Reapply "Unused Variable Warnings" (#1825) by lmulcahy21 · Pull Request #1832 · hazelgrove/hazel

lmulcahy21 · 2025-07-27T01:18:07Z

This reverts commit 2bdb606, reversing changes made to 5328152. See original PR at #1033.

This reverts commit 2bdb606, reversing changes made to 5328152.

Copilot

Pull Request Overview

This PR reapplies functionality for displaying unused variable warnings in the Hazel editor. The feature adds visual indicators and user interface elements to show warnings about unused variables, with a toggle to enable/disable warning display.

Key Changes

Adds a warnings system with visual styling to differentiate warnings from errors
Implements unused variable detection for pattern variables
Adds a user settings toggle to control warning display visibility

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/web/www/style/variables.css	Defines warning-specific CSS color variables and z-index values
src/web/www/style/editor.css	Adds styling for warning decorations with dashed borders
src/web/www/style/dynamics.css	Updates error message selector syntax
src/web/www/style/cursor-inspector.css	Styles cursor inspector warning states
src/web/view/NutMenu.re	Adds warnings toggle to developer menu
src/web/app/inspector/CursorInspector.re	Implements warning display logic in cursor inspector
src/web/app/editors/decoration/Deco.re	Adds warning decorations to editor
src/web/app/common/ProjectorView.re	Adds warning state to projector status
src/web/Settings.re	Adds display_warnings setting
src/language/statics/Warning.re	Defines warning types and unused variable detection
src/language/statics/Statics.re	Integrates warning detection into static analysis
src/language/statics/Info.re	Adds warning field to info types
src/language/statics/CoCtx.re	Adds hole detection utility
src/language/CoreSettings.re	Adds display_warnings to core settings
src/haz3lcore/derived/CachedStatics.re	Tracks warning IDs alongside error IDs

Copilot · 2025-07-30T20:26:36Z

src/web/www/style/dynamics.css

 }

-.cell-item.cell-result .error-msg {
+.cell-item.cell-result .error-msg .warning-msg {


The CSS selector is malformed. It should use a comma to separate selectors for both error and warning messages: .cell-item.cell-result .error-msg, .cell-item.cell-result .warning-msg {

Suggested change

.cell-item.cell-result .error-msg .warning-msg {

.cell-item.cell-result .error-msg, .cell-item.cell-result .warning-msg {

Copilot · 2025-07-30T20:26:37Z

src/language/statics/Statics.re

      let e_co_ctxs =
-        List.map2(CoCtx.mk(ctx), p_ctxs, List.map(Info.exp_co_ctx, es));
+        List.map2(
+          ((p_ctx, _ctx)) => CoCtx.mk(p_ctx, p_ctx),


The CoCtx.mk call uses p_ctx for both arguments, but the original code used ctx for the first argument. This change may affect context handling incorrectly.

Suggested change

((p_ctx, _ctx)) => CoCtx.mk(p_ctx, p_ctx),

((p_ctx, _ctx)) => CoCtx.mk(p_ctx, ctx),

I've been scrutinizing these changes flagged by Copilot and am confused. Commenting them out makes unused variable warnings appear even when they are used.

But I don't understand why it would make sense to pass in p_ctx for both ctx_before and ctx_after args to CoCtx.mk. Separately, seems weird to zip together the constant ctx with all the p_ctxs only to ignore it later, assuming that isn't needed at all. Finally, while I don't follow why this change makes sense, I'm pretty sure this would mess up the co-ctx calculation for the overall case expression.

Copilot

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codecov · 2025-12-02T21:01:53Z

Codecov Report

❌ Patch coverage is 50.81967% with 30 lines in your changes missing coverage. Please review.
✅ Project coverage is 50.09%. Comparing base (c5711fb) to head (2c4015e).

Files with missing lines	Patch %	Lines
src/web/app/editors/decoration/Arms.re	0.00%	7 Missing ⚠️
src/language/statics/Info.re	68.75%	5 Missing ⚠️
src/language/statics/Warning.re	44.44%	5 Missing ⚠️
src/haz3lcore/projectors/ProjectorBase.re	0.00%	2 Missing ⚠️
src/language/statics/StaticsBase.re	50.00%	2 Missing ⚠️
src/web/Settings.re	0.00%	2 Missing ⚠️
src/web/app/common/ProjectorView.re	0.00%	2 Missing ⚠️
src/web/app/editors/code/CodeWithStatics.re	0.00%	2 Missing ⚠️
src/haz3lcore/derived/CachedStatics.re	50.00%	1 Missing ⚠️
src/language/CoreSettings.re	0.00%	1 Missing ⚠️
... and 1 more

