[COMMITTED 18/25] gccrs: fix bug in pattern check for tuples

[arthur . cohen]

From: Philip Herron <herron.phi...@googlemail.com>

We can point to generic parent types which means we need to do the shallow
resolve thing that rustc does. We have destructure which is similar to get
what the parameter type points to.

Fixes #2775

gcc/rust/ChangeLog:

        * typecheck/rust-hir-type-check-pattern.cc (TypeCheckPattern::visit): 
use destructure

gcc/testsuite/ChangeLog:

        * rust/compile/issue-2775.rs: New test.

Signed-off-by: Philip Herron <herron.phi...@googlemail.com>
---
 gcc/rust/typecheck/rust-hir-type-check-pattern.cc |  6 ++++--
 gcc/testsuite/rust/compile/issue-2775.rs          | 11 +++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/rust/compile/issue-2775.rs

diff --git a/gcc/rust/typecheck/rust-hir-type-check-pattern.cc 
b/gcc/rust/typecheck/rust-hir-type-check-pattern.cc
index 19f742f2154..c7f29e28b2d 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-pattern.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-pattern.cc
@@ -302,7 +302,8 @@ TypeCheckPattern::visit (HIR::TuplePattern &pattern)
          = *static_cast<HIR::TuplePatternItemsMultiple *> (
            pattern.get_items ().get ());
 
-       if (parent->get_kind () != TyTy::TUPLE)
+       auto resolved_parent = parent->destructure ();
+       if (resolved_parent->get_kind () != TyTy::TUPLE)
          {
            rust_error_at (pattern.get_locus (), "expected %s, found tuple",
                           parent->as_string ().c_str ());
@@ -312,7 +313,8 @@ TypeCheckPattern::visit (HIR::TuplePattern &pattern)
        const auto &patterns = ref.get_patterns ();
        size_t nitems_to_resolve = patterns.size ();
 
-       TyTy::TupleType &par = *static_cast<TyTy::TupleType *> (parent);
+       TyTy::TupleType &par
+         = *static_cast<TyTy::TupleType *> (resolved_parent);
        if (patterns.size () != par.get_fields ().size ())
          {
            emit_pattern_size_error (pattern, par.get_fields ().size (),
diff --git a/gcc/testsuite/rust/compile/issue-2775.rs 
b/gcc/testsuite/rust/compile/issue-2775.rs
new file mode 100644
index 00000000000..3ad7085785e
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-2775.rs
@@ -0,0 +1,11 @@
+// { dg-options "-w" }
+#[lang = "sized"]
+pub trait Sized {}
+
+struct Ref<'a, T> {
+    x: &'a T,
+}
+
+pub fn test<'a, 'b, 'c>() {
+    let (_, &&Ref::<(&'_ i32, i32)> { x: &(a, b) }): (i32, &'_ &'b Ref<'b, 
(&'c i32, i32)>);
+}
-- 
2.42.1