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(c_expand_return): Issue a warning if returning address of non-static 

local object.

From-SVN: r6405
This commit is contained in:
Richard Kenner 1994-01-22 17:18:10 -05:00
parent 3a19aabc45
commit 88a3dbc1a9
1 changed files with 27 additions and 3 deletions
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30
gcc/c-typeck.c
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@ -1,5 +1,5 @@
/* Build expressions with type checking for C compiler.
Copyright (C) 1987, 1988, 1989, 1992, 1993 Free Software Foundation, Inc.
Copyright (C) 1987, 88, 91, 92, 93, 1994 Free Software Foundation, Inc.
This file is part of GNU CC.
@ -6202,12 +6202,36 @@ c_expand_return (retval)
tree t = convert_for_assignment (valtype, retval, "return",
NULL_TREE, NULL_TREE, 0);
tree res = DECL_RESULT (current_function_decl);
tree inner;
if (t == error_mark_node)
return;
t = build (MODIFY_EXPR, TREE_TYPE (res),
res, convert (TREE_TYPE (res), t));
inner = t = convert (TREE_TYPE (res), t);
/* Strip any conversions, additions, and subtractions, and see if
we are returning the address of a local variable. Warn if so. */
while (TREE_CODE (inner) == NOP_EXPR
|| TREE_CODE (inner) == NON_LVALUE_EXPR
|| TREE_CODE (inner) == CONVERT_EXPR
|| TREE_CODE (inner) == PLUS_EXPR
|| TREE_CODE (inner) == MINUS_EXPR)
inner = TREE_OPERAND (inner, 0);
if (TREE_CODE (inner) == ADDR_EXPR)
{
inner = TREE_OPERAND (inner, 0);
while (TREE_CODE_CLASS (TREE_CODE (inner)) == 'r')
inner = TREE_OPERAND (inner, 0);
if (TREE_CODE (inner) == VAR_DECL
&& ! TREE_STATIC (inner)
&& DECL_CONTEXT (inner) == current_function_decl)
warning ("function returns address of local variable");
}
t = build (MODIFY_EXPR, TREE_TYPE (res), res, t);
TREE_SIDE_EFFECTS (t) = 1;
expand_return (t);
current_function_returns_value = 1;