remove usingnamespace from the language

closes #20663

Author: andrewrk

doc/langref.html.in

@@ -3842,37 +3842,6 @@ void do_a_thing(struct Foo *foo) {
       {#header_close#}
       {#header_close#}
 
-      {#header_open|usingnamespace#}
-      <p>
-      {#syntax#}usingnamespace{#endsyntax#} is a declaration that mixes all the public
-      declarations of the operand, which must be a {#link|struct#}, {#link|union#}, {#link|enum#},
-      or {#link|opaque#}, into the namespace:
-      </p>
-      {#code|test_usingnamespace.zig#}
-
-      <p>
-      {#syntax#}usingnamespace{#endsyntax#} has an important use case when organizing the public
-      API of a file or package. For example, one might have <code class="file">c.zig</code> with all of the
-      {#link|C imports|Import from C Header File#}:
-      </p>
-      {#syntax_block|zig|c.zig#}
-pub usingnamespace @cImport({
-    @cInclude("epoxy/gl.h");
-    @cInclude("GLFW/glfw3.h");
-    @cDefine("STBI_ONLY_PNG", "");
-    @cDefine("STBI_NO_STDIO", "");
-    @cInclude("stb_image.h");
-});
-      {#end_syntax_block#}
-      <p>
-      The above example demonstrates using {#syntax#}pub{#endsyntax#} to qualify the
-      {#syntax#}usingnamespace{#endsyntax#} additionally makes the imported declarations
-      {#syntax#}pub{#endsyntax#}. This can be used to forward declarations, giving precise control
-      over what declarations a given file exposes.
-      </p>
-      {#header_close#}
-
-
       {#header_open|comptime#}
       <p>
       Zig places importance on the concept of whether an expression is known at compile-time.
@@ -6545,7 +6514,7 @@ fn cmpxchgWeakButNotAtomic(comptime T: type, ptr: *T, expected_value: T, new_val
       </p>
       <ul>
         <li>If a call to {#syntax#}@import{#endsyntax#} is analyzed, the file being imported is analyzed.</li>
-        <li>If a type (including a file) is analyzed, all {#syntax#}comptime{#endsyntax#}, {#syntax#}usingnamespace{#endsyntax#}, and {#syntax#}export{#endsyntax#} declarations within it are analyzed.</li>
+        <li>If a type (including a file) is analyzed, all {#syntax#}comptime{#endsyntax#} and {#syntax#}export{#endsyntax#} declarations within it are analyzed.</li>
         <li>If a type (including a file) is analyzed, and the compilation is for a {#link|test|Zig Test#}, and the module the type is within is the root module of the compilation, then all {#syntax#}test{#endsyntax#} declarations within it are also analyzed.</li>
         <li>If a reference to a named declaration (i.e. a usage of it) is analyzed, the declaration being referenced is analyzed. Declarations are order-independent, so this reference may be above or below the declaration being referenced, or even in another file entirely.</li>
       </ul>
@@ -7782,18 +7751,6 @@ fn readU32Be() u32 {}
             </ul>
           </td>
         </tr>
-        <tr>
-          <th scope="row">
-            <pre>{#syntax#}usingnamespace{#endsyntax#}</pre>
-          </th>
-          <td>
-            {#syntax#}usingnamespace{#endsyntax#} is a top-level declaration that imports all the public declarations of the operand,
-            which must be a struct, union, or enum, into the current scope.
-            <ul>
-              <li>See also {#link|usingnamespace#}</li>
-            </ul>
-          </td>
-        </tr>
         <tr>
           <th scope="row">
             <pre>{#syntax#}var{#endsyntax#}</pre>
@@ -7863,7 +7820,6 @@ ComptimeDecl <- KEYWORD_comptime Block
 Decl
     <- (KEYWORD_export / KEYWORD_extern STRINGLITERALSINGLE? / KEYWORD_inline / KEYWORD_noinline)? FnProto (SEMICOLON / Block)
      / (KEYWORD_export / KEYWORD_extern STRINGLITERALSINGLE?)? KEYWORD_threadlocal? GlobalVarDecl
-     / KEYWORD_usingnamespace Expr SEMICOLON
 
