Default and export naming fixes #2001

guybedford · 2018-02-21T13:29:07Z

This fixes #1996 along with some other cases around export default and named exports:

The issue was the fact that default exports get a temporary reassignment tracking variable. So the fix was to ensure this variable supports safeName and doesn't get a safe name when there's an original reassignment.
There was an issue with the CJS and AMD export mode on chunks being set to auto. Internal chunks need to always use named exports for consistency with the interfaces, which fixed a missed test case as well.
ensureExport now takes an export name argument. Export names can in theory be arbitrary, but when they match up with the exact signature of a chunk we allow chunks to become entry point chunks. So ensuring export name consistency helps ensure we don't create unnecessary facades.
Removed an unused code path in ensureExport
Default exports are now called default by default, while we were using their import aliases before.

The depths of these cases keeps expanding... I'm sure it will continue to! But as long as we put equal effort into refactoring and fixes we should be on a good footing (and project sponsorship has been a huge help to justify this time input!!).

anandthakker · 2018-02-21T17:29:11Z

@guybedford Tried this out over in mapbox/mapbox-gl-js#6196 and I'm seeing:

exports.* = commonjsGlobal;
exports.*$1 = unwrapExports;
exports.*$2 = createCommonjsModule;

in chunk1.js

anandthakker · 2018-02-21T17:44:23Z

src/ast/variables/ExportDefaultVariable.ts

@@ -14,6 +14,7 @@ export default class ExportDefaultVariable extends LocalVariable {
 		super(name, exportDefaultDeclaration, exportDefaultDeclaration.declaration);
 		this.isDefault = true;
 		this.hasId = !!(<FunctionDeclaration | ClassDeclaration>exportDefaultDeclaration.declaration).id;
+		this.exportName = 'default';


How hard would it be to include the filename of the module as part of this name, e.g., my_module$default for the default export of my-module.js? Seems like this could make for easier debugging in some cases.

The reason we use the initial name is because this stage of the algorithm is still attempting to determine if the chunk is an entry point module itself (entry.js), or if it is a chunk (chunk[i].js). Ideally the algorithm could do the export naming after this stage in the process in which case we can better handle naming definitely. I will look into a refactor along these lines, but perhaps not just yet.

(So basically in the scenario that the chunk is an entry point, we need it to do the correct naming as the entry point would expect)

anandthakker · 2018-02-21T19:02:16Z

diff --git a/src/Chunk.ts b/src/Chunk.ts
index 6c01905c..69b6eea4 100644
--- a/src/Chunk.ts
+++ b/src/Chunk.ts
@@ -146,9 +146,10 @@ export default class Chunk {
                }

                let i = 0;
-               safeExportName = exportName;
+               const baseExportName = exportName === '*' ? '_namespace' : exportName;
+               safeExportName = baseExportName;
                while (this.exports[safeExportName]) {
-                       safeExportName = exportName + '$' + ++i;
+                       safeExportName = baseExportName + '$' + ++i;
                }
                variable.exportName = safeExportName;

Fixes the above for me

guybedford · 2018-02-21T20:06:12Z

@anandthakker any chance of a test case? I take it you have a namespace import across a chunk boundary?

anandthakker · 2018-02-21T20:11:12Z

@guybedford y, I'll try to reduce a test case. We don't have an explicit namespace import -- from the variable names (commonjsGlobal, unwrapExports, createCommonjsModule), my guess is that this is coming from a module produced by https://github.com/rollup/rollup-plugin-commonjs

guybedford · 2018-02-21T20:15:39Z

Sure no stress, I'll run it on my test case here for that too and see what I can find.

anandthakker · 2018-02-21T20:41:13Z

@guybedford reduced test case here: https://gist.github.com/anandthakker/68b1b63f2c1236e85709aae0f9f80ad9

guybedford · 2018-02-21T21:10:10Z

@anandthakker amazing thanks for isolating - my CJS case here didn't catch it.

guybedford · 2018-02-21T21:47:59Z

@anandthakker I've included the fix here. Thanks again for the test cases.

anandthakker · 2018-02-22T02:25:02Z

@guybedford thanks! Confirmed that it's working in practice over at https://github.com/mapbox/mapbox-gl-js/tree/6fa5becea62ac5a58a5eb1572fb764c64e50fa36

anandthakker · 2018-02-22T02:26:28Z

(By the way, @guybedford, you can also see there the hacky way we're using code splitting to approximate the new Worker() strategy under discussion over at #1029)

lukastaegert

Great work!

