Fix issue with GTS transform with backtick comments by Copilot · Pull Request #227 · ember-tooling/ember-eslint-parser

Copilot · 2026-07-02T00:40:59Z

transformForLint throws bad transform for a valid GTS class template containing Glimmer comments with backtick-delimited text, even though the underlying parser accepts the template.

Regression coverage
- Adds a focused transformForLint test using the reported template shape.
- Captures the failing lint-transform path rather than the direct parser path.

export default class MyComponent extends Component {
  <template>
    {{!  `asd` `qwe` `zxc` `undefined` `asd` }}
    {{! `@foo` }}
  </template>
}

github-actions · 2026-07-02T00:50:53Z

🏎️ Benchmark Comparison

	Benchmark	Control (p50)	Experiment (p50)	Δ
🟢	gts small	1196.29 ms	1138.91 ms	-4.8%
⚪	gts medium	2151.48 ms	2189.24 ms	+1.8%
🟠	gts large	1011.05 ms	1054.96 ms	+4.3%
⚪	gjs small	962.86 ms	970.80 ms	+0.8%
🟠	gjs medium	1795.24 ms	1865.14 ms	+3.9%
⚪	gjs large	830.68 ms	828.65 ms	-0.2%
🟠	hbs small	162.82 ms	166.68 ms	+2.4%
🟠	hbs medium	936.42 ms	981.31 ms	+4.8%
🔴	hbs large	950.80 ms	1009.71 ms	+6.2%

🟢 faster · 🔴 slower · 🟠 slightly slower · ⚪ within 2%

Full mitata output

clk: ~3.11 GHz
cpu: AMD EPYC 7763 64-Core Processor
runtime: node 24.18.0 (x64-linux)

benchmark                   avg (min … max) p75 / p99    (min … top 1%)
------------------------------------------- -------------------------------
gts small (control)             1.22 s/iter    1.27 s             █       █
                          (1.04 s … 1.47 s)    1.34 s ▅    ▅ ▅▅▅ ▅█   ▅   █
                    (148.62 mb … 156.84 mb) 151.44 mb █▁▁▁▁█▁███▁██▁▁▁█▁▁▁█

gts small (experiment)          1.18 s/iter    1.20 s     █       █        
                          (1.03 s … 1.36 s)    1.31 s ▅   █ ▅▅▅  ▅█     ▅ ▅
                    (138.73 mb … 192.98 mb) 152.35 mb █▁▁▁█▁███▁▁██▁▁▁▁▁█▁█

                             ┌                                            ┐
                              ╷               ┌──────────┬──────┐         ╷
         gts small (control)  ├───────────────┤          │      ├─────────┤
                              ╵               └──────────┴──────┘         ╵
                             ╷       ┌────────────┬───┐               ╷
      gts small (experiment) ├───────┤            │   ├───────────────┤
                             ╵       └────────────┴───┘               ╵
                             └                                            ┘
                             1.03 s              1.18 s              1.34 s

summary
  gts small (experiment)
   1.04x faster than gts small (control)

------------------------------------------- -------------------------------
gts medium (control)            2.19 s/iter    2.29 s           █          
                          (2.00 s … 2.51 s)    2.31 s           █         █
                    (331.76 mb … 351.37 mb) 338.41 mb █▁▁█▁▁███▁█▁▁▁▁▁▁▁█▁█

gts medium (experiment)         2.21 s/iter    2.25 s █    ██ ██ █ ██ ██  █
                          (2.04 s … 2.51 s)    2.31 s █    ██ ██ █ ██ ██  █
                    (325.51 mb … 337.49 mb) 329.55 mb █▁▁▁▁██▁██▁█▁██▁██▁▁█

                             ┌                                            ┐
                             ╷            ┌─────────────┬──────────────┐  ╷
        gts medium (control) ├────────────┤             │              ├──┤
                             ╵            └─────────────┴──────────────┘  ╵
                                  ╷           ┌────────────┬─────┐       ╷
     gts medium (experiment)      ├───────────┤            │     ├───────┤
                                  ╵           └────────────┴─────┘       ╵
                             └                                            ┘
                             2.00 s              2.16 s              2.31 s

summary
  gts medium (control)
   1.01x faster than gts medium (experiment)