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1832      +/-   ##
==========================================
- Coverage   50.09%   50.09%   -0.01%     
==========================================
  Files         232      233       +1     
  Lines       25567    25617      +50     
==========================================
+ Hits        12807    12832      +25     
- Misses      12760    12785      +25

Files with missing lines	Coverage Δ
src/language/statics/CoCtx.re	`54.16% <100.00%> (+1.99%)`	⬆️
src/web/view/NutMenu.re	`0.00% <ø> (ø)`
src/haz3lcore/derived/CachedStatics.re	`34.78% <50.00%> (+0.69%)`	⬆️
src/language/CoreSettings.re	`0.00% <0.00%> (ø)`
src/language/statics/Statics.re	`86.88% <92.30%> (+<0.01%)`	⬆️
src/haz3lcore/projectors/ProjectorBase.re	`5.88% <0.00%> (-0.12%)`	⬇️
src/language/statics/StaticsBase.re	`45.94% <50.00%> (+0.23%)`	⬆️
src/web/Settings.re	`0.00% <0.00%> (ø)`
src/web/app/common/ProjectorView.re	`0.00% <0.00%> (ø)`
src/web/app/editors/code/CodeWithStatics.re	`33.33% <0.00%> (-1.81%)`	⬇️
... and 3 more

... and 11 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

dm0n3y · 2025-12-03T20:06:55Z

@cyrus- @disconcision fixed merge conflicts, seems to work as expected

Resolve merge conflicts keeping both warning support and dev features (targets/sampling, meta-down, line numbers, selected-expanded styles). Co-Authored-By: Claude Opus 4.6 <[email protected]>

dm0n3y · 2026-02-17T18:03:35Z

@cyrus- thoughts here? #1832 (comment)

dm0n3y · 2026-02-19T16:21:15Z

@cyrus- thoughts here? #1832 (comment)

resolved by fbc97a8

dm0n3y · 2026-02-23T17:07:45Z

@cyrus- this should be good to go

cyrus-

turn on warnings by default
leave a hole at the bottom of the doc slides so unused variables aren't shown
add a section to the doc slides describing how unused variables work (underscore prefix, doesn't show up if there is a hole in the scope of the variable)

lmulcahy21 and others added 2 commits July 26, 2025 18:17

Reapply "Unused Variable Warnings" (#1825)

b2f7f46

This reverts commit 2bdb606, reversing changes made to 5328152.

Merge branch 'dev' into unused-var-warnings-2

ea4320d

disconcision requested a review from Copilot July 30, 2025 20:26

cyrus- requested a review from Copilot July 30, 2025 20:26

Copilot AI reviewed Jul 30, 2025

View reviewed changes

Merge branch 'dev' into unused-var-warnings-2

e93c02d

fix broken classes + selectors

f26f094

dm0n3y and others added 2 commits February 13, 2026 12:37

Merge branch 'dev' into unused-var-warnings-2

8dc0654

Resolve merge conflicts keeping both warning support and dev features (targets/sampling, meta-down, line numbers, selected-expanded styles). Co-Authored-By: Claude Opus 4.6 <[email protected]>

don't show warning decos when setting toggle is off

f318dfb

cyrus- and others added 4 commits February 17, 2026 16:30

Merge branch 'dev' into unused-var-warnings-2

38eede2

rm unused malformed selector

c77f0eb

separate co-ctx calculations for inside and outside case clauses

fbc97a8

add tests

b46ea0c

dm0n3y added 4 commits February 19, 2026 14:09

tweak hack

560d619

revert unrelated change

2d86305

prioritize showing error decos over warning decos

cfb1898

rm unused code

e2c197d

cyrus- requested changes Feb 24, 2026

View reviewed changes

Merge branch 'dev' into unused-var-warnings-2

2c4015e

Provide feedback

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Reapply "Unused Variable Warnings" (#1825)#1832

Reapply "Unused Variable Warnings" (#1825)#1832
lmulcahy21 wants to merge 15 commits intodevfrom
unused-var-warnings-2

lmulcahy21 commented Jul 27, 2025

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	.cell-item.cell-result .error-msg .warning-msg {
	.cell-item.cell-result .error-msg, .cell-item.cell-result .warning-msg {

	((p_ctx, _ctx)) => CoCtx.mk(p_ctx, p_ctx),
	((p_ctx, _ctx)) => CoCtx.mk(p_ctx, ctx),

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Pull Request Overview

Key Changes

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codecov bot commented Dec 2, 2025 •

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