From: Aiman Najjar <[email protected]>
Fixes Rust-GCC/gccrs#4747
Update logic so unused collector tracks the usage of only the last
assignment for a given variable. When a new assignment is encountered
before last one is used, move the prior assignment to a new
unused_assigns set.
gcc/rust/ChangeLog:
* checks/lints/unused/rust-unused-checker.cc
(UnusedChecker::visit): Update logic for checking unused
assignments.
* checks/lints/unused/rust-unused-context.cc
(UnusedContext::add_assign): Use new set to track unused
assignments.
(UnusedContext::remove_assign): Update to track only last
assignment.
(UnusedContext::is_variable_assigned): Likewise.
(UnusedContext::is_assign_unused): New helper function to
check if given id was marked as unused by collector.
* checks/lints/unused/rust-unused-context.h:
(class UnusedContext): Add new set to track unused assignments and
changed current structure to track only last assignment per
variable (one to one map).
gcc/testsuite/ChangeLog:
* rust/compile/issue-4747.rs: New test.
Signed-off-by: Aiman Najjar <[email protected]>
---
This change was merged into the gccrs repository and is posted here for
upstream visibility and potential drive-by review, as requested by GCC
release managers.
Each commit email contains a link to its details on github from where you can
find the Pull-Request and associated discussions.
Commit on github: https://github.com/Rust-GCC/gccrs/commit/7a0c8beaa0c2cdd5607e561edeeebee196277ad9
The commit has been mentioned in the following issue(s):
- Rust-GCC/gccrs#4747: https://github.com/Rust-GCC/gccrs/issues/4747
The commit has been mentioned in the following pull-request(s):
- https://github.com/Rust-GCC/gccrs/pull/4756
.../lints/unused/rust-unused-checker.cc | 17 +++------
.../lints/unused/rust-unused-context.cc | 21 +++++------
.../checks/lints/unused/rust-unused-context.h | 6 ++--
gcc/testsuite/rust/compile/issue-4747.rs | 36 +++++++++++++++++++
4 files changed, 55 insertions(+), 25 deletions(-)
create mode 100644 gcc/testsuite/rust/compile/issue-4747.rs
diff --git a/gcc/rust/checks/lints/unused/rust-unused-checker.cc b/gcc/rust/checks/lints/unused/rust-unused-checker.cc
index 1c128f519..c9c906338 100644
--- a/gcc/rust/checks/lints/unused/rust-unused-checker.cc
+++ b/gcc/rust/checks/lints/unused/rust-unused-checker.cc
@@ -105,19 +105,10 @@ UnusedChecker::visit (HIR::AssignmentExpr &expr)
{
const auto &lhs = expr.get_lhs ();
auto var_name = lhs.to_string ();
- NodeId ast_node_id = lhs.get_mappings ().get_nodeid ();
- if (auto def_id
- = nr_context.lookup (ast_node_id, Resolver2_0::Namespace::Values))
- {
- if (auto id = mappings.lookup_node_to_hir (*def_id))
- {
- if (unused_context.is_variable_assigned (
- *id, lhs.get_mappings ().get_hirid ())
- && var_name[0] != '_')
- rust_warning_at (lhs.get_locus (), OPT_Wunused_variable,
- "unused assignment %qs", var_name.c_str ());
- }
- }
+ if (var_name[0] != '_'
+ && unused_context.is_assign_unused (lhs.get_mappings ().get_hirid ()))
+ rust_warning_at (lhs.get_locus (), OPT_Wunused_variable,
+ "unused assignment %qs", var_name.c_str ());
}
void
diff --git a/gcc/rust/checks/lints/unused/rust-unused-context.cc b/gcc/rust/checks/lints/unused/rust-unused-context.cc
index 8a68a601a..ff7f25ac9 100644
--- a/gcc/rust/checks/lints/unused/rust-unused-context.cc
+++ b/gcc/rust/checks/lints/unused/rust-unused-context.cc
@@ -37,27 +37,28 @@ UnusedContext::is_variable_used (HirId id) const
void
UnusedContext::add_assign (HirId id_def, HirId id)
{
- assigned_vars[id_def].push_back (id);
+ if (is_variable_assigned (id_def))
+ unused_assigns.emplace (assigned_vars[id_def]);
+ assigned_vars[id_def] = id;
}
void
UnusedContext::remove_assign (HirId id_def)
{
if (assigned_vars.find (id_def) != assigned_vars.end ())
- {
- assigned_vars[id_def].pop_back ();
+ assigned_vars.erase (id_def);
+}
- if (assigned_vars[id_def].empty ())
- assigned_vars.erase (id_def);
- }
+bool
+UnusedContext::is_variable_assigned (HirId id_def)
+{
+ return assigned_vars.find (id_def) != assigned_vars.end ();
}
bool
-UnusedContext::is_variable_assigned (HirId id_def, HirId id)
+UnusedContext::is_assign_unused (HirId id)
{
- auto assigned_vec = assigned_vars[id_def];
- return std::find (assigned_vec.begin (), assigned_vec.end (), id)
- != assigned_vec.end ();
+ return unused_assigns.find (id) != unused_assigns.end ();
}
void
diff --git a/gcc/rust/checks/lints/unused/rust-unused-context.h b/gcc/rust/checks/lints/unused/rust-unused-context.h
index 1405ebb64..9dd589759 100644
--- a/gcc/rust/checks/lints/unused/rust-unused-context.h
+++ b/gcc/rust/checks/lints/unused/rust-unused-context.h
@@ -31,7 +31,8 @@ public:
// Assigned var
void add_assign (HirId id_def, HirId id);
void remove_assign (HirId id_def);
- bool is_variable_assigned (HirId id_def, HirId id);
+ bool is_variable_assigned (HirId id_ref);
+ bool is_assign_unused (HirId id);
// Mutable var
void add_mut (HirId id);
@@ -47,7 +48,8 @@ public:
private:
std::unordered_set<HirId> used_vars;
std::unordered_set<HirId> mutable_vars;
- std::map<HirId, std::vector<HirId>> assigned_vars;
+ std::map<HirId, HirId> assigned_vars;
+ std::unordered_set<HirId> unused_assigns;
std::unordered_set<HirId> used_labels;
};
diff --git a/gcc/testsuite/rust/compile/issue-4747.rs b/gcc/testsuite/rust/compile/issue-4747.rs
new file mode 100644
index 000000000..7b1f28e81
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-4747.rs
@@ -0,0 +1,36 @@
+// { dg-additional-options "-frust-unused-check-2.0" }
+#![feature(no_core)]
+#![no_core]
+fn foo(mut n: i32) {
+ if false {
+ n = 1i32;
+ // { dg-warning "unused assignment .n." "" { target *-*-* } .-1 }
+ }
+
+ n = 1i32;
+ // { dg-warning "unused assignment .n." "" { target *-*-* } .-1 }
+
+ n = 2i32;
+ bar(n);
+
+ if n > 0i32 {
+ let _ = 1i32 / n;
+ }
+ let _ = 1i32 / n;
+
+ let mut n;
+
+ n = 10;
+ // { dg-warning "unused assignment .n." "" { target *-*-* } .-1 }
+
+ n = 5;
+ if n > 0 {
+ let _ = 1i32 / n;
+ }
+}
+
+fn bar(_n: i32) {}
+
+fn main() {
+ foo(1);
+}
base-commit: 016d4b958629cf944231fc56d6a4699d30f06467
--
2.54.0
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