 FnProto <- KEYWORD_fn IDENTIFIER? LPAREN ParamDeclList RPAREN ByteAlign? AddrSpace? LinkSection? CallConv? EXCLAMATIONMARK? TypeExpr
 
@@ -8408,7 +8364,6 @@ KEYWORD_threadlocal <- 'threadlocal' end_of_word
 KEYWORD_try         <- 'try'         end_of_word
 KEYWORD_union       <- 'union'       end_of_word
 KEYWORD_unreachable <- 'unreachable' end_of_word
-KEYWORD_usingnamespace <- 'usingnamespace' end_of_word
 KEYWORD_var         <- 'var'         end_of_word
 KEYWORD_volatile    <- 'volatile'    end_of_word
 KEYWORD_while       <- 'while'       end_of_word
@@ -8424,7 +8379,7 @@ keyword <- KEYWORD_addrspace / KEYWORD_align / KEYWORD_allowzero / KEYWORD_and
          / KEYWORD_pub / KEYWORD_resume / KEYWORD_return / KEYWORD_linksection
          / KEYWORD_struct / KEYWORD_suspend / KEYWORD_switch / KEYWORD_test
          / KEYWORD_threadlocal / KEYWORD_try / KEYWORD_union / KEYWORD_unreachable
-         / KEYWORD_usingnamespace / KEYWORD_var / KEYWORD_volatile / KEYWORD_while
+         / KEYWORD_var / KEYWORD_volatile / KEYWORD_while
       {#end_syntax_block#}
       {#header_close#}
       {#header_open|Zen#}

doc/langref/test_usingnamespace.zig

@@ -160,12 +160,6 @@ fn walkMember(w: *Walk, decl: Ast.Node.Index) Error!void {
             try walkExpression(w, decl);
         },
 
-        .@"usingnamespace" => {
-            try w.transformations.append(.{ .delete_node = decl });
-            const expr = ast.nodeData(decl).node;
-            try walkExpression(w, expr);
-        },
-
         .global_var_decl,
         .local_var_decl,
         .simple_var_decl,
@@ -520,7 +514,6 @@ fn walkExpression(w: *Walk, node: Ast.Node.Index) Error!void {
         .local_var_decl => unreachable,
         .simple_var_decl => unreachable,
         .aligned_var_decl => unreachable,
-        .@"usingnamespace" => unreachable,
         .test_decl => unreachable,
         .asm_output => unreachable,
         .asm_input => unreachable,

lib/compiler/reduce/Walk.zig

@@ -567,7 +567,6 @@ fn struct_decl(
         },
 
         .@"comptime",
-        .@"usingnamespace",
         => try w.expr(&namespace.base, parent_decl, ast.nodeData(member).node),
 
         .test_decl => try w.expr(&namespace.base, parent_decl, ast.nodeData(member).opt_token_and_node[1]),
@@ -639,7 +638,6 @@ fn expr(w: *Walk, scope: *Scope, parent_decl: Decl.Index, node: Ast.Node.Index)
     const ast = w.file.get_ast();
     switch (ast.nodeTag(node)) {
         .root => unreachable, // Top-level declaration.
-        .@"usingnamespace" => unreachable, // Top-level declaration.
         .test_decl => unreachable, // Top-level declaration.
         .container_field_init => unreachable, // Top-level declaration.
         .container_field_align => unreachable, // Top-level declaration.

lib/docs/wasm/Walk.zig

@@ -137,7 +137,6 @@ pub fn fileSourceHtml(
             .keyword_try,
             .keyword_union,
             .keyword_unreachable,
-            .keyword_usingnamespace,
             .keyword_var,
             .keyword_volatile,
             .keyword_allowzero,

lib/docs/wasm/html_render.zig

@@ -755,13 +755,6 @@ pub fn firstToken(tree: Ast, node: Node.Index) TokenIndex {
             return i - end_offset;
         },
 
