haiku: minor fixups

 * no isHaiku() function since there is not more than one os tag that
   this applies to.
 * clean up some control flow into a switch
 * add some TODO comments to investigate panics that suspiciously look
   like they should be compile errors (see #363)

1 files changed, 35 insertions, 31 deletions

diff --git a/lib/std/Thread.zig b/lib/std/Thread.zig
index 52f625edf4..77277bd154 100644
--- a/lib/std/Thread.zig
+++ b/lib/std/Thread.zig
@@ -487,38 +487,42 @@ pub const CpuCountError = error{
 };
 
 pub fn cpuCount() CpuCountError!usize {
-    if (std.Target.current.os.tag == .linux) {
-        const cpu_set = try os.sched_getaffinity(0);
-        return @as(usize, os.CPU_COUNT(cpu_set)); // TODO should not need this usize cast
-    }
-    if (std.Target.current.os.tag == .windows) {
-        return os.windows.peb().NumberOfProcessors;
-    }
-    if (std.Target.current.os.tag == .openbsd) {
-        var count: c_int = undefined;
-        var count_size: usize = @sizeOf(c_int);
-        const mib = [_]c_int{ os.CTL_HW, os.HW_NCPUONLINE };
-        os.sysctl(&mib, &count, &count_size, null, 0) catch |err| switch (err) {
-            error.NameTooLong, error.UnknownName => unreachable,
-            else => |e| return e,
-        };
-        return @intCast(usize, count);
-    }
-    if (std.Target.current.os.tag == .haiku) {
-        var count: u32 = undefined;
-        var system_info: os.system_info = undefined;
-        const rc = os.system.get_system_info(&system_info);
-        count = system_info.cpu_count;
-        return @intCast(usize, count);
+    switch (std.Target.current.os.tag) {
+        .linux => {
+            const cpu_set = try os.sched_getaffinity(0);
+            return @as(usize, os.CPU_COUNT(cpu_set)); // TODO should not need this usize cast
+        },
+        .windows => {
+            return os.windows.peb().NumberOfProcessors;
+        },
+        .openbsd => {
+            var count: c_int = undefined;
+            var count_size: usize = @sizeOf(c_int);
+            const mib = [_]c_int{ os.CTL_HW, os.HW_NCPUONLINE };
+            os.sysctl(&mib, &count, &count_size, null, 0) catch |err| switch (err) {
+                error.NameTooLong, error.UnknownName => unreachable,
+                else => |e| return e,
+            };
+            return @intCast(usize, count);
+        },
+        .haiku => {
+            var count: u32 = undefined;
+            var system_info: os.system_info = undefined;
+            const rc = os.system.get_system_info(&system_info);
+            count = system_info.cpu_count;
+            return @intCast(usize, count);
+        },
+        else => {
+            var count: c_int = undefined;
+            var count_len: usize = @sizeOf(c_int);
+            const name = if (comptime std.Target.current.isDarwin()) "hw.logicalcpu" else "hw.ncpu";
+            os.sysctlbynameZ(name, &count, &count_len, null, 0) catch |err| switch (err) {
+                error.NameTooLong, error.UnknownName => unreachable,
+                else => |e| return e,
+            };
+            return @intCast(usize, count);
+        },
     }
-    var count: c_int = undefined;
-    var count_len: usize = @sizeOf(c_int);
-    const name = if (comptime std.Target.current.isDarwin()) "hw.logicalcpu" else "hw.ncpu";
-    os.sysctlbynameZ(name, &count, &count_len, null, 0) catch |err| switch (err) {
-        error.NameTooLong, error.UnknownName => unreachable,
-        else => |e| return e,
-    };
-    return @intCast(usize, count);
 }
 
 pub fn getCurrentThreadId() u64 {