fix: issue-5850 - Settle override conflicts between edges and propagate changes

workspaces/arborist/lib/dep-valid.js

@@ -101,7 +101,7 @@ const depValid = (child, requested, requestor) => {
       })
     }
 
-    default: // unpossible, just being cautious
+    default: // impossible, just being cautious
       break
   }
 

workspaces/arborist/lib/edge.js

@@ -112,7 +112,31 @@ class Edge {
     if (node.hasShrinkwrap || node.inShrinkwrap || node.inBundle) {
       return depValid(node, this.rawSpec, this.#accept, this.#from)
     }
-    return depValid(node, this.spec, this.#accept, this.#from)
+
+    // If there's no override we just use the spec.
+    if (!this.overridden) {
+      return depValid(node, this.spec, this.#accept, this.#from)
+    }
+    // There's some override. If the target node satisfies the overriding spec
+    // then it's okay.
+    if (depValid(node, this.spec, this.#accept, this.#from)) {
+      return true
+    }
+    // If it doesn't, then it should at least satisfy the original spec.
+    if (!depValid(node, this.rawSpec, this.#accept, this.#from)) {
+      return false
+    }
+    // It satisfies the original spec, not the overriding spec. We need to make
+    // sure it doesn't use the overridden spec.
+    // For example:
+    //   we might have an ^8.0.0 rawSpec, and an override that makes
+    //   keySpec=8.23.0 and the override value spec=9.0.0.
+    //   If the node is 9.0.0, then it's okay because it's consistent with spec.
+    //   If the node is 8.24.0, then it's okay because it's consistent with the rawSpec.
+    //   If the node is 8.23.0, then it's not okay because even though it's consistent
+    //   with the rawSpec, it's also consistent with the keySpec.
+    //   So we're looking for ^8.0.0 or 9.0.0 and not 8.23.0.
+    return !depValid(node, this.overrides.keySpec, this.#accept, this.#from)
   }
 
   // return the edge data, and an explanation of how that edge came to be here

workspaces/arborist/lib/node.js

@@ -358,7 +358,7 @@ class Node {
     // versions. To make sure this package was actually overridden, we check whether any edge going in
     // had the rule applied to it, in which case its overrides set is different than its source node.
     for (const edge of this.edgesIn) {
-      if (this.overrides.isEqual(edge.overrides)) {
+      if (edge.overrides && edge.overrides.name === this.name && edge.overrides.value === this.version) {
         if (!edge.overrides.isEqual(edge.from.overrides)) {
           return true
         }