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macros: Do not try and re-expand if depth has exceeded recursion limit 

We need to limit the amount of times that macro get expanded recursively
during macro-expansion. This limits the amount of times an ASTFragment
can be visited by simply incrementing the depth when setting a fragment,
and decreasing it when taking one. This way, recursive expansion which
happens at the expansion level (instead of the matching level) will
still get caught
This commit is contained in:
Arthur Cohen 2022-03-14 10:36:09 +01:00
parent 41f402f0b1
commit 02887c88f5
4 changed files with 33 additions and 38 deletions
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49
gcc/rust/expand/rust-attribute-visitor.cc
View File

@ -315,7 +315,6 @@ AttrVisitor::visit (AST::MacroInvocation &macro_invoc)
// I don't think any macro token trees can be stripped in any way
// TODO: maybe have cfg! macro stripping behaviour here?
if (macro_invoc.has_semicolon ())
expander.expand_invoc_semi (macro_invoc);
else
@ -532,23 +531,17 @@ AttrVisitor::visit (AST::ArithmeticOrLogicalExpr &expr)
* with outer expr */
auto &l_expr = expr.get_left_expr ();
l_expr->accept_vis (*this);
auto l_fragment = expander.take_expanded_fragment ();
auto l_fragment = expander.take_expanded_fragment (*this);
if (l_fragment.should_expand ())
{
l_fragment.accept_vis (*this);
l_expr = l_fragment.take_expression_fragment ();
}
l_expr = l_fragment.take_expression_fragment ();
/* should syntactically not have outer attributes, though this may
* not have worked in practice */
auto &r_expr = expr.get_right_expr ();
r_expr->accept_vis (*this);
auto r_fragment = expander.take_expanded_fragment ();
auto r_fragment = expander.take_expanded_fragment (*this);
if (r_fragment.should_expand ())
{
r_fragment.accept_vis (*this);
r_expr = r_fragment.take_expression_fragment ();
}
r_expr = r_fragment.take_expression_fragment ();
// ensure that they are not marked for strip
if (expr.get_left_expr ()->is_marked_for_strip ())
@ -666,23 +659,17 @@ AttrVisitor::visit (AST::CompoundAssignmentExpr &expr)
* with outer expr */
auto &l_expr = expr.get_left_expr ();
l_expr->accept_vis (*this);
auto l_frag = expander.take_expanded_fragment ();
auto l_frag = expander.take_expanded_fragment (*this);
if (l_frag.should_expand ())
{
l_frag.accept_vis (*this);
l_expr = l_frag.take_expression_fragment ();
}
l_expr = l_frag.take_expression_fragment ();
/* should syntactically not have outer attributes, though this may
* not have worked in practice */
auto &r_expr = expr.get_right_expr ();
r_expr->accept_vis (*this);
auto r_frag = expander.take_expanded_fragment ();
auto r_frag = expander.take_expanded_fragment (*this);
if (r_frag.should_expand ())
{
r_frag.accept_vis (*this);
r_expr = r_frag.take_expression_fragment ();
}
r_expr = r_frag.take_expression_fragment ();
// ensure that they are not marked for strip
if (expr.get_left_expr ()->is_marked_for_strip ())
@ -1033,10 +1020,9 @@ AttrVisitor::visit (AST::CallExpr &expr)
stmt->accept_vis (*this);
auto fragment = expander.take_expanded_fragment ();
auto fragment = expander.take_expanded_fragment (*this);
if (fragment.should_expand ())
{
fragment.accept_vis (*this);
// Remove the current expanded invocation
it = params.erase (it);
for (auto &node : fragment.get_nodes ())
@ -1157,10 +1143,9 @@ AttrVisitor::visit (AST::BlockExpr &expr)
stmt->accept_vis (*this);
auto fragment = expander.take_expanded_fragment ();
auto fragment = expander.take_expanded_fragment (*this);
if (fragment.should_expand ())
{
fragment.accept_vis (*this);
// Remove the current expanded invocation
it = stmts.erase (it);
for (auto &node : fragment.get_nodes ())
@ -1182,12 +1167,9 @@ AttrVisitor::visit (AST::BlockExpr &expr)
auto &tail_expr = expr.get_tail_expr ();
tail_expr->accept_vis (*this);
auto fragment = expander.take_expanded_fragment ();
auto fragment = expander.take_expanded_fragment (*this);
if (fragment.should_expand ())
{
fragment.accept_vis (*this);
tail_expr = fragment.take_expression_fragment ();
}
tail_expr = fragment.take_expression_fragment ();
if (tail_expr->is_marked_for_strip ())
expr.strip_tail_expr ();
@ -3031,12 +3013,9 @@ AttrVisitor::visit (AST::LetStmt &stmt)
"cannot strip expression in this position - outer "
"attributes not allowed");
auto fragment = expander.take_expanded_fragment ();
auto fragment = expander.take_expanded_fragment (*this);
if (fragment.should_expand ())
{
fragment.accept_vis (*this);
init_expr = fragment.take_expression_fragment ();
}
init_expr = fragment.take_expression_fragment ();
}
}
void

3
gcc/rust/expand/rust-macro-expand.cc
View File

@ -379,10 +379,9 @@ MacroExpander::expand_crate ()
// mark for stripping if required
item->accept_vis (attr_visitor);
auto fragment = take_expanded_fragment ();
auto fragment = take_expanded_fragment (attr_visitor);
if (fragment.should_expand ())
{
fragment.accept_vis (attr_visitor);
// Remove the current expanded invocation
it = items.erase (it);
for (auto &node : fragment.get_nodes ())

9
gcc/rust/expand/rust-macro-expand.h
View File

@ -287,11 +287,18 @@ struct MacroExpander
expanded_fragment = std::move (fragment);
}
AST::ASTFragment take_expanded_fragment ()
AST::ASTFragment take_expanded_fragment (AST::ASTVisitor &vis)
{
AST::ASTFragment old_fragment = std::move (expanded_fragment);
expanded_fragment = AST::ASTFragment::create_empty ();
for (auto &node : old_fragment.get_nodes ())
{
expansion_depth++;
node.accept_vis (vis);
expansion_depth--;
}
return old_fragment;
}

10
gcc/testsuite/rust/compile/macro17.rs Normal file
View File

@ -0,0 +1,10 @@
macro_rules! rep {
($a:literal) => { $a }; // { dg-error "reached recursion limit" }
($a:literal $(, $e:literal)*) => { // { dg-error "reached recursion limit" }
$a + rep!(0 $(, $e)*) // { dg-error "Failed to match" }
}
}
fn main() -> i32 {
rep!(1, 2)
}