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// Copyright (C) 2021-2025 Free Software Foundation, Inc.
// This file is part of GCC.
// GCC is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3, or (at your option) any later
// version.
// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
// for more details.
// You should have received a copy of the GNU General Public License
// along with GCC; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
#include "rust-readonly-check.h"
#include "rust-tree.h"
#include "rust-gcc.h"
#include "print-tree.h"
namespace Rust {
namespace Analysis {
static std::map<tree, int> assignment_map = {};
// ported over from c-family/c-warn.cc
void
readonly_error (location_t loc, tree arg, enum lvalue_use use)
{
gcc_assert (use == lv_assign || use == lv_increment || use == lv_decrement
|| use == lv_asm);
STRIP_ANY_LOCATION_WRAPPER (arg);
/* Using this macro rather than (for example) arrays of messages
ensures that all the format strings are checked at compile
time. */
#define READONLY_MSG(A, I, D, AS) \
(use == lv_assign \
? (A) \
: (use == lv_increment ? (I) : (use == lv_decrement ? (D) : (AS))))
if (TREE_CODE (arg) == COMPONENT_REF)
{
if (TYPE_READONLY (TREE_TYPE (TREE_OPERAND (arg, 0))))
error_at (loc,
READONLY_MSG (G_ ("assignment of member "
"%qD in read-only object"),
G_ ("increment of member "
"%qD in read-only object"),
G_ ("decrement of member "
"%qD in read-only object"),
G_ ("member %qD in read-only object "
"used as %<asm%> output")),
TREE_OPERAND (arg, 1));
else
error_at (
loc,
READONLY_MSG (G_ ("assignment of read-only member %qD"),
G_ ("increment of read-only member %qD"),
G_ ("decrement of read-only member %qD"),
G_ ("read-only member %qD used as %<asm%> output")),
TREE_OPERAND (arg, 1));
}
else if (VAR_P (arg))
error_at (loc,
READONLY_MSG (G_ ("assignment of read-only variable %qD"),
G_ ("increment of read-only variable %qD"),
G_ ("decrement of read-only variable %qD"),
G_ (
"read-only variable %qD used as %<asm%> output")),
arg);
else if (TREE_CODE (arg) == PARM_DECL)
error_at (loc,
READONLY_MSG (G_ ("assignment of read-only parameter %qD"),
G_ ("increment of read-only parameter %qD"),
G_ ("decrement of read-only parameter %qD"),
G_ (
"read-only parameter %qD use as %<asm%> output")),
arg);
else if (TREE_CODE (arg) == RESULT_DECL)
{
error_at (loc,
READONLY_MSG (G_ ("assignment of "
"read-only named return value %qD"),
G_ ("increment of "
"read-only named return value %qD"),
G_ ("decrement of "
"read-only named return value %qD"),
G_ ("read-only named return value %qD "
"used as %<asm%>output")),
arg);
}
else if (TREE_CODE (arg) == FUNCTION_DECL)
error_at (loc,
READONLY_MSG (G_ ("assignment of function %qD"),
G_ ("increment of function %qD"),
G_ ("decrement of function %qD"),
G_ ("function %qD used as %<asm%> output")),
arg);
else
error_at (loc,
READONLY_MSG (G_ ("assignment of read-only location %qE"),
G_ ("increment of read-only location %qE"),
G_ ("decrement of read-only location %qE"),
G_ (
"read-only location %qE used as %<asm%> output")),
arg);
}
static void
emit_error (tree *t, tree lhs, enum lvalue_use use)
{
readonly_error (EXPR_LOCATION (*t), lhs, use);
TREE_OPERAND (*t, 0) = error_mark_node;
}
static void
check_modify_expr (tree *t)
{
tree lhs = TREE_OPERAND (*t, 0);
if (TREE_CODE (lhs) == ARRAY_REF || TREE_CODE (lhs) == COMPONENT_REF)
lhs = TREE_OPERAND (lhs, 0);
tree lhs_type = TREE_TYPE (lhs);
if (TYPE_READONLY (lhs_type) || TREE_READONLY (lhs) || TREE_CONSTANT (lhs))
{
if (TREE_CODE (lhs) != VAR_DECL)
emit_error (t, lhs, lv_assign);
else if (!DECL_ARTIFICIAL (lhs))
{
if (DECL_INITIAL (lhs) != NULL)
emit_error (t, lhs, lv_assign);
else
{
if (assignment_map.find (lhs) == assignment_map.end ())
{
assignment_map.insert ({lhs, 0});
}
assignment_map[lhs]++;
if (assignment_map[lhs] > 1)
emit_error (t, lhs, lv_assign);
}
}
}
}
static void
check_decl (tree *t)
{
switch (TREE_CODE (*t))
{
case MODIFY_EXPR:
check_modify_expr (t);
break;
default:
break;
}
}
static tree
readonly_walk_fn (tree *t, int *, void *)
{
check_decl (t);
return NULL_TREE;
}
void
ReadonlyCheck::Lint (Compile::Context &ctx)
{
assignment_map.clear ();
for (auto &fndecl : ctx.get_func_decls ())
{
for (tree p = DECL_ARGUMENTS (fndecl); p != NULL_TREE; p = DECL_CHAIN (p))
{
check_decl (&p);
}
walk_tree_without_duplicates (&DECL_SAVED_TREE (fndecl),
&readonly_walk_fn, &ctx);
}
assignment_map.clear ();
for (auto &var : ctx.get_var_decls ())
{
tree decl = var->get_decl ();
check_decl (&decl);
}
assignment_map.clear ();
for (auto &const_decl : ctx.get_const_decls ())
{
check_decl (&const_decl);
}
}
} // namespace Analysis
} // namespace Rust
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