some explicit errors in function signatures

src/sections.zig

@@ -42,16 +42,11 @@ const Corpus = struct {
     groupname2users: StringHashMap([]*const User),
     username2groups: StringHashMap([]*const Group),
 
-    pub const initErr = Allocator.Error ||
-        error{InvalidUtf8} ||
-        error{Duplicate} ||
-        error{NotFound};
-
     pub fn init(
         baseAllocator: Allocator,
         usersConst: []const User,
         groupsConst: []const Group,
-    ) initErr!Corpus {
+    ) error{ OutOfMemory, InvalidUtf8, Duplicate, NotFound }!Corpus {
         var arena = std.heap.ArenaAllocator.init(baseAllocator);
         var allocator = arena.allocator();
         errdefer arena.deinit();
@@ -196,11 +191,10 @@ pub fn bdzUsername(allocator: Allocator, corpus: *const Corpus) cmph.Error![]con
 // - shell module should accept a list of shells and spit out two slices
 // (allocated with a given allocator). There is too much dancing around
 // here.
-const shellSectionsErr = Allocator.Error || error{Overflow};
 pub fn shellSections(
     allocator: Allocator,
     corpus: *const Corpus,
-) shellSectionsErr!ShellSections {
+) error{ OutOfMemory, Overflow }!ShellSections {
     var popcon = shellImport.ShellWriter.init(allocator);
     for (corpus.usersMulti.items(.shell)) |shell| {
         try popcon.put(shell);
@@ -227,8 +221,10 @@ pub const UserGids = struct {
 
 const userGidsPaddingBits = 3;
 
-const userGidsErr = Allocator.Error || error{Overflow};
-pub fn userGids(allocator: Allocator, corpus: *const Corpus) userGidsErr!UserGids {
+pub fn userGids(
+    allocator: Allocator,
+    corpus: *const Corpus,
+) error{ OutOfMemory, Overflow }!UserGids {
     var blob = ArrayList(u8).init(allocator);
     errdefer blob.deinit();
     var name2offset = StringHashMap(u32).init(allocator);
@@ -287,7 +283,10 @@ pub fn usersSection(
     return buf.toOwnedSlice();
 }
 
-pub fn groupMembers(allocator: Allocator, corpus: *const Corpus) Allocator.Error!void {
+pub fn groupMembers(
+    allocator: Allocator,
+    corpus: *const Corpus,
+) error{OutOfMemory}!void {
     var buf: [compress.maxVarintLen64]u8 = undefined;
     var offsets = ArrayListUnmanaged(usize).initCapacity(
         allocator,