Add a toolchain check to enforce compiler version

Author: nyonson

ci/run_task.sh

@@ -86,34 +86,41 @@ main() {
 
     case $task in
     stable)
+        need_toolchain "stable"
         # Test, run examples, do feature matrix.
         # crate/contrib/test_vars.sh is sourced in this function.
         build_and_test
         ;;
 
     nightly)
+        need_toolchain "nightly"
         build_and_test
         ;;
 
     msrv)
+        need_toolchain "msrv"
         build_and_test
         ;;
 
     lint)
+        need_toolchain "nightly"
         do_lint_workspace
         do_lint_crates
         do_dup_deps
         ;;
 
     docs)
+        need_toolchain "stable"
         build_docs_with_stable_toolchain
         ;;
 
     docsrs)
+        need_toolchain "nightly"
         build_docs_with_nightly_toolchain
         ;;
 
     bench)
+        need_toolchain "nightly"
         do_bench
         ;;
 
@@ -243,14 +250,12 @@ loop_features() {
 
 # Lint the workspace.
 do_lint_workspace() {
-    need_nightly
     $cargo clippy --workspace --all-targets --all-features --keep-going -- -D warnings
     $cargo clippy --workspace --all-targets --keep-going -- -D warnings
 }
 
 # Run extra crate specific lints, e.g. clippy with no-default-features.
 do_lint_crates() {
-    need_nightly
     for crate in $CRATES; do
         pushd "$REPO_DIR/$crate" > /dev/null
         if [ -e ./contrib/extra_lints.sh ]; then
@@ -307,7 +312,6 @@ do_dup_deps() {
 # Build the docs with a nightly toolchain, in unison with the function
 # below this checks that we feature guarded docs imports correctly.
 build_docs_with_nightly_toolchain() {
-    need_nightly
     # -j1 is because docs build fails if multiple versions of `bitcoin_hashes` are present in dep tree.
     RUSTDOCFLAGS="--cfg docsrs -D warnings -D rustdoc::broken-intra-doc-links" $cargo doc --all-features -j1
 }
@@ -367,11 +371,41 @@ need_cmd() {
     fi
 }
 
-need_nightly() {
-    cargo_ver=$(cargo --version)
-    if echo "$cargo_ver" | grep -q -v nightly; then
-        err "Need a nightly compiler; have $(cargo --version)"
-    fi
+# Check that we have the required toolchain.
+need_toolchain() {
+    local required_toolchain="$1"
+    local current_toolchain
+    current_toolchain=$(rustc --version)
+    
+    case "$required_toolchain" in
+        nightly)
+            if ! echo "$current_toolchain" | grep -q nightly; then
+                err "Need a nightly compiler; have $current_toolchain"
+            fi
+            ;;
+        stable)
+            if echo "$current_toolchain" | grep -q nightly || echo "$current_toolchain" | grep -q beta; then
+                err "Need a stable compiler; have $current_toolchain"
+            fi
+            ;;
+        msrv)
+            # Get MSRV from cargo metadata, assume a workspace has a consistent MSRV for all crates and just grab the first one.
+            local msrv_version
+            msrv_version=$(cargo metadata --format-version 1 --no-deps | jq -r '.packages[] | .rust_version // empty' | grep -v '^$' | head -1)
+            if [ -z "$msrv_version" ]; then
+                err "No MSRV specified in Cargo.toml; cannot validate MSRV toolchain"
+            fi
+            
+            local current_version
+            current_version=$(echo "$current_toolchain" | grep -o '[0-9]\+\.[0-9]\+\.[0-9]\+' | head -1)
+            if [ "$current_version" != "$msrv_version" ]; then
+                err "Need Rust $msrv_version for MSRV testing; have $current_version"
+            fi
+            ;;
+        *)
+            err "Unknown toolchain requirement: $required_toolchain"
+            ;;
+    esac
 }
 
 #