cmake: the setup hook breaks with __structuredAttrs = true

[fgaz]

Describe the bug

The cmake setup hook breaks with __structuredAttrs = true.

Steps To Reproduce

Write a derivation that uses cmake with __structuredAttrs = true and set cmakeFlags to a list with >1 element.
The build hook always treats $cmakeFlags as a normal variable, so it uses only the first array element.

Expected behavior

The flags get passed to cmake

Screenshots

If applicable, add screenshots to help explain your problem.

Additional context

Solution used in the npm hook:

nixpkgs/pkgs/build-support/node/build-npm-package/hooks/npm-install-hook.sh

Lines 17 to 26 in 0855890

	# Based on code from Python's buildPythonPackage wrap.sh script, for
	# supporting both the case when makeWrapperArgs is an array and a
	# IFS-separated string.
	#
	# TODO: remove the string branch when __structuredAttrs are used.
	if [[ "${makeWrapperArgs+defined}" == "defined" && "$(declare -p makeWrapperArgs)" =~ ^'declare -a makeWrapperArgs=' ]]; then
	local -a user_args=("${makeWrapperArgs[@]}")
	else
	local -a user_args="(${makeWrapperArgs:-})"
	fi

Workaround: use cmakeFlagsArray instead.

Notify maintainers

@teto @ttuegel @LnL7 @AndersonTorres

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
output here

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[wolfgangwalther]

I just noticed the same happens for the meson setup hook and mesonFlags.