refactor(resolve): Abstract out MSRV policy tracking

Author: epage

src/cargo/core/workspace.rs

@@ -605,6 +605,10 @@ impl<'gctx> Workspace<'gctx> {
         self.members().filter_map(|pkg| pkg.rust_version()).min()
     }
 
+    pub fn resolve_honors_rust_version(&self) -> bool {
+        self.gctx().cli_unstable().msrv_policy
+    }
+
     pub fn custom_metadata(&self) -> Option<&toml::Value> {
         self.custom_metadata.as_ref()
     }

src/cargo/ops/resolve.rs

@@ -323,7 +323,7 @@ pub fn resolve_with_previous<'gctx>(
     if ws.gctx().cli_unstable().minimal_versions {
         version_prefs.version_ordering(VersionOrdering::MinimumVersionsFirst)
     }
-    if ws.gctx().cli_unstable().msrv_policy {
+    if ws.resolve_honors_rust_version() {
         version_prefs.max_rust_version(ws.rust_version().cloned().map(RustVersion::into_partial));
     }