[BuildToolchains] Use <aatriplet>-cc as linker in Cargo config (#189)

I don't understand why we were forcing `gcc`, on `aarch64-apple-darwin` this
causes lots of trouble, because Cargo would pass in the argument `-arch arm64`
which isn't accepted by GCC, but it is by LLVM.

Now that we can JIT-generate the file, write the config only for host and target
platforms, we don't have the toolchains for the other platforms anyway.

Additionally, remove some workarounds previously added in `Runner.jl` to fix
errors in the old static config file.

Author: giordano

src/BuildToolchains.jl

@@ -254,20 +254,21 @@ function generate_toolchain_files!(platform::AbstractPlatform, envs::Dict{String
     end
 end
 
-function cargo_config_file!(dir::AbstractString)
-    # Generate "${CARGO_HOME}/config.toml" file for Cargo where we give it the
-    # linkers for all our targets
+function cargo_config_file!(dir::AbstractString, platform::AbstractPlatform;
+                            host_platform::AbstractPlatform=default_host_platform,
+                            )
+    # Generate "${CARGO_HOME}/config.toml" file for Cargo where we give it the linkers for
+    # the host and target platforms.
     open(joinpath(dir, "config.toml"), "w") do io
         write(io, """
         # Configuration file for `cargo`
         """)
-        for platform in supported_platforms(; experimental=true)
-            # Use `aatriplet` for the linker to match how the wrappers are
-            # written in
+        for p in unique(abi_agnostic.((platform, host_platform)))
+            # Use `aatriplet` for the linker to match how the wrappers are written in
             # https://github.com/JuliaPackaging/BinaryBuilderBase.jl/blob/30d056ef68f81dca9cb91ededcce6b68c6466b37/src/Runner.jl#L599.
             write(io, """
-            [target.$(map_rust_target(platform))]
-            linker = "$(aatriplet(platform))-gcc"
+            [target.$(map_rust_target(p))]
+            linker = "$(aatriplet(p))-cc"
             """)
         end
     end

src/DockerRunner.jl

@@ -103,7 +103,7 @@ function DockerRunner(workspace_root::String;
         # Generate directory where to write Cargo config files
         if isone(length(collect(compilers))) && :rust in collect(compilers)[1].second
             cargo_dir = mktempdir()
-            cargo_config_file!(cargo_dir)
+            cargo_config_file!(cargo_dir, platform)
             # Add to the list of mappings a subdirectory of ${CARGO_HOME}, whose content
             # will be put in ${CARGO_HOME}.
             push!(workspaces, cargo_dir => envs["CARGO_HOME"] * "/" * randstring())

src/Runner.jl

@@ -765,22 +765,6 @@ function generate_compiler_wrappers!(platform::AbstractPlatform; bin_path::Abstr
             write_wrapper(rustc, p, "$(t)-rustc")
             write_wrapper(rustup, p, "$(t)-rustup")
             write_wrapper(cargo, p, "$(t)-cargo")
-
-            # For FreeBSD and macOS we need to create an unversioned link for
-            # gcc because that's the linker our Rust toolchain expects:
-            # https://github.com/JuliaPackaging/Yggdrasil/blob/fff0583bc2d8f32e450c427684f295524f38535d/0_RootFS/Rust/build_tarballs.jl#L115-L126.
-            if Sys.isbsd(p) && os_version(p) !== nothing
-                tmp_p = deepcopy(p)
-                delete!(tags(tmp_p), "os_version")
-                symlink("$(t)-gcc", joinpath(bin_path, triplet(p), "$(aatriplet(tmp_p))-gcc"))
-            end
-            # Currently our Rust toolchain expects the linker for armv7l and
-            # armv6l with the platform "*l" suffix in the platform.  Until
-            # https://github.com/JuliaPackaging/Yggdrasil/pull/2168 makes it to
-            # the Rust toolchain, we create a symlink to work around this issue.
-            if proc_family(p) == "arm" && nbits(p) == 32
-                symlink("$(t)-gcc", joinpath(bin_path, triplet(p), "$(triplet(abi_agnostic(p)))-gcc"))
-            end
         end
     end
 

src/UserNSRunner.jl

@@ -58,7 +58,7 @@ function UserNSRunner(workspace_root::String;
         # Generate directory where to write Cargo config files
         if isone(length(collect(compilers))) && :rust in collect(compilers)[1].second
             cargo_dir = mktempdir()
-            cargo_config_file!(cargo_dir)
+            cargo_config_file!(cargo_dir, platform)
             # Add to the list of mappings a subdirectory of ${CARGO_HOME}, whose content
             # will be put in ${CARGO_HOME}.
             push!(mappings, cargo_dir => envs["CARGO_HOME"] * "/" * randstring())