From ea14480246c309b8dd89537c3479e90a1bff2fd1 Mon Sep 17 00:00:00 2001
From: Stephen Gutekanst <stephen@hexops.com>
Date: Wed, 27 Mar 2024 06:14:53 -0700
Subject: [PATCH] module: improve isString, add tests

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
---
 src/module.zig | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/src/module.zig b/src/module.zig
index 7d9b0090..cb0efe78 100644
--- a/src/module.zig
+++ b/src/module.zig
@@ -817,8 +817,7 @@ fn MComponents(comptime M: anytype) type {
 fn NamespacedState(comptime modules: anytype) type {
     var fields: []const std.builtin.Type.StructField = &[0]std.builtin.Type.StructField{};
     inline for (modules) |M| {
-        // TODO: can't verify module here because it would introduce a dependency loop
-        // _ = ModuleInterface(M);
+        _ = ModuleInterface(M); // Validate the module
         const state_fields = std.meta.fields(M);
         const State = if (state_fields.len > 0) @Type(.{
             .Struct = .{
@@ -846,18 +845,37 @@ fn NamespacedState(comptime modules: anytype) type {
     });
 }
 
-// TODO: tests
-// TODO: stricter enforcement
 fn isString(comptime S: type) bool {
     return switch (@typeInfo(S)) {
-        .Pointer => |p| switch (@typeInfo(p.child)) {
-            .Array => |a| a.child == u8,
+        .Pointer => |p| switch (p.size) {
+            .Many, .Slice => p.child == u8,
+            .One => switch (@typeInfo(p.child)) {
+                .Array => |a| a.child == u8,
+                else => false,
+            },
             else => false,
         },
         else => false,
     };
 }
 
+test isString {
+    const x: [*:0]const u8 = "foobar";
+    const y: []const u8 = "foobar";
+    const z: *const [6:0]u8 = "foobar";
+    try testing.expect(bool, true).eql(isString(@TypeOf(x)));
+    try testing.expect(bool, true).eql(isString(@TypeOf(y)));
+    try testing.expect(bool, true).eql(isString(@TypeOf(z)));
+    try testing.expect(bool, true).eql(isString(@TypeOf("baz")));
+
+    const v0: []const u32 = undefined;
+    const v1: u32 = undefined;
+    const v2: *u8 = undefined;
+    try testing.expect(bool, false).eql(isString(@TypeOf(v0)));
+    try testing.expect(bool, false).eql(isString(@TypeOf(v1)));
+    try testing.expect(bool, false).eql(isString(@TypeOf(v2)));
+}
+
 test {
     testing.refAllDeclsRecursive(@This());
 }