Complete errors

Author: psznm

src/analysis.zig

@@ -4754,7 +4754,7 @@ pub const PositionContext = union(enum) {
     /// XXX: Internal use only, currently points to the loc of the first l_paren
     parens_expr: offsets.Loc,
     keyword: Ast.TokenIndex,
-    error_access,
+    error_access: offsets.Loc,
     comment,
     other,
     empty,
@@ -5100,7 +5100,7 @@ pub fn getPositionContext(
                 stack.pop(curr_ctx.scope == .braces);
                 continue;
             },
-            .keyword_error => .error_access,
+            .keyword_error => .{ .error_access = tok.loc },
             .number_literal => {
                 if (tok.loc.start <= source_index and tok.loc.end >= source_index) {
                     return .{ .number_literal = tok.loc };

src/features/completions.zig

@@ -731,6 +731,50 @@ fn completeDot(builder: *Builder, loc: offsets.Loc) Analyser.Error!void {
     }
 }
 
+fn completeError(builder: *Builder, loc: offsets.Loc) Analyser.Error!void {
+    const tracy_zone = tracy.trace(@src());
+    defer tracy_zone.end();
+
+    const tree = &builder.orig_handle.tree;
+
+    const err_token_index = offsets.sourceIndexToTokenIndex(tree, loc.start).pickPreferred(&.{.period}, tree) orelse return;
+    if (err_token_index < 2) return;
+    const dot_token_index = err_token_index + 1;
+
+    const nodes = try ast.nodesOverlappingIndexIncludingParseErrors(builder.arena, tree, loc.start);
+    const dot_context = getSwitchOrStructInitContext(tree, dot_token_index, nodes) orelse return;
+    const used_members_set = try collectUsedMembersSet(builder, dot_context.likely, dot_token_index);
+    const containers = try collectContainerNodes(builder, builder.orig_handle, dot_context);
+    for (containers) |container| {
+        try collectErrorSetNames(builder, container, used_members_set);
+    }
+}
+
+fn collectErrorSetNames(
+    builder: *Builder,
+    container: Analyser.Type,
+    omit_members: std.BufSet,
+) Analyser.Error!void {
+    const ip = builder.analyser.ip;
+    const key = switch (container.data) {
+        .ip_index => |info| ip.indexToKey(info.type),
+        else => return,
+    };
+    if (key != .error_set_type) return;
+    const names = key.error_set_type.names;
+    for (0..names.len) |idx| {
+        const str = names.at(@intCast(idx), ip);
+        const name = try std.fmt.allocPrint(builder.arena, "{f}", .{str.fmt(ip.io, &ip.string_pool)});
+        if (omit_members.contains(name)) continue;
+        try builder.completions.append(builder.arena, .{
+            .label = try std.fmt.allocPrint(builder.arena, "error.{s}", .{name}),
+            .filterText = name,
+            .insertText = name,
+            .kind = .Constant,
+        });
+    }
+}
+
 /// Asserts that `pos_context` is one of the following:
 ///  - `.import_string_literal`
 ///  - `.cinclude_string_literal`
@@ -953,6 +997,7 @@ pub fn completionAtIndex(
         .var_access, .empty => try completeGlobal(&builder),
         .field_access => |loc| try completeFieldAccess(&builder, loc),
         .enum_literal => |loc| try completeDot(&builder, loc),
+        .error_access => |loc| try completeError(&builder, loc),
         .label_access, .label_decl => try completeLabel(&builder),
         .import_string_literal,
         .cinclude_string_literal,

tests/lsp_features/completion.zig

@@ -1925,6 +1925,125 @@ test "switch cases" {
     });
 }
 
+test "switch on error set - all values are suggested" {
+    try testCompletion(
+        \\const err: error{E1, E2} = undefined;
+        \\switch(err) {
+        \\    error.<cursor>
+        \\}
+    , &.{
+        .{ .label = "error.E1", .kind = .Constant },
+        .{ .label = "error.E2", .kind = .Constant },
+    });
+}
+
+test "switch on error set - already used values are not suggested" {
+    try testCompletion(
+        \\const err: error{E1, E2} = undefined;
+        \\switch(err) {
+        \\    error.E1 => {},
+        \\    error.<cursor>
+        \\}
+    , &.{
+        .{ .label = "error.E2", .kind = .Constant },
+    });
+}
+
+test "switch on error set - error unions get all values" {
+    try testCompletion(
+        \\const Err2 = error{F1, F2};
+        \\const Err = error{E1, E2} || Err2;
+        \\const err: Err = undefined;
+        \\switch(err) {
+        \\    error.<cursor>
+        \\}
+    , &.{
+        .{ .label = "error.E1", .kind = .Constant },
+        .{ .label = "error.E2", .kind = .Constant },
+        .{ .label = "error.F1", .kind = .Constant },
+        .{ .label = "error.F2", .kind = .Constant },
+    });
+}
+
+test "switch on error set - text edits result" {
+    try testCompletionTextEdit(.{
+        .source =
+        \\const err: error{E1, E2} = undefined;
+        \\switch(err) {
+        \\    error.<cursor>
+        \\}
+        ,
+        .label = "error.E1",
+        .expected_insert_line = "    error.E1",
+        .expected_replace_line = "    error.E1",
+        .enable_snippets = false,
+    });
+}
+test "switch on error set - insert/replace text edits" {
+    try testCompletionTextEdit(.{
+        .source =
+        \\const err: error{Err1, Err2} = undefined;
+        \\switch(err) {
+        \\    error.E<cursor>0
+        \\}
+        ,
+        .label = "error.Err1",
+        .expected_insert_line = "    error.Err10",
+        .expected_replace_line = "    error.Err1",
+        .enable_snippets = false,
+    });
+}
+
+test "switch on error set - completion inside catch block works" {
+    try testCompletion(
+        \\fn idk() error{ E1, E2 }!void {}
+        \\test {
+        \\  idk() catch |err| {
+        \\      switch (err) {
+        \\          error.<cursor>
+        \\      }
+        \\  };
+        \\}
+    , &.{
+        .{ .label = "error.E1", .kind = .Constant },
+        .{ .label = "error.E2", .kind = .Constant },
+    });
+}
+
+test "switch on error set - completion inside catch statement" {
+    if (true) return error.SkipZigTest; // TODO un-skip after https://github.com/zigtools/zls/issues/2341 and/or https://github.com/zigtools/zls/issues/1112
+    try testCompletion(
+        \\fn idk() error{ E1, E2 }!void {}
+        \\test {
+        \\  idk() catch |err| switch (err) {
+        \\      error.<cursor>
+        \\  };
+        \\}
+    , &.{
+        .{ .label = "error.E1", .kind = .Constant },
+        .{ .label = "error.E2", .kind = .Constant },
+    });
+}
+
+test "switch on error set - Works in a function of a container" {
+    if (true) return error.SkipZigTest; // TODO un-skip after https://github.com/zigtools/zls/issues/1535
+    try testCompletion(
+        \\fn idk() error{ E1, E2 }!void {}
+        \\pub const Manager = struct {
+        \\    pub fn testIt() void {
+        \\        _ = idk() catch |err| {
+        \\            switch(err) {
+        \\                error.<cursor>
+        \\            }
+        \\        };
+        \\    }
+        \\};
+    , &.{
+        .{ .label = "error.E1", .kind = .Constant },
+        .{ .label = "error.E2", .kind = .Constant },
+    });
+}
+
 test "error set" {
     try testCompletion(
         \\const E = error {