Stops reporting identical objects as being different (#5934)

**What's the problem this PR addresses?**

The constraints engine is making a `===` check, so using the `set`
method with a JS object will never match and will report an error
(example
[here](https://github.com/babel/babel/actions/runs/6711592648/job/18239331717?pr=16069#step:4:8)).

**How did you fix it?**

We now compare stringified values to check sameness. I considered using
something like `_.equals`, but using stringify only returns `true` when
the key are in the same order, which is important for fields like
`exports`.

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.yarn/versions/68e485e1.yml

@@ -0,0 +1,23 @@
+releases:
+  "@yarnpkg/cli": patch
+  "@yarnpkg/plugin-constraints": patch
+
+declined:
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-essentials"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-nm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-patch"
+  - "@yarnpkg/plugin-pnp"
+  - "@yarnpkg/plugin-pnpm"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - "@yarnpkg/builder"
+  - "@yarnpkg/core"
+  - "@yarnpkg/doctor"

packages/acceptance-tests/pkg-tests-specs/sources/commands/constraints.test.ts

@@ -107,6 +107,39 @@ describe(`Commands`, () => {
       await expect(run(`constraints`)).rejects.toThrow(/This should fail/);
     }));
 
+    it(`shouldn't report errors when comparing identical objects`, makeTemporaryEnv({
+      foo: {
+        ok: true,
+      },
+    }, async ({path, run, source}) => {
+      await run(`install`);
+
+      await writeFile(ppath.join(path, `yarn.config.cjs`), `
+        exports.constraints = ({Yarn}) => {
+          Yarn.workspace().set('foo', {ok: true});
+        };
+      `);
+
+      await run(`constraints`);
+    }));
+
+    it(`should report an error when comparing objects with different key ordering`, makeTemporaryEnv({
+      foo: {
+        b: true,
+        a: true,
+      },
+    }, async ({path, run, source}) => {
+      await run(`install`);
+
+      await writeFile(ppath.join(path, `yarn.config.cjs`), `
+        exports.constraints = ({Yarn}) => {
+          Yarn.workspace().set('foo', {a: true, b: true});
+        };
+      `);
+
+      await expect(run(`constraints`)).rejects.toThrow(`Invalid field foo; expected { a: true, b: true }, found { b: true, a: true }`);
+    }));
+
     for (const [environmentDescription, environment] of Object.entries(environments)) {
       for (const [scriptDescription, scripts] of Object.entries(constraints)) {
         for (const [scriptType, script] of Object.entries(scripts)) {

packages/plugin-constraints/sources/constraintUtils.ts

@@ -203,7 +203,7 @@ export function applyEngineReport(project: Project, {manifestUpdates, reportedEr
         const [[newValue]] = newValues;
 
         const currentValue = get(manifest, fieldPath);
-        if (currentValue === newValue)
+        if (JSON.stringify(currentValue) === JSON.stringify(newValue))
           continue;
 
         if (!fix) {