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* [gcc/devel/rust/master] macro: Add assertion to avoid undefined behavior
@ 2022-06-08 12:45 Thomas Schwinge
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From: Thomas Schwinge @ 2022-06-08 12:45 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:2959ff8e7dd8b06bee76636af84c5aee06971397
commit 2959ff8e7dd8b06bee76636af84c5aee06971397
Author: Arthur Cohen <arthur.cohen@embecosm.com>
Date: Tue May 10 15:10:59 2022 +0200
macro: Add assertion to avoid undefined behavior
This also fixes the undefined behavior. Once again we are hurt by
`std::vector<T>::back()` returning references and not
pointers/`std::optional<T>`s!
The cause of the bug was some overzealous popping from the context
vector in block expressions. The amount of calls to `pop_context` is now
the same as the amount of calls to `push_context`
Diff:
---
gcc/rust/expand/rust-attribute-visitor.cc | 2 --
gcc/rust/expand/rust-macro-expand.h | 3 +++
gcc/testsuite/rust/compile/macro-issue1233.rs | 22 ++++++++++++++++++++++
3 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/gcc/rust/expand/rust-attribute-visitor.cc b/gcc/rust/expand/rust-attribute-visitor.cc
index 771f034a5bb..c7c6867dd10 100644
--- a/gcc/rust/expand/rust-attribute-visitor.cc
+++ b/gcc/rust/expand/rust-attribute-visitor.cc
@@ -1193,7 +1193,6 @@ AttrVisitor::visit (AST::BlockExpr &expr)
if (expander.fails_cfg_with_expand (expr.get_outer_attrs ()))
{
expr.mark_for_strip ();
- expander.pop_context ();
return;
}
@@ -1203,7 +1202,6 @@ AttrVisitor::visit (AST::BlockExpr &expr)
if (expander.fails_cfg_with_expand (expr.get_inner_attrs ()))
{
expr.mark_for_strip ();
- expander.pop_context ();
return;
}
diff --git a/gcc/rust/expand/rust-macro-expand.h b/gcc/rust/expand/rust-macro-expand.h
index 3c53d8d099f..a5825249f33 100644
--- a/gcc/rust/expand/rust-macro-expand.h
+++ b/gcc/rust/expand/rust-macro-expand.h
@@ -275,8 +275,11 @@ struct MacroExpander
ContextType pop_context ()
{
+ rust_assert (!context.empty ());
+
ContextType t = context.back ();
context.pop_back ();
+
return t;
}
diff --git a/gcc/testsuite/rust/compile/macro-issue1233.rs b/gcc/testsuite/rust/compile/macro-issue1233.rs
new file mode 100644
index 00000000000..d762bb7fb9e
--- /dev/null
+++ b/gcc/testsuite/rust/compile/macro-issue1233.rs
@@ -0,0 +1,22 @@
+// { dg-additional-options "-w" }
+
+macro_rules! impl_uint {
+ ($($ty:ident = $lang:literal),*) => {
+ $(
+ impl $ty {
+ pub fn to_le(self) -> Self {
+ #[cfg(not(target_endian = "little"))]
+ {
+ self
+ }
+ #[cfg(target_endian = "little")]
+ {
+ self
+ }
+ }
+ }
+ )*
+ }
+}
+
+impl_uint!(u8 = "u8", u16 = "u16", u32 = "u32");
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