Based on llvm 18.1.0-rc2.

Since the API changes are based on LLVM 18.1.0-rc2, this
is currently tagged as a prerelease (-rc2) crate.

Link system libraries based on crt-static feature.

See merge request !43

fix LLVMTargetMachineEmitToFile signature

See merge request taricorp/llvm-sys.rs!44

Since the API changes are based on LLVM 19.1.0-rc1, this
is currently tagged as a prerelease (-rc1) crate.

This is needed to ensure that additional libraries such as zstd are
found when building.

Homebrew installs LLVM in non-standard locations, and compilers won't
find the necessary libraries without fiddling around with `brew link`,
PATH, and LIBRARY_PATH.

This updates the build script such that it tries to automatically detect
the necessary paths when using Homebrew, removing the need for any
manual intervention.

Make it easier to build on macOS and FreeBSD

See merge request taricorp/llvm-sys.rs!45

I find I need to look at the implementation to figure out how
to use this script every time I use it, so make it print help
to avoid that.

Same as the backport script, I never remember how to use it.

Greater distro compatibility is probably more worthwhile than
guaranteed static linking. Closes #65.

nisbet-hubbard authored Aug 16, 2024 and Peter Marheine committed Aug 17, 2024

These distros provide llvm-config in their llvm-devel package.

Before this change, build.rs had two problems which were making it
impossible to build on different musl-based Linux environments:

- It was assuming that the C++ library on all musl-based systems is
  LLVM libc++.
  - In the most cases, it's the opposite. LLVM packaged in Alpine is
    linked against GNU libstdc++, as well as LLVM tarballs in Rust CI.
  - Gentoo with musl-llvm profile, even though it links LLVM against
    libc++, has a different name for the system-wide static library
    (`/usr/lib/libc++_static.a` instead of `/usr/lib/libc++.a`, which
    is a link script).
- When linking runtime libraries statically (`crt-static`), Cargo doesn't
  look for the system-wide static libraries in `/usr/lib`, unless that
  directory is added to the link flags with `-L`.

The first point is addressed by:

- Linking to libstdc++ by default, even for musl systems.
- Ability to override that choice with `LLVM_SYS_LIBCPP` environment
  variable for environments which use LLVM libc++.

The second point is addressed by:

- Adding `/usr/lib` and other system dirs to `cargo::rustc-link-search`
  on Linux with `crt-static` builds.
- Exposing `LLVM_SYS_SYSTEM_LIBRARY_DIRS` environment variable, where
  callers can add additional paths.

After this change, building llvm-sys on Alpine can be done just with
the usual `cargo build` and `LLVM_SYS_191_PREFIX` variable pointing to
the LLVM 19 prefix. In CI, we are using Rust CI tarballs for that.

On any Linux environment where LLVM is linked against libc++, llvm-sys
can be built with:

```
LLVM_SYS_LIBCPP=c++ cargo build --no-default-features
```

Building llvm-sys Gentoo with llvm-musl profile, where libc++ static
library is called `libc++_static.a` and it needs `libc++abi.a` to work,
can be done with:

```
LLVM_SYS_LIBCPP=c++_static RUSTFLAGS="-lc++abi" cargo test --no-default-features
```

Unfortunately, the latter configurations are not tested in CI - as for
now, there are no publicly available libLLVM binary blobs linked against
LLVM libc++ - such configuration requires compilation of LLVM.

build: Fix build for variety of musl-based Linux distributions

See merge request taricorp/llvm-sys.rs!46

This is a new warning in (or around) Rust 1.80.

llvm.sh seems to have started not installing llvm-$VERSION-dev by
default, which leaves llvm-config unavailable so our builds fail.

The requirement for rust 1.65 is inherited from the regex-lite
dependency, and upgrading beyond the 2015 edition currently requires
code changes to handle changed import rules in Rust 2018.

Use the `c_char` type instead of `i8` - the type used as `char` (signed
or unsigned) differs across architectures.

Improve portability of examples (was: support cross-compilation)

See merge request taricorp/llvm-sys.rs!49

See also https://github.com/llvm/llvm-project/pull/99087

add LLVMGetValueContext and LLVMGetBuilderContext

See merge request taricorp/llvm-sys.rs!51

Seems we're past the limit of the retention period; bump the revision to
a slightly newer one to revive our CI.

See https://rust-lang.github.io/rust-clippy/master/index.html#deprecated_semver.

This applies some clippy-suggested fixes for style, notably changing `since`
in deprecations to refer to a crate version rather than LLVM version. The
rust snapshot hash is also updated to one that still exists.

See merge request !52

Since the API changes are based on LLVM 20.1.0-rc1, this is currently
tagged as a prerelease (-rc1) crate.

Update for LLVM 20

See merge request taricorp/llvm-sys.rs!53

This change fixes the build script's logic for resolving library
paths into linker flags when llvm-config returns the path to
a static archive; apparently some configurations will behave
this way.

Fixes #75.

There's work upstream on enabling this, so point to the upstream
issue to ease tracking.

Since the API changes are based on LLVM 21.1.0-rc1, this is currently
tagged as a prerelase (-rc1) crate.

Update for LLVM 21

See merge request taricorp/llvm-sys.rs!55