[NullVoxPopuli-ai-agent]

Fixes #116. This replaces #117. GitHub closed #117 when #120 merged, because #117 used the #120 branch as its base and that branch was deleted.

A bundler that inlines constants (for example, rolldown with its default optimization.inlineConst) can rewrite a published module from

import { EMPTY } from './constants.js';
precompileTemplate('{{EMPTY}}', { strictMode: true, scope: () => ({ EMPTY }) });

to

precompileTemplate('{{EMPTY}}', { strictMode: true, scope: () => ({ EMPTY: "—" }) });

On main (4.0.1), parseScope rejects this in the consuming app with "Scope objects for precompileTemplate may only contain direct references to in-scope values … Found StringLiteral".

What #120 fixed, and what this PR adds

#116 has two parts:

1. Scope object keys were renamed together with their values. When the compiler emits the scope as an object, { Foo: Setup } became { Setup }, and the template lost the name Foo. Don't remap scope locals in non-reference positions #120 fixed this and shipped in 4.0.1.
2. parseScope accepts only identifiers and this as scope values. A literal value that a bundler substitutes still fails the build. This PR fixes that part.

Part 1 is necessary for part 2. A value only works if its key stays the template name.

Changes

The explicit form now accepts any expression as a scope value, not only an identifier or this.

An earlier version of this PR accepted only the constant shapes that bundlers and minifiers emit: -1, void 0, !0, `—` and so on. That allow-list was most of the diff, and each new minifier shape needed another case. Any expression covers all of them with less code.

• parseScope passes every expression to ScopeLocals. Only destructuring patterns are rejected.
• ScopeLocals maps each template name to a t.Expression. A reference is an Identifier, and this is a ThisExpression. The parser, buildScope and the remap each have one path for all values.
• For the wire format, the compiler output gets a copy of the expression in place of the identifier: scope: () => ({ EMPTY: "—" }).
• For targetFormat: 'hbs', buildScope writes the expression back into the scope object, so a later wire compile accepts the output again.
• The remap skips each replacement. Its names are JS names, not hbs names. Without the skip, { a: f(a) } overflows the stack.

Two behaviors to know about:

• Unused entries are pruned, as before for identifiers. An unused { x: track() } is removed, so its side effect does not happen.
• The plugin writes its own arrow function for the scope. If the source scope is a function or a method, this and arguments inside a value can change meaning. This was already true for { foo: this }.

#126 fixes a related bug that main has for plain renames ({ a: b, b: c } and { a: b, b: a }). The skip in this PR fixes that bug too, because a rename is now one more expression replacement. #126 has the tests for it.

Tests

The new tests cover:

• the constant shapes that bundlers and minifiers emit, plus null and BigInt values
• other expressions: a call, a template literal with an expression, a regex, -foo, and a member expression
• no remap inside a copied expression
• an import that only a scope expression uses, with @babel/plugin-transform-typescript
• pruning of an unused expression
• references and literals in one scope, with an unused entry between them, so each name keeps its value in the array form
• a literal value that has the same name as a JS binding
• the explicit form of template() from @ember/template-compiler, in both target formats

The wireScope() test helper named array-form entries in locals order. The compiler orders them by first use in the template, so the helper now reads the names from the compiler output.

All 140 tests pass on the default ember-source and on 6.4. On 5.12 and 3.28 with NO_LEXICAL_THIS=true, 136 pass and 4 are skipped. tsc --noEmit and pnpm lint also pass.

With the earlier literal-only version, I also checked the build in ember.js main (all browser tests pass) and in a new app from ember-cli new. In the app, an addon dist file with inlined constants builds and renders. With 4.0.1, the same app fails to build. I did not repeat these two checks for this version.

🤖 Generated with Claude Code

[NullVoxPopuli]

Demo:

• Patch babel-plugin-ember-template-compilation to accept any scope expression NullVoxPopuli/limber#2293
• https://nvp-literal-scope-values-pat.limber-glimdown.pages.dev/edit?c=JYWwDg9gTgLgBAbzjApuANgQ1XAvnAMyghDgHIABNAIxSgHpUNsUBaAYxLGHTrIG4AUIJQAPSLDgATFAUwBXdPCZgsqABQADQXDgAeMFBRwAzjACevALwAiAhAB2MAFxwQjiCbCZ2KGwD4dXX1OGUDg4IA3CGApOAAGV0QEAFVcXCCIgEJ4iKSEBAAVdMzgrIBGPN0CgDESiN0yVjJg-IQAZXqGh0V0XTaAORSAGS6I8viHVuqEACEASQBxMeDWCam4QYBRRYB9BeWMiL16UJRw-XpDc80AGkQgsyhgdhgAWQgZVxgoeRRbx6cMAoVzqACUcCs-jg6iQpRSrmisQS91KhVcOVRERqGPKWOC7VcmkAKAR3OClIbDVw9dDofG6A6udb0uADHb7JauNaTcm6XBggH8oQNOBAA&format=gjs&shadowdom=on

input

import { template } from '@ember/template-compiler';

export default template(`
  <pre>
    void 0:{{U}}
    !0:    {{T}}
    !1:    {{F}}
    '-':   {{S}}
    null:  {{NUL}}
    10n:   {{BIG}}
    -10n:  {{NEG_BIG}}
  </pre>`, {
  strictMode: true,
  scope: () => ({ 
    U: void 0, 
    T: !0, 
    F: !1, 
    S: `—`, 
    NUL: null, 
    BIG: 10n, 
    NEG_BIG: -10n 
  }),
});
      

output

import { setComponentTemplate } from /*"@ember/component"*/'blob:https://nvp-literal-scope-values-pat.limber-glimdown.pages.dev/9e5ef27b-b1f9-4013-a23f-4f87dd8a85f5';
import { createTemplateFactory } from /*"@ember/template-factory"*/'blob:https://nvp-literal-scope-values-pat.limber-glimdown.pages.dev/b59faa1f-e57d-48ee-8ddc-9f8eacc45b77';
import templateOnly from /*"@ember/component/template-only"*/'blob:https://nvp-literal-scope-values-pat.limber-glimdown.pages.dev/91637849-7312-462b-bdae-6a7b825a90e3';
export default setComponentTemplate(createTemplateFactory(
/*
  
  <pre>
    void 0:{{U}}
    !0:    {{T}}
    !1:    {{F}}
    '-':   {{S}}
    null:  {{NUL}}
    10n:   {{BIG}}
    -10n:  {{NEG_BIG}}
  </pre>
*/
{
  "id": null,
  "block": "[[[1,\"\\n  \"],[10,\"pre\"],[12],[1,\"    void 0:\"],[1,[32,0]],[1,\"    !0:    \"],[1,[32,1]],[1,\"    !1:    \"],[1,[32,2]],[1,\"    '-':   \"],[1,[32,3]],[1,\"    null:  \"],[1,[32,4]],[1,\"    10n:   \"],[1,[32,5]],[1,\"    -10n:  \"],[1,[32,6]],[1,\"  \"],[13]],[],[]]",
  "moduleName": "(unknown template module)",
  "scope": () => ({
    U: void 0,
    T: !0,
    F: !1,
    S: `—`,
    NUL: null,
    BIG: 10n,
    NEG_BIG: -10n
  }),
  "isStrictMode": true
}), templateOnly());
//# sourceURL=file:///src/index.gjs?v=1