------------------------------------------- -------------------------------
gts large (control)             1.05 s/iter    1.08 s    █                 
                       (957.11 ms … 1.35 s)    1.11 s ▅▅ █▅  ▅  ▅    ▅▅ ▅ ▅
                    (133.24 mb … 184.84 mb) 156.71 mb ██▁██▁▁█▁▁█▁▁▁▁██▁█▁█

gts large (experiment)          1.09 s/iter    1.12 s   █              █   
                       (992.49 ms … 1.35 s)    1.14 s ▅▅█  ▅  ▅   ▅  ▅ █  ▅
                    (123.17 mb … 180.05 mb) 148.46 mb ███▁▁█▁▁█▁▁▁█▁▁█▁█▁▁█

                             ┌                                            ┐
                             ╷    ┌─────────────────┬──────┐      ╷
         gts large (control) ├────┤                 │      ├──────┤
                             ╵    └─────────────────┴──────┘      ╵
                                      ╷  ┌──────────────────┬────────┐    ╷
      gts large (experiment)          ├──┤                  │        ├────┤
                                      ╵  └──────────────────┴────────┘    ╵
                             └                                            ┘
                             957.11 ms            1.05 s             1.14 s

summary
  gts large (control)
   1.03x faster than gts large (experiment)

------------------------------------------- -------------------------------
gjs small (control)             1.00 s/iter    1.03 s              █       
                       (875.08 ms … 1.23 s)    1.12 s     █        █       
                    (111.96 mb … 155.57 mb) 138.83 mb █▁▁▁████▁▁▁▁▁█▁▁█▁▁▁█

gjs small (experiment)          1.01 s/iter    1.06 s      █               
                       (887.16 ms … 1.22 s)    1.09 s ▅  ▅ █▅ ▅    ▅ ▅ ▅▅ ▅
                    (108.07 mb … 152.27 mb) 140.32 mb █▁▁█▁██▁█▁▁▁▁█▁█▁██▁█

                             ┌                                            ┐
                             ╷        ┌──────────────┬─────┐              ╷
         gjs small (control) ├────────┤              │     ├──────────────┤
                             ╵        └──────────────┴─────┘              ╵
                               ╷        ┌─────────────┬─────────┐     ╷
      gjs small (experiment)   ├────────┤             │         ├─────┤
                               ╵        └─────────────┴─────────┘     ╵
                             └                                            ┘
                             875.08 ms           995.20 ms           1.12 s

summary
  gjs small (control)
   1x faster than gjs small (experiment)

------------------------------------------- -------------------------------
gjs medium (control)            1.85 s/iter    1.91 s      ██             █
                          (1.73 s … 2.16 s)    1.95 s ▅ ▅  ██  ▅ ▅    ▅   █
                    (270.48 mb … 279.05 mb) 273.12 mb █▁█▁▁██▁▁█▁█▁▁▁▁█▁▁▁█

gjs medium (experiment)         1.88 s/iter    1.89 s █   █     █          
                          (1.76 s … 2.16 s)    2.00 s █  ▅█    ▅█▅▅       ▅
                    (256.25 mb … 309.90 mb) 281.11 mb █▁▁██▁▁▁▁████▁▁▁▁▁▁▁█

                             ┌                                            ┐
                             ╷        ┌───────────┬────────┐      ╷
        gjs medium (control) ├────────┤           │        ├──────┤
                             ╵        └───────────┴────────┘      ╵
                                   ╷     ┌────────────┬──┐                ╷
     gjs medium (experiment)       ├─────┤            │  ├────────────────┤
                                   ╵     └────────────┴──┘                ╵
                             └                                            ┘
                             1.73 s              1.86 s              2.00 s

summary
  gjs medium (control)
   1.01x faster than gjs medium (experiment)

