[MacPorts] #69138: rust @1.75.0 : Does not build on macOS 10.11.6 - missing _getentropy and _clock_gettime

[MacPorts]

#69138: rust @1.75.0 : Does not build on macOS 10.11.6 - missing  _getentropy and
_clock_gettime
------------------------+---------------------------------
  Reporter:  snowflake  |      Owner:  MarcusCalhoun-Lopez
      Type:  defect     |     Status:  closed
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:  2.8.99
Resolution:  fixed      |   Keywords:
      Port:  rust       |
------------------------+---------------------------------

Comment (by mqudsi):

 After playing around with this some and trying it out against real-world
 projects, I have unfortunately come to realize it might actually be
 necessary to patch the toolchain to apply this automatically to work
 around deficiencies in cargo's current abilities to specify linker flags
 when building transitive dependencies that include proc macros or build
 scripts (but only specifically where building for the host (i.e. sans
 `--target`) or where building with `--target x86_64-apple-darwin`).

 The problem is that Cargo intentionally does not pass through RUSTFLAGS to
 build scripts and proc macros (directly or in your transitive
 dependencies) if you build with an explicit `--target x86_64-apple-darwin`
 (or any other target), *and* there is no known workaround to pass through
 linker flags to the build scripts in this case. So for any rust project
 that has a `*-sys` crate in its (transitive) dependencies, the link stage
 will fail due to missing symbol errors and you can't do anything about it.

 I [[https://github.com/rust-lang/cargo/issues/13981|bugged it upstream]]
 and there's an active discussion going on, but it's tangential to
 [[https://github.com/rust-lang/cargo/issues/4423|a long-standing known
 issue]] with no resolution in sight.

 The only "solution" I found was to hack the build scripts to remove
 explicit `--target` from cargo calls then patch the install phase to copy
 artifacts out of `$BUILD_DIR/cargo/build/{debug,release}` instead of
 `$BUILD_DIR/cargo/build/x86_64-apple-darwin/{debug,release}`, but that's
 not really a workable solution.

 (I'm thinking in terms of solutions that would work to provide macports
 ports for projects written in rust that explicitly specify `--target` via
 their non-cargo build system on a target that requires LegacySupport.)

-- 
Ticket URL: <https://trac.macports.org/ticket/69138#comment:26>
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