4.9.1: build is failing with Failed testing ocamlopt compiler

[kloczek]

I have no idea what is going on.
On upgarde my z3.spec file to suddelny build procedyure started failing in ocaml.

+ PYTHON=/usr/bin/python3
+ ./configure -p /usr --gmp --ml
opt = -p, arg = /usr
opt = --gmp, arg =
opt = --ml, arg =
New component: 'util'
New component: 'polynomial'
New component: 'interval'
New component: 'dd'
New component: 'simplex'
New component: 'hilbert'
New component: 'automata'
New component: 'realclosure'
New component: 'subpaving'
New component: 'ast'
New component: 'euf'
New component: 'params'
New component: 'smt_params'
New component: 'grobner'
New component: 'sat'
New component: 'nlsat'
New component: 'lp'
New component: 'rewriter'
New component: 'macros'
New component: 'normal_forms'
New component: 'model'
New component: 'tactic'
New component: 'substitution'
New component: 'parser_util'
New component: 'proofs'
New component: 'solver'
New component: 'cmd_context'
New component: 'smt2parser'
New component: 'pattern'
New component: 'aig_tactic'
New component: 'ackermannization'
New component: 'fpa'
New component: 'bit_blaster'
New component: 'core_tactics'
New component: 'arith_tactics'
New component: 'mbp'
New component: 'qe_lite'
New component: 'solver_assertions'
New component: 'sat_smt'
New component: 'sat_tactic'
New component: 'nlsat_tactic'
New component: 'subpaving_tactic'
New component: 'proto_model'
New component: 'smt'
New component: 'bv_tactics'
New component: 'fuzzing'
New component: 'smt_tactic'
New component: 'sls_tactic'
New component: 'qe'
New component: 'sat_solver'
New component: 'fd_solver'
New component: 'muz'
New component: 'dataflow'
New component: 'transforms'
New component: 'rel'
New component: 'spacer'
New component: 'clp'
New component: 'tab'
New component: 'ddnf'
New component: 'bmc'
New component: 'fp'
New component: 'smtlogic_tactics'
New component: 'ufbv_tactic'
New component: 'fpa_tactics'
New component: 'portfolio'
New component: 'opt'
New component: 'api'
New component: 'extra_cmds'
New component: 'shell'
New component: 'test'
New component: 'api_dll'
New component: 'dotnet'
New component: 'java'
New component: 'ml'
New component: 'cpp'
Python bindings directory was detected.
New component: 'python'
New component: 'python_install'
New component: 'js'
New component: 'cpp_example'
New component: 'z3_tptp'
New component: 'c_example'
New component: 'maxsat'
New component: 'dotnet_example'
New component: 'java_example'
New component: 'ml_example'
New component: 'py_example'
Generating src/util/z3_version.h from src/util/z3_version.h.in
Generated 'src/util/z3_version.h'
Generated 'src/ackermannization/ackermannization_params.hpp'
Generated 'src/ackermannization/ackermannize_bv_tactic_params.hpp'
Generated 'src/ast/pp_params.hpp'
Generated 'src/ast/normal_forms/nnf_params.hpp'
Generated 'src/math/polynomial/algebraic_params.hpp'
Generated 'src/math/realclosure/rcf_params.hpp'
Generated 'src/model/model_evaluator_params.hpp'
Generated 'src/model/model_params.hpp'
Generated 'src/muz/base/fp_params.hpp'
Generated 'src/nlsat/nlsat_params.hpp'
Generated 'src/opt/opt_params.hpp'
Generated 'src/params/arith_rewriter_params.hpp'
Generated 'src/params/array_rewriter_params.hpp'
Generated 'src/params/bool_rewriter_params.hpp'
Generated 'src/params/bv_rewriter_params.hpp'
Generated 'src/params/fpa2bv_rewriter_params.hpp'
Generated 'src/params/fpa_rewriter_params.hpp'
Generated 'src/params/pattern_inference_params_helper.hpp'
Generated 'src/params/poly_rewriter_params.hpp'
Generated 'src/params/rewriter_params.hpp'
Generated 'src/params/seq_rewriter_params.hpp'
Generated 'src/parsers/util/parser_params.hpp'
Generated 'src/sat/sat_asymm_branch_params.hpp'
Generated 'src/sat/sat_params.hpp'
Generated 'src/sat/sat_scc_params.hpp'
Generated 'src/sat/sat_simplifier_params.hpp'
Generated 'src/smt/params/smt_params_helper.hpp'
Generated 'src/solver/combined_solver_params.hpp'
Generated 'src/solver/parallel_params.hpp'
Generated 'src/solver/solver_params.hpp'
Generated 'src/tactic/tactic_params.hpp'
Generated 'src/tactic/sls/sls_params.hpp'
Generated 'src/tactic/smtlogics/qfufbv_tactic_params.hpp'
Generated 'src/ast/pattern/database.h'
Component api
Component portfolio
Component smtlogic_tactics
Component ackermannization
Component model
Component rewriter
Component ast
Component util
Component polynomial
Component automata
Component params
Component macros
Component solver
Component tactic
Component proofs
Component sat_solver
Component core_tactics
Component normal_forms
Component pattern
Component smt2parser
Component cmd_context
Component parser_util
Component aig_tactic
Component bv_tactics
Component bit_blaster
Component arith_tactics
Component sat
Component dd
Component interval
Component grobner
Component simplex
Component sat_tactic
Component sat_smt
Component euf
Component smt_params
Component fpa
Component mbp
Component lp
Component nlsat
Component qe_lite
Component nlsat_tactic
Component smt_tactic
Component smt
Component proto_model
Component solver_assertions
Component substitution
Component fp
Component muz
Component qe
Component clp
Component transforms
Component hilbert
Component dataflow
Component tab
