Add Yupei Qi's suggestion.

gen/generator.jl

@@ -10,7 +10,7 @@ options = load_options(joinpath(@__DIR__, "generator.toml"))
 
 args = get_default_args()
 push!(args, "-I$(hypre_include_dir)")
-push!(args, "-I$(mpi_include_dir)")
+push!(args, "-isystem$(mpi_include_dir)")
 
 # Compiler flags from Yggdrasil (??)
 # https://github.com/JuliaPackaging/Yggdrasil/blob/9d131ba0e4aa393b00f4d71ef5a3f909419a70a7/H/HYPRE/build_tarballs.jl

lib/LibHYPRE.jl

@@ -11,8 +11,6 @@ else # MPI < 0.20.0
 end
 
 
-mutable struct ADIOI_FileD end
-
 const HYPRE_BigInt = Cint
 
 const HYPRE_Int = Cint
@@ -3731,12 +3729,6 @@ const HYPRE_FMANGLE_LAPACK = 0
 
 const HYPRE_USING_HOST_MEMORY = 1
 
-const NO_TAGS_WITH_MODIFIERS = 1
-
-const ROMIO_VERSION = 126
-
-const HAVE_MPI_GREQUEST = 1
-
 const HYPRE_MPI_BIG_INT = MPI_INT
 
 const HYPRE_MPI_INT = MPI_INT