[osh/cmd_parse] Fix crash parsing return = x

This is issue #2003.

Also reproduce osh-cpp bugs from Koiche.

Author: Andy C

osh/cmd_parse.py

@@ -2427,9 +2427,9 @@ def ParseCommand(self):
                 part0 = parts[0]
                 if part0.tag() == word_part_e.Literal:
                     tok = cast(Token, part0)
-                    if (match.IsValidVarName(lexer.LazyStr(tok)) and
-                            self.w_parser.LookPastSpace() == Id.Lit_Equals):
-                        assert tok.id == Id.Lit_Chars, tok
+                    if (tok.id == Id.Lit_Chars and
+                            self.w_parser.LookPastSpace() == Id.Lit_Equals and
+                            match.IsValidVarName(lexer.LazyStr(tok))):
 
                         if (len(self.hay_attrs_stack) and
                                 self.hay_attrs_stack[-1]):

spec/bugs.test.sh

@@ -1,4 +1,3 @@
-
 ## compare_shells: bash dash mksh zsh ash
 ## oils_failures_allowed: 0
 
@@ -360,3 +359,26 @@ PWNED
 0
 ## END
 
+#### printf bugs (Koiche on Zulip)
+printf '%x\n' 2147483648
+printf '%u\n' 2147483648
+## STDOUT:
+80000000
+2147483648
+## END
+
+#### bit shift bug (Koiche on Zulip)
+case $SH in dash|ash) exit ;; esac
+
+(( 1 << 32 ))
+echo status=$?
+
+(( 1 << 32 )) && echo yes
+
+## STDOUT:
+status=0
+yes
+## END
+
+## N-I dash/ash STDOUT:
+## END

spec/ysh-bugs.test.sh

@@ -149,3 +149,18 @@ echo $Q
 world
 ## END
 
+
+#### Parsing crash - bug #2003
+
+set +o errexit
+
+$SH -c 'proc y (;x) { return = x }'
+echo status=$?
+
+$SH -c 'func y (;x) { return = x }'
+echo status=$?
+
+## STDOUT:
+status=2
+status=2
+## END