refine distinct construction semantics

compiler_tests.odin

@@ -13323,6 +13323,40 @@ main func() i32 {
 	testing.expect(t, retype_count >= 5)
 }
 
+@(test)
+distinct_construction_casts_to_scalar_backing_and_infers_bound_global :: proc(t: ^testing.T) {
+	directory := "/tmp/brolang-test-distinct-construction"
+	main_path := "/tmp/brolang-test-distinct-construction/main.bro"
+	output := "/tmp/brolang-test-distinct-construction-output"
+	_ = os2.remove_all(directory)
+	defer _ = os2.remove_all(directory)
+	defer _ = os.remove(output)
+	testing.expect(t, os2.make_directory_all(directory) == nil)
+	text := `UserID :: distinct u32
+OtherID :: distinct u32
+NO_ID :: maxval!(UserID)
+Data :: union { id UserID }
+Record :: struct { data Data = Data{ id = NO_ID } }
+main func() i32 {
+	small u8 = 7
+	wide usize = 8
+	a UserID = UserID(small)
+	b UserID = UserID(wide)
+	c UserID = UserID(OtherID(9))
+	d UserID :: $UserID(usize(10))
+	record Record = {}
+	_ = record
+	if u32(a) != 7 or u32(b) != 8 or u32(c) != 9 or u32(d) != 10 { return 1 }
+	return 0
+}
+`
+	testing.expect(t, os.write_entire_file(main_path, transmute([]byte)text))
+	testing.expect_value(t, compiler_core.compile_package(directory, output), 0)
+	state := run_executable(output)
+	testing.expect_value(t, state.exit_code, 0)
+}
+
+
 @(test)
 distinct_types_reject_implicit_conversions_and_invalid_backings :: proc(t: ^testing.T) {
 	text := `Opaque :: opaque
@@ -13339,8 +13373,6 @@ main func() void {
 	id UserID = raw
 	backing u32 = UserID(2)
 	other OtherID = UserID(3)
-	narrow u8 = 4
-	_ = UserID(narrow)
 	_ = UserID()
 	_ = UserID(1, 2)
 	left UserID :: UserID(5)
@@ -13368,7 +13400,6 @@ main func() void {
 
 	invalid_backing_count := 0
 	implicit_conversion_count := 0
-	found_exact := false
 	found_arity := false
 	found_arithmetic := false
 	found_comparison := false
@@ -13376,7 +13407,6 @@ main func() void {
 	for diagnostic in diagnostics.items {
 		invalid_backing_count += 1 if strings.contains(diagnostic.message, "requires a concrete runtime backing type") else 0
 		implicit_conversion_count += 1 if strings.contains(diagnostic.message, "cannot implicitly convert") else 0
-		found_exact = found_exact || strings.contains(diagnostic.message, "requires an exact u32 value, got u8")
 		found_arity = found_arity || strings.contains(diagnostic.message, "expects 1 argument")
 		found_arithmetic = found_arithmetic || strings.contains(diagnostic.message, "arithmetic requires compatible numeric operands")
 		found_comparison = found_comparison || strings.contains(diagnostic.message, "comparison requires compatible numeric operands")
@@ -13384,7 +13414,6 @@ main func() void {
 	}
 	testing.expect_value(t, invalid_backing_count, 4)
 	testing.expect(t, implicit_conversion_count >= 3)
-	testing.expect(t, found_exact)
 	testing.expect(t, found_arity)
 	testing.expect(t, found_arithmetic)
 	testing.expect(t, found_comparison)