------------------------------------------- -------------------------------
gjs large (control)          868.07 ms/iter 894.11 ms  █             █     
                       (784.23 ms … 1.11 s) 929.98 ms ▅█ ▅▅ ▅   ▅    █  ▅ ▅
                    (109.68 mb … 160.36 mb) 130.94 mb ██▁██▁█▁▁▁█▁▁▁▁█▁▁█▁█

gjs large (experiment)       876.83 ms/iter 911.79 ms    █                 
                       (792.55 ms … 1.11 s) 953.82 ms ▅▅▅█▅  ▅      ▅▅▅   ▅
                    ( 99.37 mb … 151.94 mb) 135.47 mb █████▁▁█▁▁▁▁▁▁███▁▁▁█

                             ┌                                            ┐
                             ╷ ┌───────────────────┬──────┐         ╷
         gjs large (control) ├─┤                   │      ├─────────┤
                             ╵ └───────────────────┴──────┘         ╵
                               ╷    ┌─────────────────┬────────┐          ╷
      gjs large (experiment)   ├────┤                 │        ├──────────┤
                               ╵    └─────────────────┴────────┘          ╵
                             └                                            ┘
                             784.23 ms         869.02 ms          953.82 ms

summary
  gjs large (control)
   1.01x faster than gjs large (experiment)

------------------------------------------- -------------------------------
hbs small (control)          176.01 ms/iter 182.74 ms    █                 
                    (148.97 ms … 276.90 ms) 191.35 ms ▅▅ █ ▅ ▅ ▅  ▅   ▅ ▅ ▅
                    ( 26.06 mb …  67.87 mb)  30.80 mb ██▁█▁█▁█▁█▁▁█▁▁▁█▁█▁█

hbs small (experiment)       176.22 ms/iter 183.15 ms            █         
                    (128.84 ms … 275.22 ms) 199.29 ms ▅     ▅ ▅▅▅█  ▅▅▅   ▅
                    ( 24.46 mb …  67.36 mb)  32.60 mb █▁▁▁▁▁█▁████▁▁███▁▁▁█

                             ┌                                            ┐
                                          ╷   ┌────────────┬───┐     ╷
         hbs small (control)              ├───┤            │   ├─────┤
                                          ╵   └────────────┴───┘     ╵
                             ╷                 ┌───────────┬────┐         ╷
      hbs small (experiment) ├─────────────────┤           │    ├─────────┤
                             ╵                 └───────────┴────┘         ╵
                             └                                            ┘
                             128.84 ms         164.07 ms          199.29 ms

summary
  hbs small (control)
   1x faster than hbs small (experiment)

------------------------------------------- -------------------------------
hbs medium (control)         960.95 ms/iter 981.89 ms █        ██          
                       (883.72 ms … 1.14 s)    1.08 s █▅▅ ▅▅   ██         ▅
                    (168.35 mb … 219.54 mb) 200.76 mb ███▁██▁▁▁██▁▁▁▁▁▁▁▁▁█

hbs medium (experiment)         1.01 s/iter    1.02 s █  █                 
                       (938.83 ms … 1.18 s)    1.09 s █  █▅ ▅ ▅▅ ▅  ▅     ▅
                    (144.91 mb … 199.41 mb) 185.47 mb █▁▁██▁█▁██▁█▁▁█▁▁▁▁▁█

                             ┌                                            ┐
                             ╷┌───────────────┬────┐                   ╷
        hbs medium (control) ├┤               │    ├───────────────────┤
                             ╵└───────────────┴────┘                   ╵
                                         ╷   ┌──────────┬──┐              ╷
     hbs medium (experiment)             ├───┤          │  ├──────────────┤
                                         ╵   └──────────┴──┘              ╵
                             └                                            ┘
                             883.72 ms           986.00 ms           1.09 s

summary
  hbs medium (control)
   1.05x faster than hbs medium (experiment)

------------------------------------------- -------------------------------
hbs large (control)          996.08 ms/iter    1.03 s   █                  
                       (928.96 ms … 1.17 s)    1.06 s   ██                 
                    (152.35 mb … 156.63 mb) 153.82 mb █▁██▁▁▁▁▁▁█▁█▁▁▁██▁▁█

hbs large (experiment)          1.03 s/iter    1.06 s ██ █  ██ █   █ █ ██ █
                       (938.54 ms … 1.20 s)    1.09 s ██ █  ██ █   █ █ ██ █
                    (129.49 mb … 188.84 mb) 158.32 mb ██▁█▁▁██▁█▁▁▁█▁█▁██▁█

