build: move to a Cargo workspace

This is purely to let Cargo's dependency resolver do stuff for us, we do
not actually intend to build this stuff with Cargo to begin with.

Change-Id: I4c08d55595c7c27b7096375022581e1e34308a87

.gitignore

@@ -9,6 +9,10 @@ GTAGS
 # ccls
 /.ccls-cache
 
+# auto-generated compilation database
+compile_commands.json
+rust-project.json
+
 result
 result-*
 
@@ -29,3 +33,6 @@ buildtime.bin
 /.pre-commit-config.yaml
 /.nocontribmsg
 /release
+
+# Rust build files when using Cargo (not actually supported for building but it spews the files anyway)
+/target/

Cargo.toml

@@ -0,0 +1,6 @@
+[workspace]
+resolver = "2"
+members = ["src/lix-doc"]
+
+[workspace.package]
+edition = "2021"

meson.build

@@ -545,6 +545,32 @@ if cxx.get_id() in ['clang', 'gcc']
   )
 endif
 
+# Until Meson 1.5¹, we can't just give Meson a Cargo.lock file and be done with it.
+# Meson will *detect* what dependencies are needed from Cargo files; it just won't
+# fetch them. The Meson 1.5 feature essentially internally translates Cargo.lock entries
+# to .wrap files, and that translation is incredibly straightforward, so let's just
+# use a simple Python script to generate the .wrap files ourselves while we wait for
+# Meson 1.5. Weirdly, it seems Meson will only detect dependencies from other
+# dependency() calls, so we have to specify lix-doc's two top-level dependencies,
+# rnix and rowan, manually, and then their dependencies will be recursively translated
+# into more dependency() calls.
+#
+# When Meson translates a Cargo dependency, the string passed to `dependency()` follows
+# a fixed format, which is important as the .wrap files' basenames must match the string
+# passed to `dependency()` exactly.
+# In Meson 1.4, this format is `$packageName-rs`. Meson 1.5 changes this to
+# `$packageName-$shortenedVersionString-rs`, because of course it does, but we'll cross
+# that bridge when we get there...
+#
+# [1]: https://github.com/mesonbuild/meson/commit/9b8378985dbdc0112d11893dd42b33b7bc8d1e62
+run_command(
+  python,
+  meson.project_source_root() / 'meson/cargo-lock-to-wraps.py',
+  meson.project_source_root() / 'Cargo.lock',
+  meson.project_source_root() / 'subprojects',
+  check : true,
+)
+
 if is_darwin
   configure_file(
     input : 'misc/launchd/org.nixos.nix-daemon.plist.in',

package.nix

@@ -137,6 +137,8 @@ let
     ./meson
     ./scripts/meson.build
     ./subprojects
+    # Required for meson to generate Cargo wraps
+    ./Cargo.lock
   ]);
 
   functionalTestFiles = fileset.unions [
@@ -288,7 +290,7 @@ stdenv.mkDerivation (finalAttrs: {
     BOOST_LIBRARYDIR = "${lib.getLib boost}/lib";
   };
 
-  cargoDeps = rustPlatform.importCargoLock { lockFile = ./src/lix-doc/Cargo.lock; };
+  cargoDeps = rustPlatform.importCargoLock { lockFile = ./Cargo.lock; };
 
   preConfigure =
     lib.optionalString (!finalAttrs.dontBuild && !hostPlatform.isStatic) ''

src/lix-doc/Cargo.toml

@@ -8,9 +8,6 @@ license = "BSD-2-Clause OR MIT"
 homepage = "https://github.com/lf-/nix-doc"
 repository = "https://github.com/lf-/nix-doc"
 
-[lib]
-crate_type = ["staticlib"]
-
 [dependencies]
 rnix = "0.11.0"
 # Necessary because rnix fails to export a critical trait (Rowan's AstNode).

src/lix-doc/meson.build

@@ -1,30 +1,3 @@
-# Until Meson 1.5¹, we can't just give Meson a Cargo.lock file and be done with it.
-# Meson will *detect* what dependencies are needed from Cargo files; it just won't
-# fetch them. The Meson 1.5 feature essentially internally translates Cargo.lock entries
-# to .wrap files, and that translation is incredibly straightforward, so let's just
-# use a simple Python script to generate the .wrap files ourselves while we wait for
-# Meson 1.5. Weirdly, it seems Meson will only detect dependencies from other
-# dependency() calls, so we have to specify lix-doc's two top-level dependencies,
-# rnix and rowan, manually, and then their dependencies will be recursively translated
-# into more dependency() calls.
-#
-# When Meson translates a Cargo dependency, the string passed to `dependency()` follows
-# a fixed format, which is important as the .wrap files' basenames must match the string
-# passed to `dependency()` exactly.
-# In Meson 1.4, this format is `$packageName-rs`. Meson 1.5 changes this to
-# `$packageName-$shortenedVersionString-rs`, because of course it does, but we'll cross
-# that bridge when we get there...
-#
-# [1]: https://github.com/mesonbuild/meson/commit/9b8378985dbdc0112d11893dd42b33b7bc8d1e62
-
-run_command(
-  python,
-  meson.project_source_root() / 'meson/cargo-lock-to-wraps.py',
-  meson.current_source_dir() / 'Cargo.lock',
-  meson.project_source_root() / 'subprojects',
-  check : true,
-)
-
 # The external crate rowan has an ambiguous pointer comparison warning, which
 # we don't want to fail our whole build if werror is on.
 subproject('rowan-rs', default_options : ['werror=false'])