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bpo-32836: Remove temporary variable usage #5680

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Merged
ncoghlan merged 3 commits into from
Feb 26, 2018
Merged

bpo-32836: Remove temporary variable usage #5680

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db06c61
Removed temp variable usage
nitishch Feb 14, 2018
d3c2862
Merge branch 'master' of https://github.com/python/cpython into bpo-3…
nitishch Feb 14, 2018
f4a116b
Added NEWS entry
nitishch Feb 14, 2018
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1 change: 0 additions & 1 deletion Include/symtable.h
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Original file line number Diff line number Diff line change
Expand Up @@ -60,7 +60,6 @@ typedef struct _symtable_entry {
int ste_col_offset; /* offset of first line of block */
int ste_opt_lineno; /* lineno of last exec or import * */
int ste_opt_col_offset; /* offset of last exec or import * */
int ste_tmpname; /* counter for listcomp temp vars */
struct symtable *ste_table;
} PySTEntryObject;

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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core and Builtins/2018-02-14-12-35-47.bpo-32836.bThJnx.rst
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@@ -0,0 +1 @@
Don't use temporary variables in cases of list/dict/set comprehensions
25 changes: 0 additions & 25 deletions Python/symtable.c
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Expand Up @@ -69,7 +69,6 @@ ste_new(struct symtable *st, identifier name, _Py_block_ty block,
ste->ste_varkeywords = 0;
ste->ste_opt_lineno = 0;
ste->ste_opt_col_offset = 0;
ste->ste_tmpname = 0;
ste->ste_lineno = lineno;
ste->ste_col_offset = col_offset;

Expand Down Expand Up @@ -1082,24 +1081,6 @@ symtable_add_def(struct symtable *st, PyObject *name, int flag)
} \
}

static int
symtable_new_tmpname(struct symtable *st)
{
char tmpname[256];
identifier tmp;

PyOS_snprintf(tmpname, sizeof(tmpname), "_[%d]",
++st->st_cur->ste_tmpname);
tmp = PyUnicode_InternFromString(tmpname);
if (!tmp)
return 0;
if (!symtable_add_def(st, tmp, DEF_LOCAL))
return 0;
Py_DECREF(tmp);
return 1;
}


static int
symtable_record_directive(struct symtable *st, identifier name, stmt_ty s)
{
Expand Down Expand Up @@ -1723,7 +1704,6 @@ symtable_handle_comprehension(struct symtable *st, expr_ty e,
expr_ty elt, expr_ty value)
{
int is_generator = (e->kind == GeneratorExp_kind);
int needs_tmp = !is_generator;
comprehension_ty outermost = ((comprehension_ty)
asdl_seq_GET(generators, 0));
/* Outermost iterator is evaluated in current scope */
Expand All @@ -1742,11 +1722,6 @@ symtable_handle_comprehension(struct symtable *st, expr_ty e,
symtable_exit_block(st, (void *)e);
return 0;
}
/* Allocate temporary name if needed */
if (needs_tmp && !symtable_new_tmpname(st)) {
symtable_exit_block(st, (void *)e);
return 0;
}
VISIT(st, expr, outermost->target);
VISIT_SEQ(st, expr, outermost->ifs);
VISIT_SEQ_TAIL(st, comprehension, generators, 1);
Expand Down