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the Slice in x[::] has to have step as None to help the interpreter
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3 changed files with 17 additions and 5 deletions
16
Python/ast.c
16
Python/ast.c
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@ -1471,7 +1471,21 @@ ast_for_slice(struct compiling *c, const node *n)
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ch = CHILD(n, NCH(n) - 1);
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if (TYPE(ch) == sliceop) {
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if (NCH(ch) != 1) {
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if (NCH(ch) == 1) {
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/*
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This is an extended slice (ie "x[::]") with no expression in the
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step field. We set this literally to "None" in order to
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disambiguate it from x[:]. (The interpreter might have to call
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__getslice__ for x[:], but it must call __getitem__ for x[::].)
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*/
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identifier none = new_identifier("None", c->c_arena);
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if (!none)
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return NULL;
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ch = CHILD(ch, 0);
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step = Name(none, Load, LINENO(ch), ch->n_col_offset, c->c_arena);
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if (!step)
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return NULL;
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} else {
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ch = CHILD(ch, 1);
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if (TYPE(ch) == test) {
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step = ast_for_expr(c, ch);
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