Change the doc to mention only gpu or ref as targets (#1153)

Documentation update for valid targets

doc/src/reference/py.rst

@@ -121,7 +121,7 @@ target
 
     Constructs the target.
 
-    :param str name: The name of the target to construct. This can either be 'cpu' or 'gpu'.
+    :param str name: The name of the target to construct. This can either be 'gpu' or 'ref'.
 
     :rtype: target
 

src/register_target.cpp

-#include <migraphx/register_target.hpp>
 #include <unordered_map>
+#include <migraphx/register_target.hpp>
 
 namespace migraphx {
 inline namespace MIGRAPHX_INLINE_NS {
@@ -11,7 +11,17 @@ std::unordered_map<std::string, target>& target_map()
 }
 
 void register_target(const target& t) { target_map()[t.name()] = t; }
-target make_target(const std::string& name) { return target_map().at(name); }
+
+target make_target(const std::string& name)
+{
+    const auto it = target_map().find(name);
+    if(it == target_map().end())
+    {
+        MIGRAPHX_THROW("Requested target '" + name + "' is not enabled or not supported");
+    }
+    return it->second;
+}
+
 std::vector<std::string> get_targets()
 {
     std::vector<std::string> result;

test/targets.cpp

@@ -12,6 +12,11 @@ TEST_CASE(make_target)
     }
 }
 
+TEST_CASE(make_invalid_target)
+{
+    EXPECT(test::throws([&] { migraphx::make_target("mi100"); }));
+}
+
 TEST_CASE(targets)
 {
     auto ts = migraphx::get_targets();