-        .@"usingnamespace" => {
-            const main_token: TokenIndex = tree.nodeMainToken(n);
-            const has_visib_token = tree.isTokenPrecededByTags(main_token, &.{.keyword_pub});
-            end_offset += @intFromBool(has_visib_token);
-            return main_token - end_offset;
-        },
-
         .container_field_init,
         .container_field_align,
         .container_field,
@@ -881,7 +874,6 @@ pub fn lastToken(tree: Ast, node: Node.Index) TokenIndex {
     while (true) switch (tree.nodeTag(n)) {
         .root => return @intCast(tree.tokens.len - 1),
 
-        .@"usingnamespace",
         .bool_not,
         .negation,
         .bit_not,
@@ -3033,12 +3025,6 @@ pub const Node = struct {
         ///
         /// The `main_token` field is the first token for the source file.
         root,
-        /// `usingnamespace expr;`.
-        ///
-        /// The `data` field is a `.node` to expr.
-        ///
-        /// The `main_token` field is the `usingnamespace` token.
-        @"usingnamespace",
         /// `test {}`,
         /// `test "name" {}`,
         /// `test identifier {}`.

lib/std/zig/Ast.zig

@@ -442,7 +442,6 @@ fn lvalExpr(gz: *GenZir, scope: *Scope, node: Ast.Node.Index) InnerError!Zir.Ins
     const tree = astgen.tree;
     switch (tree.nodeTag(node)) {
         .root => unreachable,
-        .@"usingnamespace" => unreachable,
         .test_decl => unreachable,
         .global_var_decl => unreachable,
         .local_var_decl => unreachable,
@@ -637,7 +636,6 @@ fn expr(gz: *GenZir, scope: *Scope, ri: ResultInfo, node: Ast.Node.Index) InnerE
 
     switch (tree.nodeTag(node)) {
         .root => unreachable, // Top-level declaration.
-        .@"usingnamespace" => unreachable, // Top-level declaration.
         .test_decl => unreachable, // Top-level declaration.
         .container_field_init => unreachable, // Top-level declaration.
         .container_field_align => unreachable, // Top-level declaration.
@@ -4700,69 +4698,6 @@ fn comptimeDecl(
     });
 }
 
