ng cli build --prod fails when activating noUnusedParameters in tsconfig.json

[reppners]

Bug, feature request, or proposal:

Bug/Improvement

What is the expected behavior?

Should be able to build with ng build --prod when having compilerOptions.noUnusedParameters: true in tsconfig.json

What is the current behavior?

Build fails with

ERROR in my-project/src/$$_gendir/node_modules/@angular/material/typings/index.ngfactory.ts (2252,41): 'l' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdButton.html (8,1): 'v' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdAnchor.html (8,1): 'v' is declared but never used.

ERROR in my-project/src/$$_gendir/node_modules/@angular/material/typings/index.ngfactory.ts (3345,31): 'l' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdInputContainer_Host.html (2,1): '$event' is declared but never used.

ERROR in my-project/src/$$_gendir/node_modules/@angular/material/typings/index.ngfactory.ts (4539,31): 'l' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdListItem_Host.html (2,1): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdSelect.html (23,5): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdSelect.html (2,1): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdSelect.html (15,7): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdSidenavContainer.html (2,1): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdTabGroup.html (5,3): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdTabHeader.html (2,1): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdTabHeader.html (12,3): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdTabHeader.html (20,1): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdButtonToggle.html (17,1): 'v' is declared but never used.

ERROR in my-project/src/$$_gendir/node_modules/@angular/material/typings/index.ngfactory.ts (7426,31): 'l' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.MdSlideToggle_Host.html (2,1): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.SimpleSnackBar.html (3,1): '$event' is declared but never used.

ERROR in my-project/node_modules/@angular/material/typings/index.d.ts.TooltipComponent_Host.html (2,1): '$event' is declared but never used.

What are the steps to reproduce?

• create fresh project ng new my-project
• install and include @angular/material as per the docs
• set "noUnusedParameters": true in the projects tsconfig.json
• run ng build --prod

What is the use-case or motivation for changing an existing behavior?

Apps using material should be able to compile with noUnusedParameters: true in tsconfig.json.

Which versions of Angular, Material, OS, browsers are affected?

"@angular/animations": "^4.1.0",
"@angular/common": "^4.0.0",
"@angular/compiler": "^4.0.0",
"@angular/core": "^4.0.0",
"@angular/material": "^2.0.0-beta.3",
"@angular/cli": "1.0.1",

Is there anything else we should know?

Looks like this is some generated code from html templates. I don't know if it's even the fault of angular material.

The fix would be to define parameters with a leading _. See microsoft/TypeScript#9860.

[devversion]

Yeah at some point when TSlint deprecated the no-unused-variable rule I tried to use that option too.

Unfortunately the compiler option doesn't seem to be very smart and flexible, so I didn't move ahead with that.

In theory we could prefix all those variables with an underscore, but I'm not sure if TypeScript improves their option at some point & if it's worth the efforts.

[reppners]

Seems like the unused parameter issue also got some attention in the angular core recently angular/angular#15532

Would this solve this issue also or is it just fixing the index.ngfactory.ts?

[devversion]

@jelbourn Are you thinking we should prefix those variables with an underscore? And probably compile the AOT demo-app with noUnusedParameters and noUnusedLocals.

If I recall correctly there will be a lot of locals and parameters that need to be prefixed with an underscore.

[jelbourn]

1. There's nothing we can do about unused parameters in the generated code; that's all on Angular
2. If we have any unused parameters in our own source, we should just remove them.

Other than those two categories I don't think anything should change.

[devversion]

If we enable noUnusedParameters Material shows a lot of errors for stuff like that:

// Value is not used. Needs to be prefixed
_onChange = (value: any) => {};

/**
 * Sets the vertical placement of the tile in the list.
 * This method will be implemented by each type of TileStyler.
 * @docs-private
 */
setRowStyles(tile: MdGridTile, rowIndex: number, percentWidth: number, gutterWidth: number) {}

The setRowStyles function is not implemented and is kind of "abstract" (but other functions are implemented).

TypeScript would force us to prefix them with an underscore. Not a big deal, but just want to let you know what will change.

[jelbourn]

Function params should not be prefixed with an underscore.

If a method is abstract, it should be marked as abstract.

For that onChange, it should be

_onChange: (any?) => void = () => {};

[devversion]

Yeah that makes sense. I didn't write the grid-list so I don't know why it isn't made abstract.

Most of those noUnusedParameters failures can be fixed easily. But I think we need a way to check this on the CI (once we fixed all of those)

[jelbourn]

Yeah, if the generated code doesn't have an issue then a CI check would be necessary.

[wulfsberg]

I think this is considerably more than a "nice to have". A library like Material should not block people from using strict compiler checks in their projects.

[jelbourn]

That priority level mainly comes from the fact that Angular's generated code is the culprit in most cases, which is outside the scope of material.