fix an ambiguity in the grammar from the implementation of extended unpacking

(one which was strangely "resolved" by pgen)

This also kills the unused testlist1 rule and fixes parse tree validation of
extended unpacking.

1 files changed, 7 insertions, 8 deletions

diff --git a/Grammar/Grammar b/Grammar/Grammar
index 1f226b80b1..19f67dee5e 100644
--- a/Grammar/Grammar
+++ b/Grammar/Grammar
@@ -37,8 +37,9 @@ stmt: simple_stmt | compound_stmt
 simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
 small_stmt: (expr_stmt | del_stmt | pass_stmt | flow_stmt |
              import_stmt | global_stmt | nonlocal_stmt | assert_stmt)
-expr_stmt: testlist (augassign (yield_expr|testlist) |
-                     ('=' (yield_expr|testlist))*)
+expr_stmt: testlist_star_expr (augassign (yield_expr|testlist) |
+                     ('=' (yield_expr|testlist_star_expr))*)
+testlist_star_expr: (test|star_expr) (',' (test|star_expr))* [',']
 augassign: ('+=' | '-=' | '*=' | '/=' | '%=' | '&=' | '|=' | '^=' |
             '<<=' | '>>=' | '**=' | '//=')
 # For normal assignments, additional restrictions enforced by the interpreter
@@ -86,9 +87,9 @@ lambdef_nocond: 'lambda' [varargslist] ':' test_nocond
 or_test: and_test ('or' and_test)*
 and_test: not_test ('and' not_test)*
 not_test: 'not' not_test | comparison
-comparison: star_expr (comp_op star_expr)*
+comparison: expr (comp_op expr)*
 comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'
-star_expr: ['*'] expr
+star_expr: '*' expr
 expr: xor_expr ('|' xor_expr)*
 xor_expr: and_expr ('^' and_expr)*
 and_expr: shift_expr ('&' shift_expr)*
@@ -101,12 +102,12 @@ atom: ('(' [yield_expr|testlist_comp] ')' |
        '[' [testlist_comp] ']' |
        '{' [dictorsetmaker] '}' |
        NAME | NUMBER | STRING+ | '...' | 'None' | 'True' | 'False')
-testlist_comp: test ( comp_for | (',' test)* [','] )
+testlist_comp: (test|star_expr) ( comp_for | (',' (test|star_expr))* [','] )
 trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
 subscriptlist: subscript (',' subscript)* [',']
 subscript: test | [test] ':' [test] [sliceop]
 sliceop: ':' [test]
-exprlist: star_expr (',' star_expr)* [',']
+exprlist: (expr|star_expr) (',' (expr|star_expr))* [',']
 testlist: test (',' test)* [',']
 dictorsetmaker: ( (test ':' test (comp_for | (',' test ':' test)* [','])) |
                   (test (comp_for | (',' test)* [','])) )
@@ -123,8 +124,6 @@ comp_iter: comp_for | comp_if
 comp_for: 'for' exprlist 'in' or_test [comp_iter]
 comp_if: 'if' test_nocond [comp_iter]
 
-testlist1: test (',' test)*
-
 # not used in grammar, but may appear in "node" passed from Parser to Compiler
 encoding_decl: NAME