Component rel
Component bmc
Component fd_solver
Component ddnf
Component spacer
Component ufbv_tactic
Component fpa_tactics
Component sls_tactic
Component subpaving_tactic
Component subpaving
Component realclosure
Component opt
Component extra_cmds
Component shell
Generated 'src/shell/install_tactic.cpp'
Component api
Component portfolio
Component smtlogic_tactics
Component ackermannization
Component model
Component rewriter
Component ast
Component util
Component polynomial
Component automata
Component params
Component macros
Component solver
Component tactic
Component proofs
Component sat_solver
Component core_tactics
Component normal_forms
Component pattern
Component smt2parser
Component cmd_context
Component parser_util
Component aig_tactic
Component bv_tactics
Component bit_blaster
Component arith_tactics
Component sat
Component dd
Component interval
Component grobner
Component simplex
Component sat_tactic
Component sat_smt
Component euf
Component smt_params
Component fpa
Component mbp
Component lp
Component nlsat
Component qe_lite
Component nlsat_tactic
Component smt_tactic
Component smt
Component proto_model
Component solver_assertions
Component substitution
Component fp
Component muz
Component qe
Component clp
Component transforms
Component hilbert
Component dataflow
Component tab
Component rel
Component bmc
Component fd_solver
Component ddnf
Component spacer
Component ufbv_tactic
Component fpa_tactics
Component sls_tactic
Component subpaving_tactic
Component subpaving
Component realclosure
Component opt
Component fuzzing
Component test
Generated 'src/test/install_tactic.cpp'
Component api
Component portfolio
Component smtlogic_tactics
Component ackermannization
Component model
Component rewriter
Component ast
Component util
Component polynomial
Component automata
Component params
Component macros
Component solver
Component tactic
Component proofs
Component sat_solver
Component core_tactics
Component normal_forms
Component pattern
Component smt2parser
Component cmd_context
Component parser_util
Component aig_tactic
Component bv_tactics
Component bit_blaster
Component arith_tactics
Component sat
Component dd
Component interval
Component grobner
Component simplex
Component sat_tactic
Component sat_smt
Component euf
Component smt_params
Component fpa
Component mbp
Component lp
Component nlsat
Component qe_lite
Component nlsat_tactic
Component smt_tactic
Component smt
Component proto_model
Component solver_assertions
Component substitution
Component fp
Component muz
Component qe
Component clp
Component transforms
Component hilbert
Component dataflow
Component tab
Component rel
Component bmc
Component fd_solver
Component ddnf
Component spacer
Component ufbv_tactic
Component fpa_tactics
Component sls_tactic
Component subpaving_tactic
Component subpaving
Component realclosure
Component opt
Component extra_cmds
Component api_dll
Generated 'src/api/dll/install_tactic.cpp'
Generated 'src/shell/mem_initializer.cpp'
Generated 'src/test/mem_initializer.cpp'
Generated 'src/api/dll/mem_initializer.cpp'
Generated 'src/shell/gparams_register_modules.cpp'
Generated 'src/test/gparams_register_modules.cpp'
Generated 'src/api/dll/gparams_register_modules.cpp'
Generated 'src/api/python/z3/z3consts.py
Generated 'src/api/api_log_macros.h'
Generated 'src/api/api_log_macros.cpp'
Generated 'src/api/api_commands.cpp'
Generated 'src/api/python/z3/z3core.py'
Generated "src/api/ml/z3native.ml"
Generated "src/api/ml/z3native_stubs.c"
Listing 'src/api/python/z3'...
Compiling 'src/api/python/z3/__init__.py'...
Compiling 'src/api/python/z3/z3.py'...
Compiling 'src/api/python/z3/z3consts.py'...
Compiling 'src/api/python/z3/z3core.py'...
Compiling 'src/api/python/z3/z3num.py'...
Compiling 'src/api/python/z3/z3poly.py'...
Compiling 'src/api/python/z3/z3printer.py'...
Compiling 'src/api/python/z3/z3rcf.py'...
Compiling 'src/api/python/z3/z3types.py'...
Compiling 'src/api/python/z3/z3util.py'...
Generated python bytecode
Copied '__init__.py'
Copied 'z3.py'
Copied 'z3num.py'
Copied 'z3poly.py'
Copied 'z3printer.py'
Copied 'z3rcf.py'
Copied 'z3types.py'
Copied 'z3util.py'
Copied 'z3consts.py'
Copied 'z3core.py'
Copied '__init__.cpython-38.pyc'
Copied 'z3.cpython-38.pyc'
Copied 'z3consts.cpython-38.pyc'
Copied 'z3core.cpython-38.pyc'
Copied 'z3num.cpython-38.pyc'
Copied 'z3poly.cpython-38.pyc'
Copied 'z3printer.cpython-38.pyc'
Copied 'z3rcf.cpython-38.pyc'
Copied 'z3types.cpython-38.pyc'
Copied 'z3util.cpython-38.pyc'
Testing ocamlc...
Testing ocamlopt...
Traceback (most recent call last):
  File "scripts/mk_make.py", line 18, in <module>
    mk_bindings(API_files)
  File "/home/tkloczko/rpmbuild/BUILD/z3-z3-4.9.1/scripts/mk_util.py", line 3054, in mk_bindings
    check_ml()
  File "/home/tkloczko/rpmbuild/BUILD/z3-z3-4.9.1/scripts/mk_util.py", line 464, in check_ml
    raise MKException('Failed testing ocamlopt compiler. Set environment variable OCAMLOPT with the path to the Ocaml native compiler. Note that ocamlopt may require flexlink to be in your path.')
mk_exception.MKException: 'Failed testing ocamlopt compiler. Set environment variable OCAMLOPT with the path to the Ocaml native compiler. Note that ocamlopt may require flexlink to be in your path.'