lukastaegert · 2018-02-22T06:43:24Z

src/Chunk.ts

@@ -115,6 +115,8 @@ export default class Chunk {
 		this.dependencies = undefined;
 		this.entryModule = undefined;
 		this.isEntryModuleFacade = false;
+		if (orderedModules.length === 0)
+			this.isEntryModuleFacade = true;


This would easily merge with the previous assignment.

lukastaegert · 2018-02-22T06:46:07Z

src/Chunk.ts

@@ -136,44 +138,30 @@ export default class Chunk {
 	// ensure that the module exports or reexports the given variable
 	// we don't replace reexports with the direct reexport from the final module
 	// as this might result in exposing an internal module which taints an entryModule chunk
-	ensureExport (module: Module | ExternalModule, variable: Variable): string {
+	ensureExport (module: Module | ExternalModule, variable: Variable, exportName: string): string {
+		// assert(module.chunk === this || module.isExternal);
 		let safeExportName = this.exportedVariables.get(variable);


Maybe we should actually call this this.exportedVariableNames to make clear what we are mapping the variables to.

lukastaegert · 2018-02-22T07:01:15Z

src/Chunk.ts

-		else {
-			curExport.name = safeExportName;
-		}
-
 		return safeExportName;
 	}


lukastaegert · 2018-02-22T07:18:06Z

src/ast/scopes/Scope.ts

@@ -86,7 +86,7 @@ export default class Scope {
 			const declaration = this.variables[key];

 			// we can disregard exports.foo etc
-			if (declaration.exportName && declaration.isReassigned && !declaration.isId)
+			if (declaration.exportName && (declaration.isDefault || declaration.isReassigned && !declaration.isId))


The non-use of more parentheses here makes me a little uneasy (sorry, but I'm one of those people who need to look into an operator precedence table to see that && binds more strongly than ||).

lukastaegert

Awesome! I also very much like the additional private modifiers that will help us keep the API surface small.

arackaf · 2018-02-24T16:17:06Z

I'm trying to test this branch out, but I can't quite get npm to install it - can anyone here possibly lend a hand? As far as I can tell, this is what I want

npm i https://github.com/rollup/rollup.git#default-identifier-renaming --save

but npm doesn't seem to like it (nor plenty of the variations on that theme which I've also tried)

This seems to fail too :(

npm i rollup/rollup#default-identifier-renaming --save

lukastaegert · 2018-02-25T18:28:53Z

Hi @arackaf,

you should probably check your npm version. As rollup relies on its prepare script being executed to build its bundle, direct Github installation will only work for npm versions 5.0.0 and later. As I just confirmed, npm i rollup/rollup#default-identifier-renaming --save should work with current npm versions.

Nevertheless, I am about to release this branch now anyway 😉

arackaf · 2018-02-25T19:05:33Z

Aha! Thanks Lukas. I'm still too scared to go back in the npm 5 waters. I reverted back to the comfort and safety of npm 4 since many of the 5 bugs affected me directly.

guybedford · 2018-02-25T19:28:53Z

@arackaf for future reference try git://github.com/rollup/rollup#default-identifier-renaming.

lukastaegert · 2018-02-26T07:31:42Z

@arackaf Might be worth giving npm@5 another shot. A lot has been fixed and improved since 5.0.0. We're using it at work for two large projects and after some initial hickups, it's now been smooth riding for quite a few months now. The performance benefits are nothing to sneeze at 😉

default and export naming fixes

68366d8

This was referenced Feb 21, 2018

Code splitting with 'amd' output with default export from common chunk causes incorrect import from dependent chunks #1996

Closed

failing test for default export renames #1991

Closed

guybedford requested a review from lukastaegert February 21, 2018 13:34

anandthakker reviewed Feb 21, 2018

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anandthakker mentioned this pull request Feb 21, 2018

Switch to ES modules and Rollup mapbox/mapbox-gl-js#6196

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guybedford mentioned this pull request Feb 21, 2018

Chunking appears to separate variable definition from usage #1989

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fix namespace resolution cases on chunk boundaries

58cfc47

lukastaegert added this to the 0.56.3 milestone Feb 22, 2018

lukastaegert approved these changes Feb 22, 2018

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db17e0f

lukastaegert approved these changes Feb 23, 2018

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lukastaegert merged commit db17e0f into master Feb 25, 2018

lukastaegert deleted the default-identifier-renaming branch February 25, 2018 18:32

dependabot-preview bot mentioned this pull request Mar 15, 2018

Update rollup requirement to ^0.57.0 stephenreynolds/screeps#74

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commonjs module exports arantes555/electron-fetch#7

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Default and export naming fixes #2001

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Default and export naming fixes #2001

Default and export naming fixes #2001

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