Shell script syntax highlighting fails with indented EOT HereDoc

[sandy-fairsupply]

Type: Bug

POSIX shell scripts that use an indented EOT marker break syntax highlighting for the remainder of the file. In the following shell script:

• The last two lines ) and echo "$foo" appear to be part of the HereDoc, but they should not be
• The opening paren ( is marked as an error (unmatched), but it should not be.

#!/bin/sh
foo=$(cat <<'    EOT'
        A HereDoc
    EOT
)
echo "$foo"

Screenshot showing the incorrect highlighting:

In both Bash and Dash, the script runs without error and outputs A HereDoc\n as expected.

Related issue: #77675. That issue was closed by PR #169118, which adopted a different grammar. Technically this issue is a duplicate, but the original problem was not fixed; indeed @jeff-hykin said "#77675 (code example at top of this issue) is not [fixed]".

Note that in POSIX, Bash's indented HereDoc syntax <<-'EOT' in not available.

VS Code version: Code 1.91.1 (Universal) (f1e16e1, 2024-07-09T22:07:54.982Z)
OS version: Darwin arm64 23.5.0
Modes:

System Info

Item	Value
CPUs	Apple M2 (8 x 2400)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: enabled_on direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled webgl: enabled webgl2: enabled webgpu: enabled
Load (avg)	5, 3, 4
Memory (System)	24.00GB (1.84GB free)
Process Argv	--disable-extensions --crash-reporter-id 71395059-61c9-412b-873d-3c471fa4f758
Screen Reader	no
VM	0%

Extensions disabled

A/B Experiments

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pythonnoceb:30805159
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pythonregdiag2:30936856
pythonmypyd1:30879173
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pythontbext0:30879054
accentitlementsc:30995553
dsvsc016:30899300
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dsvsc018:30899302
cppperfnew:31000557
dsvsc020:30976470
pythonait:31006305
dsvsc021:30996838
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pythoncenvpt:31062603
a69g1124:31058053
dvdeprecation:31068756
dwnewjupyter:31046869
impr_priority:31094925
refactorc:31101458
ccplti:31098112

[alexr00]

Thanks for all the details! Moved to jeff-hykin/better-shell-syntax#97.