Remove matchtag use from SwitchStmt.

Author: dvander

compiler/semantics.cpp

@@ -2762,7 +2762,7 @@ bool Semantics::CheckSwitchStmt(SwitchStmt* stmt) {
             }
             if (tag_ok) {
                 AutoErrorPos aep(expr->pos());
-                matchtag(v.type(), type, MATCHTAG_COERCE);
+                TypeChecker::DoCoerce(expr->pos(), v.type(), type);
             }
 
             if (!case_values.count(value))

tests/compile-only/warn-switch-tag-mismatch.sp renamed to tests/compile-only/fail-switch-tag-mismatch.sp

@@ -0,0 +1,3 @@
+tests/compile-only/fail-switch-tag-mismatch.sp(21) : error 450: no viable conversion from "Bar" to "Foo"
+tests/compile-only/fail-switch-tag-mismatch.sp(22) : warning 253: implicit conversion from "int" to "Foo" is undefined
+tests/compile-only/fail-switch-tag-mismatch.sp(23) : error 450: no viable conversion from "float" to "Foo"