Try harder to diagnose problem instead of reporting undeclared type

[usev6]

Fixes RT #125902

[AlexDaniel]

Can we have this rebased to resolve the conflict? Ping @usev6

[usev6]

I'll test my changes with current nom and push an updated version.

[AlexDaniel]

I see no problem with this PR. It may be over-engineered as you say, but it gives awesome error messages. I was able to reproduce all of them:

my Str where ‘foo’ $test;

===SORRY!=== Error while compiling -e
Malformed my (found type followed by constraint; did you forget a variable in between?)
at -e:1
------> my Str ⏏where ‘foo’ $test;

my Int is default(42)

===SORRY!=== Error while compiling -e
Malformed my (found type followed by trait; did you forget a variable in between?)
at -e:1
------> my Int ⏏is default(42)

my Str;

===SORRY!=== Error while compiling -e
Malformed my (did you forget a variable after type?)
at -e:1
------> my Str⏏;

Without this PR it simply says “malformed my” which is arguably LTA. Spectest clean, merging.

[jonathanstowe]

👍