stage2: get rid of NameHash

Previously, stage2 used a global decl_table for all Decl objects, keyed
by a 16-byte name hash that was hopefully unique. Now, there is a tree
of Namespace objects that own their named Decl objects.

BRANCH_TODO

@@ -3,21 +3,6 @@
      their indexes starting at 0 so that we can use an array to store Sema
      results rather than a map.
 
- * get rid of NameHash
- * handle decl collision with usingnamespace
- * the decl doing the looking up needs to create a decl dependency
-   on each usingnamespace decl
- * handle usingnamespace cycles
-
- * compile error for return inside defer expression
-
- * when block has noreturn statement
-   - avoid emitting defers
-   - compile error for unreachable code
- 
- * detect `return error.Foo` and emit ZIR that unconditionally generates errdefers
- * `return`: check return operand and generate errdefers if necessary
-
  * have failed_trees and just put the file in there
    - this way we can emit all the parse errors not just the first one
    - but maybe we want just the first one?
@@ -58,13 +43,3 @@
  * repl: if you try `run` with -ofmt=c you get an access denied error because it
    tries to execute the .c file as a child process instead of executing `zig run`
    on it.
-
-=== file issues: ===
-
- * C backend: honor the exported symbol name. Right now if you do `pub fn main`
-   it generates bogus C code because the `@export` name is not honored, and it allows
-   the `main` which should be not exported, to clobber the exported symbol name.
-
- * get the test runner and `zig test` working
-   - get behavior tests passing for stage2
-

src/Compilation.zig

@@ -3563,7 +3563,6 @@ fn buildOutputFromZig(
             .handle = special_dir,
         },
         .root_src_path = src_basename,
-        .namespace_hash = Package.root_namespace_hash,
     };
     const root_name = src_basename[0 .. src_basename.len - std.fs.path.extension(src_basename).len];
     const target = comp.getTarget();

src/Module.zig

@@ -798,8 +798,6 @@ pub const Var = struct {
 pub const Scope = struct {
     tag: Tag,
 
-    pub const NameHash = [16]u8;
-
     pub fn cast(base: *Scope, comptime T: type) ?*T {
         if (base.tag != T.base_tag)
             return null;
@@ -839,7 +837,6 @@ pub const Scope = struct {
             .namespace => return @fieldParentPtr(Namespace, "base", base).file_scope.sub_file_path,
             .file => return @fieldParentPtr(File, "base", base).sub_file_path,
             .block => unreachable,
-            .decl_ref => unreachable,
         }
     }
 
@@ -861,10 +858,6 @@ pub const Scope = struct {
         /// Namespace owned by structs, enums, unions, and opaques for decls.
         namespace,
         block,
-        /// Used for simple error reporting. Only contains a reference to a
-        /// `Decl` for use with `srcDecl` and `ownerDecl`.
-        /// Has no parents or children.
-        decl_ref,
     };
 
     /// The container that structs, enums, unions, and opaques have.

src/Package.zig

@@ -11,22 +11,15 @@ const Module = @import("Module.zig");
 
 pub const Table = std.StringHashMapUnmanaged(*Package);
 
-pub const root_namespace_hash: Module.Scope.NameHash = .{
-    0, 0, 6, 6, 6, 0, 0, 0,
-    6, 9, 0, 0, 0, 4, 2, 0,
-};
-
 root_src_directory: Compilation.Directory,
 /// Relative to `root_src_directory`. May contain path separators.
 root_src_path: []const u8,
 table: Table = .{},
 parent: ?*Package = null,
-namespace_hash: Module.Scope.NameHash,
 /// Whether to free `root_src_directory` on `destroy`.
 root_src_directory_owned: bool = false,
 
 /// Allocate a Package. No references to the slices passed are kept.
-/// Don't forget to set `namespace_hash` later.
 pub fn create(
     gpa: *Allocator,
     /// Null indicates the current working directory
@@ -50,7 +43,6 @@ pub fn create(
         },
         .root_src_path = owned_src_path,
         .root_src_directory_owned = true,
-        .namespace_hash = undefined,
     };
 
     return ptr;
@@ -82,14 +74,12 @@ pub fn createWithDir(
             },
             .root_src_directory_owned = true,
             .root_src_path = owned_src_path,
-            .namespace_hash = undefined,
         };
     } else {
         ptr.* = .{
             .root_src_directory = directory,
             .root_src_directory_owned = false,
             .root_src_path = owned_src_path,
-            .namespace_hash = undefined,
         };
     }
     return ptr;
@@ -129,6 +119,5 @@ pub fn add(pkg: *Package, gpa: *Allocator, name: []const u8, package: *Package)
 pub fn addAndAdopt(parent: *Package, gpa: *Allocator, name: []const u8, child: *Package) !void {
     assert(child.parent == null); // make up your mind, who is the parent??
     child.parent = parent;
-    child.namespace_hash = std.zig.hashName(parent.namespace_hash, ":", name);
     return parent.add(gpa, name, child);
 }

src/main.zig

@@ -630,7 +630,6 @@ fn buildOutputType(
     var pkg_tree_root: Package = .{
         .root_src_directory = .{ .path = null, .handle = fs.cwd() },
         .root_src_path = &[0]u8{},
-        .namespace_hash = Package.root_namespace_hash,
     };
     defer freePkgTree(gpa, &pkg_tree_root, false);
     var cur_pkg: *Package = &pkg_tree_root;
@@ -1768,7 +1767,6 @@ fn buildOutputType(
     if (root_pkg) |pkg| {
         pkg.table = pkg_tree_root.table;
         pkg_tree_root.table = .{};
-        pkg.namespace_hash = pkg_tree_root.namespace_hash;
     }
 
     const self_exe_path = try fs.selfExePathAlloc(arena);
@@ -2657,7 +2655,6 @@ pub fn cmdBuild(gpa: *Allocator, arena: *Allocator, args: []const []const u8) !v
                 .handle = try zig_lib_directory.handle.openDir(std_special, .{}),
             },
             .root_src_path = "build_runner.zig",
-            .namespace_hash = Package.root_namespace_hash,
         };
         defer root_pkg.root_src_directory.handle.close();
 
@@ -2703,7 +2700,6 @@ pub fn cmdBuild(gpa: *Allocator, arena: *Allocator, args: []const []const u8) !v
         var build_pkg: Package = .{
             .root_src_directory = build_directory,
             .root_src_path = build_zig_basename,
-            .namespace_hash = undefined,
         };
         try root_pkg.addAndAdopt(arena, "@build", &build_pkg);
 

src/test.zig

@@ -611,7 +611,6 @@ pub const TestContext = struct {
         var root_pkg: Package = .{
             .root_src_directory = .{ .path = tmp_dir_path, .handle = tmp.dir },
             .root_src_path = tmp_src_path,
-            .namespace_hash = Package.root_namespace_hash,
         };
         defer root_pkg.table.deinit(allocator);