-fn usingnamespaceDecl(
-    astgen: *AstGen,
-    gz: *GenZir,
-    scope: *Scope,
-    wip_members: *WipMembers,
-    node: Ast.Node.Index,
-) InnerError!void {
-    const tree = astgen.tree;
-
-    const old_hasher = astgen.src_hasher;
-    defer astgen.src_hasher = old_hasher;
-    astgen.src_hasher = std.zig.SrcHasher.init(.{});
-    astgen.src_hasher.update(tree.getNodeSource(node));
-    astgen.src_hasher.update(std.mem.asBytes(&astgen.source_column));
-
-    const type_expr = tree.nodeData(node).node;
-    const is_pub = tree.isTokenPrecededByTags(tree.nodeMainToken(node), &.{.keyword_pub});
-
-    // Up top so the ZIR instruction index marks the start range of this
-    // top-level declaration.
-    const decl_inst = try gz.makeDeclaration(node);
-    wip_members.nextDecl(decl_inst);
-    astgen.advanceSourceCursorToNode(node);
-
-    // This is just needed for the `setDeclaration` call.
-    var dummy_gz = gz.makeSubBlock(scope);
-    defer dummy_gz.unstack();
-
-    var usingnamespace_gz: GenZir = .{
-        .is_comptime = true,
-        .decl_node_index = node,
-        .decl_line = astgen.source_line,
-        .parent = scope,
-        .astgen = astgen,
-        .instructions = gz.instructions,
-        .instructions_top = gz.instructions.items.len,
-    };
-    defer usingnamespace_gz.unstack();
-
-    const decl_column = astgen.source_column;
-
-    const namespace_inst = try typeExpr(&usingnamespace_gz, &usingnamespace_gz.base, type_expr);
-    _ = try usingnamespace_gz.addBreak(.break_inline, decl_inst, namespace_inst);
-
-    var hash: std.zig.SrcHash = undefined;
-    astgen.src_hasher.final(&hash);
-    try setDeclaration(decl_inst, .{
-        .src_hash = hash,
-        .src_line = usingnamespace_gz.decl_line,
-        .src_column = decl_column,
-        .kind = .@"usingnamespace",
-        .name = .empty,
-        .is_pub = is_pub,
-        .is_threadlocal = false,
-        .linkage = .normal,
-        .type_gz = &dummy_gz,
-        .align_gz = &dummy_gz,
-        .linksection_gz = &dummy_gz,
-        .addrspace_gz = &dummy_gz,
-        .value_gz = &usingnamespace_gz,
-    });
-}
-
 fn testDecl(
     astgen: *AstGen,
     gz: *GenZir,
@@ -5932,23 +5867,6 @@ fn containerMember(
                 },
             };
         },
-        .@"usingnamespace" => {
-            const prev_decl_index = wip_members.decl_index;
-            astgen.usingnamespaceDecl(gz, scope, wip_members, member_node) catch |err| switch (err) {
-                error.OutOfMemory => return error.OutOfMemory,
-                error.AnalysisFail => {
-                    wip_members.decl_index = prev_decl_index;
-                    try addFailedDeclaration(
-                        wip_members,
-                        gz,
-                        .@"usingnamespace",
-                        .empty,
-                        member_node,
-                        tree.isTokenPrecededByTags(tree.nodeMainToken(member_node), &.{.keyword_pub}),
-                    );
-                },
-            };
-        },
         .test_decl => {
             const prev_decl_index = wip_members.decl_index;
             // We need to have *some* decl here so that the decl count matches what's expected.
@@ -10398,7 +10316,6 @@ fn nodeMayEvalToError(tree: *const Ast, start_node: Ast.Node.Index) BuiltinFn.Ev
     while (true) {
         switch (tree.nodeTag(node)) {
             .root,
-            .@"usingnamespace",
             .test_decl,
             .switch_case,
             .switch_case_inline,
@@ -10606,7 +10523,6 @@ fn nodeImpliesMoreThanOnePossibleValue(tree: *const Ast, start_node: Ast.Node.In
     while (true) {
         switch (tree.nodeTag(node)) {
             .root,
-            .@"usingnamespace",
             .test_decl,
             .switch_case,
             .switch_case_inline,
@@ -10845,7 +10761,6 @@ fn nodeImpliesComptimeOnly(tree: *const Ast, start_node: Ast.Node.Index) bool {
     while (true) {
         switch (tree.nodeTag(node)) {
             .root,
-            .@"usingnamespace",
             .test_decl,
             .switch_case,
             .switch_case_inline,
@@ -13518,7 +13433,7 @@ fn scanContainer(
                 break :blk .{ .decl, ident };
             },
 
-            .@"comptime", .@"usingnamespace" => {
+            .@"comptime" => {
                 decl_count += 1;
                 continue;
             },
@@ -13896,7 +13811,6 @@ const DeclarationName = union(enum) {
     decltest: Ast.TokenIndex,
     unnamed_test,
     @"comptime",
-    @"usingnamespace",
 };
 
 fn addFailedDeclaration(
@@ -13986,7 +13900,6 @@ fn setDeclaration(
         .@"test" => .@"test",
         .decltest => .decltest,
         .@"comptime" => .@"comptime",
-        .@"usingnamespace" => if (args.is_pub) .pub_usingnamespace else .@"usingnamespace",
         .@"const" => switch (args.linkage) {
             .normal => if (args.is_pub) id: {
                 if (has_special_body) break :id .pub_const;

lib/std/zig/AstGen.zig

@@ -165,10 +165,6 @@ fn expr(astrl: *AstRlAnnotate, node: Ast.Node.Index, block: ?*Block, ri: ResultI
             }
             return false;
         },
-        .@"usingnamespace" => {
-            _ = try astrl.expr(tree.nodeData(node).node, block, ResultInfo.type_only);
-            return false;
-        },
         .test_decl => {
             _ = try astrl.expr(tree.nodeData(node).opt_token_and_node[1], block, ResultInfo.none);
             return false;