When built as a static library, sqlite (or sqlcipher) doesn't carry
additional link dependencies with it, and the libsqlite3-sys rlib
doesn't pick them up either. A dependent crate attempting to link
against rusqlite then has to specify these additional link commands,
and even then they need to be specified before the libsqlite3-sys
rlib is specified on the command line.
Fix this by attempting to use pkg-config when the
(SQLITE3|SQLCIPHER)_LIB_DIR is specified, since these builds produce
the pkg-config link dependency information, and the pkg_config crate
can automatically generate the correct link commands using that.
(Additionally, since (SQLITE3|SQLCIPHER)_STATIC is already defined,
or not, the --static flag will be correctly configured for pkg_config)
This also required adjusting the fixup inserting `SQLITE_DETERMINISTIC` into the
bindings if it was missing. Now that `bindgen` uses the `quote` crate for code
generation, instead of `syntex`, we can't rely on the output being formatted (it
only is formatted if there is a usable `rustfmt` on the `$PATH`). Even better
than this `contains` tweak would be switching to regexps or something.
Despite that formatting hiccup, newer `bindgen` releases are more reliable due
to many bug fixes, and also build in approximately half the time that older
`bindgen` versions do.
Recent versions of bindgen use `std::os::raw` over `libc`, but currently
`libsqlite3-sys` is overriding that. `std::os::raw` is a subset of
`libc` that exports only the relevant type definitions, but not any
functions which require additional linking. This enables
`libsqlite3-sys` to be more easily used on targets that may not have a
libc available (presumably sqlite itself would have been compiled with
musl in that case)
See comment in libsqlite3-sys/build.rs for details - adding this flag is
harmless if it's not present in the header, and not having it can break
builds against older SQLite versions.
* If SQLITE3_LIB_DIR is present in the environment, we use that.
* If SQLITE3_LIB_DIR is not present, we try to use pkg-config.
* If SQLITE3_LIB_DIR is not present and pkg-config fails, we fall back
to /usr/lib (if it exists).
