Add length checking for tuple patterns

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-pattern.cc (TypeCheckPattern::visit):
		Add length checking for tuple patterns.
	(TypeCheckPattern::emit_pattern_size_error): New function.
	* typecheck/rust-hir-type-check-pattern.h: New function
		emit_pattern_size_error.

gcc/testsuite/ChangeLog:

	* rust/compile/tuple_mismatch.rs: New test.

Signed-off-by: Nikos Alexandris <nikos-alexandris@protonmail.com>

diff --git a/gcc/rust/typecheck/rust-hir-type-check-pattern.cc b/gcc/rust/typecheck/rust-hir-type-check-pattern.cc
index 65a3e673d953f9678943c6c207906586a9080a74..b7412bc405d5d7c48988c11fe34670692594962e 100644 (file)
--- a/gcc/rust/typecheck/rust-hir-type-check-pattern.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-pattern.cc
@@ -262,16 +262,30 @@ TypeCheckPattern::visit (HIR::TuplePattern &pattern)
          = *static_cast<HIR::TuplePatternItemsMultiple *> (
            pattern.get_items ().get ());
 
+       if (parent->get_kind () != TyTy::TUPLE)
+         {
+           rust_error_at (pattern.get_locus (), "expected %s, found tuple",
+                          parent->as_string ().c_str ());
+           break;
+         }
+
+       const auto &patterns = ref.get_patterns ();
+       size_t nitems_to_resolve = patterns.size ();
+
+       TyTy::TupleType &par = *static_cast<TyTy::TupleType *> (parent);
+       if (patterns.size () != par.get_fields ().size ())
+         {
+           emit_pattern_size_error (pattern, par.get_fields ().size (),
+                                    patterns.size ());
+           nitems_to_resolve
+             = std::min (nitems_to_resolve, par.get_fields ().size ());
+         }
+
        std::vector<TyTy::TyVar> pattern_elems;
-       for (size_t i = 0; i < ref.get_patterns ().size (); i++)
+       for (size_t i = 0; i < nitems_to_resolve; i++)
          {
-           auto &p = ref.get_patterns ()[i];
-           TyTy::BaseType *par_type = parent;
-           if (parent->get_kind () == TyTy::TUPLE)
-             {
-               TyTy::TupleType &par = *static_cast<TyTy::TupleType *> (parent);
-               par_type = par.get_field (i);
-             }
+           auto &p = patterns[i];
+           TyTy::BaseType *par_type = par.get_field (i);
 
            TyTy::BaseType *elem
              = TypeCheckPattern::Resolve (p.get (), par_type);
@@ -407,5 +421,21 @@ TypeCheckPattern::visit (HIR::SlicePattern &pattern)
                 "type checking qualified path patterns not supported");
 }
 
+void
+TypeCheckPattern::emit_pattern_size_error (const HIR::Pattern &pattern,
+                                          size_t expected_field_count,
+                                          size_t got_field_count)
+{
+  RichLocation r (pattern.get_locus ());
+  r.add_range (mappings->lookup_location (parent->get_ref ()));
+  rust_error_at (r,
+                "expected a tuple with %lu %s, found one "
+                "with %lu %s",
+                (unsigned long) expected_field_count,
+                expected_field_count == 1 ? "element" : "elements",
+                (unsigned long) got_field_count,
+                got_field_count == 1 ? "element" : "elements");
+}
+
 } // namespace Resolver
 } // namespace Rust

diff --git a/gcc/rust/typecheck/rust-hir-type-check-pattern.h b/gcc/rust/typecheck/rust-hir-type-check-pattern.h
index e7550071548cf4f883ac697cfade25a2ea989a16..a4fbf888213d1eb4711b9c4661debb593c4b837d 100644 (file)
--- a/gcc/rust/typecheck/rust-hir-type-check-pattern.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-pattern.h
@@ -51,6 +51,10 @@ private:
                                 Analysis::NodeMapping mappings,
                                 Location locus);
 
+  void emit_pattern_size_error (const HIR::Pattern &pattern,
+                               size_t expected_field_count,
+                               size_t got_field_count);
+
   TyTy::BaseType *parent;
   TyTy::BaseType *infered;
 };

diff --git a/gcc/testsuite/rust/compile/tuple_mismatch.rs b/gcc/testsuite/rust/compile/tuple_mismatch.rs
new file mode 100644 (file)
index 0000000..fbeb4b2
--- /dev/null
+++ b/gcc/testsuite/rust/compile/tuple_mismatch.rs
@@ -0,0 +1,13 @@
+fn main() {
+    let (_,) = 1; // { dg-error "expected <integer>, found tuple" }
+    let (_,) = (1, 2); // { dg-error "expected a tuple with 2 elements, found one with 1 element" }
+    let (_, _) = (1, 2, 3); // { dg-error "expected a tuple with 3 elements, found one with 2 elements" }
+    let (_, _) = (1,); // { dg-error "expected a tuple with 1 element, found one with 2 elements" }
+}
+
+// The lhs and rhs sizes don't match, but we still resolve 'a' to be bool, we don't
+// error out immediately once we notice the size mismatch.
+fn foo() -> i32 { // { dg-error "expected .i32. got .bool." }
+    let (a, _) = (true, 2, 3); // { dg-error "expected a tuple with 3 elements, found one with 2 elements" }
+    a
+}