                             ┌                                            ┐
                             ╷   ┌──────────────┬─────────┐      ╷
         hbs large (control) ├───┤              │         ├──────┤
                             ╵   └──────────────┴─────────┘      ╵
                                ╷      ┌─────────────────┬─────────┐      ╷
      hbs large (experiment)    ├──────┤                 │         ├──────┤
                                ╵      └─────────────────┴─────────┘      ╵
                             └                                            ┘
                             928.96 ms            1.01 s             1.09 s

summary
  hbs large (control)
   1.03x faster than hbs large (experiment)

NullVoxPopuli · 2026-07-02T01:58:56Z

@copilot good, now find out where the fix should be, or if we need to improve the error coming from content_tag -- or if we need to open a failing test PR on content_tag

Copilot · 2026-07-02T02:02:44Z

@copilot good, now find out where the fix should be, or if we need to improve the error coming from content_tag -- or if we need to open a failing test PR on content_tag

Found this in our transformForLint, not content-tag: content-tag returns the expected template range/content, but our placeholder escaped backticks inside comments, increasing the replacement length and tripping bad transform. Fixed in 1e7c572 by masking template contents for the lint placeholder while preserving output length/line breaks.

NullVoxPopuli · 2026-07-02T02:35:15Z

  let jsCode = code;
  for (const tplInfo of [...result].reverse()) {
-    const content = tplInfo.contents.replace(/`/g, '\\`').replace(/\$/g, '\\$');
+    const content = tplInfo.contents.replace(/[^\r\n]/g, ' ');


@copilot why is this the fix? what are we replacing (windows line endings)(?) with?

The fix is in the lint-only placeholder path: we don't need template contents there, only stable offsets/lines for TS/ESLint. The replacement now masks every non-line-ending character in the template body with a space, while preserving \r and \n (including CRLF) unchanged. That prevents comment backticks/${...} from changing the JS template literal placeholder length or syntax. Clarified this in f864056.

Initial plan

ead065b

Copilot AI assigned Copilot and NullVoxPopuli Jul 2, 2026

Copilot started work on behalf of NullVoxPopuli July 2, 2026 00:41 View session

Copilot AI linked an issue Jul 2, 2026 that may be closed by this pull request

Parser breaks on a specific template #226

Closed

Add failing transform regression test

e92bf8f

Copilot AI changed the title ~~[WIP] Add failing test for parser breaking on specific template~~ Add regression test for GTS transform with backtick comments Jul 2, 2026

Copilot AI requested a review from NullVoxPopuli July 2, 2026 00:43

Copilot finished work on behalf of NullVoxPopuli July 2, 2026 00:43

Copilot started work on behalf of NullVoxPopuli July 2, 2026 01:59 View session

Fix lint transform for backtick template comments

1e7c572

Copilot finished work on behalf of NullVoxPopuli July 2, 2026 02:03

NullVoxPopuli reviewed Jul 2, 2026

View reviewed changes

Copilot started work on behalf of NullVoxPopuli July 2, 2026 02:35 View session

Clarify lint template masking

f864056

Copilot finished work on behalf of NullVoxPopuli July 2, 2026 02:38

Copilot AI requested a review from NullVoxPopuli July 2, 2026 02:38

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Merge branch 'main' into copilot/add-failing-test-for-parser

b21478a

NullVoxPopuli marked this pull request as ready for review July 2, 2026 03:23

NullVoxPopuli approved these changes Jul 2, 2026

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NullVoxPopuli merged commit 8dc030b into main Jul 2, 2026
74 of 75 checks passed

NullVoxPopuli deleted the copilot/add-failing-test-for-parser branch July 2, 2026 20:50

github-actions Bot mentioned this pull request Jul 2, 2026

Prepare Release v0.14.1 #224

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NullVoxPopuli added the bug Something isn't working label Jul 2, 2026

NullVoxPopuli changed the title ~~Add regression test for GTS transform with backtick comments~~ Fix issue with GTS transform with backtick comments Jul 2, 2026

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Fix issue with GTS transform with backtick comments#227

Fix issue with GTS transform with backtick comments#227
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🏎️ Benchmark Comparison

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