parser pair. If one adds another attribute after the ArrayRef parameter, things start to fail.

For example, the following attribute

def Repro_Attr : LLVM_Attr<"ReproAttr", "repro", []> {
  let parameters = (ins
    ArrayRefParameter<"IntegerAttr">:$elements,
    OptionalParameter<"StringAttr">:$str,
  );

  let assemblyFormat = "`<` struct(params) `>`";
}

could print as

#llvm.repro<elements = 32 : i64, str = "bar">

which then explodes during parsing.

I assume that a potential fix for this would be to print the ArrayRefParameter with some brackets, to avoid any ambiguities.

[llvmbot]

@llvm/issue-subscribers-mlir

Author: Christian Ulmann (Dinistro)

Using `OptionalArrayRefParameter` together with a `struct(params)` assembly format can result in a broken printer and parser pair. If one adds another attribute **after** the ArrayRef parameter, things start to fail.

For example, the following attribute

def Repro_Attr : LLVM_Attr<"ReproAttr", "repro", []> {
  let parameters = (ins
    OptionalArrayRefParameter<"IntegerAttr">:$elements,
    OptionalParameter<"StringAttr">:$str,
  );

  let assemblyFormat = "`<` struct(params) `>`";
}

could print as

#llvm.repro<elements = 32 : i64, str = "bar">

which then explodes during parsing.

I assume that a potential fix for this would be to print the ArrayRefParameter with some brackets, to avoid any ambiguities.