Test the consistency of shells with regard to parsing empty bodies.

Brought up by Yorwba.

OSH seems to be the most consistent.

spec/empty-bodies.test.sh

@@ -0,0 +1,25 @@
#!/usr/bin/env bash

### Empty do/done
while false; do
done
echo empty
# stdout: empty
# OK dash/bash stdout-json: ""
# OK dash/bash status: 2

### Empty case/esac
case foo in
esac
echo empty
# stdout: empty

### empty then/fi
if foo; then
fi
echo empty
# stdout: empty
# OK dash/bash stdout-json: ""
# OK dash/bash status: 2
# OK mksh stdout-json: ""
# OK mksh status: 1

spec/for-expr.test.sh

@@ -41,3 +41,4 @@ done  # A construct borrowed from ksh93.
3
## N-I mksh status: 1
## N-I mksh stdout-json: ""

test/spec.sh

@@ -550,6 +550,10 @@ for-expr() {
    $MKSH $BASH $OSH "$@"
}

empty-bodies() {
  sh-spec spec/empty-bodies.test.sh "${REF_SHELLS[@]}" $OSH
}

# TODO: This is for the ANTLR grammars, in the oil-sketch repo.
# osh has infinite loop?
shell-grammar() {