Very subtle syntax change: in a list comprehension, the testlist in · sthagen/python-cpython@1c91707 · GitHub
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Very subtle syntax change: in a list comprehension, the testlist in
"for <var> in <testlist> may no longer be a single test followed by a comma. This solves SF bug #431886. Note that if the testlist contains more than one test, a trailing comma is still allowed, for maximum backward compatibility; but this example is not: [(x, y) for x in range(10), for y in range(10)] ^ The fix involved creating a new nonterminal 'testlist_safe' whose definition doesn't allow the trailing comma if there's only one test: testlist_safe: test [(',' test)+ [',']]
1 parent 69c0ff3 commit 1c91707

5 files changed

Lines changed: 150 additions & 111 deletions

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‎Grammar/Grammar‎

Lines changed: 2 additions & 1 deletion

‎Include/graminit.h‎

Lines changed: 8 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -56,10 +56,11 @@
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#define sliceop 311
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#define exprlist 312
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#define testlist 313
59-
#define dictmaker 314
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#define classdef 315
61-
#define arglist 316
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#define argument 317
63-
#define list_iter 318
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#define list_for 319
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#define list_if 320
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#define testlist_safe 314
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#define dictmaker 315
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#define classdef 316
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#define arglist 317
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#define argument 318
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#define list_iter 319
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#define list_for 320
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#define list_if 321

‎Modules/parsermodule.c‎

Lines changed: 9 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1039,6 +1039,14 @@ validate_testlist(node *tree)
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}
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static int
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validate_testlist_safe(node *tree)
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{
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return (validate_repeating_list(tree, testlist_safe,
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validate_test, "testlist_safe"));
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}
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/* '*' NAME [',' '**' NAME] | '**' NAME
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*/
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static int
@@ -1218,7 +1226,7 @@ validate_list_for(node *tree)
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res = (validate_name(CHILD(tree, 0), "for")
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&& validate_exprlist(CHILD(tree, 1))
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&& validate_name(CHILD(tree, 2), "in")
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&& validate_testlist(CHILD(tree, 3)));
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&& validate_testlist_safe(CHILD(tree, 3)));
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return res;
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}

‎Python/compile.c‎

Lines changed: 1 addition & 0 deletions

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