feat(ctb): spacer validation task (#3533)

Introduces a new task for validating the correctness of spacer
variables. Prevents future developers from accidentally moving spacers.
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

.circleci/config.yml

@@ -134,6 +134,10 @@ jobs:
           name: lint
           command: yarn lint:check
           working_directory: packages/contracts-bedrock
+      - run:
+          name: validate spacers
+          command: yarn validate-spacers
+          working_directory: packages/contracts-bedrock
       - run:
           name: slither
           command: |

packages/contracts-bedrock/package.json

@@ -26,6 +26,7 @@
     "coverage:lcov": "yarn build:differential && forge coverage --report lcov",
     "gas-snapshot": "yarn build:differential && forge snapshot",
     "storage-snapshot": "./scripts/storage-snapshot.sh",
+    "validate-spacers": "hardhat validate-spacers",
     "slither": "./scripts/slither.sh",
     "clean": "rm -rf ./dist ./artifacts ./forge-artifacts ./cache ./tsconfig.tsbuildinfo ./src/contract-artifacts.ts",
     "lint:ts:check": "eslint . --max-warnings=0",

packages/contracts-bedrock/tasks/index.ts

@@ -5,3 +5,4 @@ import './check-op-node'
 import './check-l2-config'
 import './watch'
 import './forge-verify'
+import './validate-spacers'

packages/contracts-bedrock/tasks/validate-spacers.ts

+import { task } from 'hardhat/config'
+
+task(
+  'validate-spacers',
+  'validates that spacer variables are in the correct positions'
+).setAction(async (args, hre) => {
+  const names = await hre.artifacts.getAllFullyQualifiedNames()
+  for (const name of names) {
+    // Script is remarkably slow because of getBuildInfo, so better to skip test files since they
+    // don't matter for this check.
+    if (name.includes('.t.sol')) {
+      continue
+    }
+
+    const buildInfo = await hre.artifacts.getBuildInfo(name)
+    for (const source of Object.values(buildInfo.output.contracts)) {
+      for (const [contractName, contract] of Object.entries(source)) {
+        const storageLayout = (contract as any).storageLayout
+        for (const variable of storageLayout?.storage || []) {
+          if (variable.label.startsWith('spacer_')) {
+            const [, slot, offset, length] = variable.label.split('_')
+
+            // Check that the slot is correct.
+            if (slot !== variable.slot) {
+              throw new Error(
+                `${contractName} ${variable.label} is in slot ${variable.slot} but should be in ${slot}`
+              )
+            }
+
+            // Check that the offset is correct.
+            if (parseInt(offset, 10) !== variable.offset) {
+              throw new Error(
+                `${contractName} ${variable.label} is at offset ${variable.offset} but should be at ${offset}`
+              )
+            }
+
+            // Figure out the length of the variable.
+            let variableLength: number
+            if (variable.type.startsWith('t_mapping')) {
+              variableLength = 32
+            } else if (variable.type.startsWith('t_uint')) {
+              variableLength = variable.type.match(/uint([0-9]+)/)?.[1] / 8
+            } else if (variable.type.startsWith('t_bytes_')) {
+              variableLength = 32
+            } else if (variable.type.startsWith('t_bytes')) {
+              variableLength = variable.type.match(/uint([0-9]+)/)?.[1]
+            } else if (variable.type.startsWith('t_address')) {
+              variableLength = 20
+            } else {
+              throw new Error('unsupported type, add it to the script')
+            }
+
+            // Check that the length is correct.
+            if (parseInt(length, 10) !== variableLength) {
+              throw new Error(
+                `${contractName} ${variable.label} is ${variableLength} bytes long but should be ${length}`
+              )
+            }
+          }
+        }
+      }
+    }
+  }
+})