Move the ir test (#5510)

This test has its own directory, since #3056. We haven't added any more,
so fold it into basics. Also simplify it a little using `else`, and
`no_prelude`.

Note, I'm not even sure how much we need this test given the
`%.loc<line>_<col>`, but I feel slightly worse deleting it.

Author: jonmeow

toolchain/check/testdata/basics/no_prelude/duplicate_name_same_line.carbon

@@ -0,0 +1,63 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// EXTRA-ARGS: --dump-sem-ir-ranges=only
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/basics/no_prelude/duplicate_name_same_line.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/basics/no_prelude/duplicate_name_same_line.carbon
+
+fn A() {
+  if (true) {
+    // This declares `n` in two different scopes, it's just showing the IR
+    // behavior of having both on the same line.
+    //@dump-sem-ir-begin
+    var n: (); } else { var n: ();
+    //@dump-sem-ir-end
+  }
+}
+
+// CHECK:STDOUT: --- duplicate_name_same_line.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %pattern_type: type = pattern_type %empty_tuple.type [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @A() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !if.then:
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %n.patt.loc18_9: %pattern_type = binding_pattern n [concrete]
+// CHECK:STDOUT:     %n.var_patt.loc18_5: %pattern_type = var_pattern %n.patt.loc18_9 [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %n.var.loc18_5: ref %empty_tuple.type = var %n.var_patt.loc18_5
+// CHECK:STDOUT:   %.loc18_13.1: type = splice_block %.loc18_13.3 [concrete = constants.%empty_tuple.type] {
+// CHECK:STDOUT:     %.loc18_13.2: %empty_tuple.type = tuple_literal ()
+// CHECK:STDOUT:     %.loc18_13.3: type = converted %.loc18_13.2, constants.%empty_tuple.type [concrete = constants.%empty_tuple.type]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %n.loc18_9: ref %empty_tuple.type = bind_name n, %n.var.loc18_5
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !if.else:
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %n.patt.loc18_29: %pattern_type = binding_pattern n [concrete]
+// CHECK:STDOUT:     %n.var_patt.loc18_25: %pattern_type = var_pattern %n.patt.loc18_29 [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %n.var.loc18_25: ref %empty_tuple.type = var %n.var_patt.loc18_25
+// CHECK:STDOUT:   %.loc18_33.1: type = splice_block %.loc18_33.3 [concrete = constants.%empty_tuple.type] {
+// CHECK:STDOUT:     %.loc18_33.2: %empty_tuple.type = tuple_literal ()
+// CHECK:STDOUT:     %.loc18_33.3: type = converted %.loc18_33.2, constants.%empty_tuple.type [concrete = constants.%empty_tuple.type]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %n.loc18_29: ref %empty_tuple.type = bind_name n, %n.var.loc18_25
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:
+// CHECK:STDOUT: !if.done:
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT: