Allow specifying a Rust toolchain version for the build

Author: imciner2

src/Rootfs.jl

@@ -576,7 +576,7 @@ function choose_shards(p::AbstractPlatform;
             ps_build::VersionNumber=v"2024.08.10",
             GCC_builds::Vector{GCCBuild}=available_gcc_builds,
             LLVM_builds::Vector{LLVMBuild}=available_llvm_builds,
-            Rust_build::VersionNumber=maximum(getversion.(available_rust_builds)),
+            Rust_builds::Vector{RustBuild}=available_rust_builds,
             Go_build::VersionNumber=maximum(getversion.(available_go_builds)),
             archive_type::Symbol = (use_squashfs[] ? :squashfs : :unpacked),
             bootstrap_list::Vector{Symbol} = bootstrap_list,
@@ -586,6 +586,9 @@ function choose_shards(p::AbstractPlatform;
             # Because LLVM doesn't have compatibility issues, we always default
             # to the newest version possible.
             preferred_llvm_version::VersionNumber = getversion(LLVM_builds[end]),
+            # Rust can have compatibility issues between versions, but by default choose
+            # the newest one.
+            preferred_rust_version::VersionNumber = maximum(getversion.(Rust_builds)),
         )
 
     function find_shard(name, version, archive_type; target = nothing)
@@ -654,6 +657,13 @@ function choose_shards(p::AbstractPlatform;
         end
 
         if :rust in compilers
+            # Make sure the selected Rust toolchain version is available
+            if preferred_rust_version in getversion.(Rust_builds)
+                Rust_build = preferred_rust_version
+            else
+                error("Requested Rust toolchain $(preferred_rust_version) not available in $(Rust_builds)")
+            end
+
             append!(shards, [
                 find_shard("RustBase", Rust_build, archive_type),
                 find_shard("RustToolchain", Rust_build, archive_type; target=p),

test/rootfs.jl

@@ -1,6 +1,7 @@
 using Test
 using Base.BinaryPlatforms
 using BinaryBuilderBase
+using BinaryBuilderBase: RustBuild, CompilerShard
 
 @testset "Expand platforms" begin
     # expand_gfortran_versions
@@ -117,6 +118,17 @@ end
 @testset "Compiler Shards" begin
     @test_throws ErrorException CompilerShard("GCCBootstrap", v"4", Platform("x86_64", "linux"), :invalid_archive_type)
 
+    @testset "Rust toolchain selection" begin
+        platform = Platform("x86_64", "linux")
+        common_opts = (preferred_gcc_version=v"9", compilers=[:c, :rust])
+
+        shards = choose_shards(platform; preferred_rust_version = v"1.73", (common_opts)... )
+        @test filter(s-> s.name == "RustBase", shards)[end].version == v"1.73"
+        @test filter(s-> s.name == "RustToolchain", shards)[end].version == v"1.73"
+
+        @test_throws ErrorException choose_shards(platform; preferred_rust_version = v"1.78", (common_opts)...)
+    end
+
     @testset "GCC ABI matching" begin
         # Preferred libgfortran version and C++ string ABI
         platform = Platform("x86_64", "freebsd")