When scanning JSON, upon encountering an invalid token, we immediately
return. Previously this return happened without inserting an EOF token.
Since other functions assume that a token sequence always ends in EOF,
this could cause a panic.
This commit adds a synthetic EOF token after the invalid token before
returning. While this does not match the real end-of-file of the source
JSON, it is marking the end of the scanned bytes, so it seems reasonable.
Fixes#339
HCL uses grapheme cluster segmentation to produce accurate "column"
indications in diagnostic messages and other human-oriented source
location information. Each new major version of Unicode introduces new
codepoints, some of which are defined to combine with other codepoints to
produce a single visible character (grapheme cluster).
We were previously using the rules from Unicode 9.0.0. This change
switches to using the segmentation rules from Unicode 12.0.0, which is
the latest version at the time of this commit and is also the version of
Unicode used for other purposes by the Go 1.14 runtime.
HCL does not use text segmentation results for any purpose that would
affect the meaning of decoded data extracted from HCL files, so this
change will only affect the human-oriented source positions generated for
files containing characters that were newly-introduced in Unicode 10, 11,
or 12. (Machine-oriented uses of source location information are based on
byte offsets and not affected by text segmentation.)
