implement global error set completion

src/analysis.zig

@@ -405,6 +405,16 @@ pub fn resolveTypeOfNode(analysis_ctx: *AnalysisContext, node: *ast.Node) ?*ast.
                 else => decl,
             };
         },
+        .ErrorSetDecl => {
+            const set = node.cast(ast.Node.ErrorSetDecl).?;
+            var i: usize = 0;
+            while (set.iterate(i)) |decl| : (i+=1)  {
+                const tag = decl.cast(ast.Node.ErrorTag).?;
+                // TODO handle errors better?
+                analysis_ctx.error_completions.add(analysis_ctx.tree(), tag) catch {};
+            }
+            return node;
+        },
         .SuffixOp => {
             const suffix_op = node.cast(ast.Node.SuffixOp).?;
             switch (suffix_op.op) {
@@ -499,7 +509,7 @@ pub fn resolveTypeOfNode(analysis_ctx: *AnalysisContext, node: *ast.Node) ?*ast.
             analysis_ctx.onContainer(node.cast(ast.Node.ContainerDecl).?) catch return null;
             return node;
         },
-        .MultilineStringLiteral, .StringLiteral, .ErrorSetDecl, .FnProto => return node,
+        .MultilineStringLiteral, .StringLiteral, .FnProto => return node,
         else => std.debug.warn("Type resolution case not implemented; {}\n", .{node.id}),
     }
     return null;
@@ -916,6 +926,7 @@ pub const PositionContext = union(enum) {
     string_literal: SourceRange,
     field_access: SourceRange,
     var_access: SourceRange,
+    global_error_set,
     enum_literal,
     other,
     empty,
@@ -930,6 +941,7 @@ pub const PositionContext = union(enum) {
             .enum_literal => null,
             .other => null,
             .empty => null,
+            .global_error_set => null,
         };
     }
 };
@@ -1002,6 +1014,7 @@ pub fn documentPositionContext(allocator: *std.mem.Allocator, document: types.Te
                 .enum_literal => curr_ctx.ctx = .empty,
                 .field_access => {},
                 .other => {},
+                .global_error_set => {},
                 else => curr_ctx.ctx = .{
                     .field_access = tokenRangeAppend(curr_ctx.ctx.range().?, tok),
                 },
@@ -1024,6 +1037,7 @@ pub fn documentPositionContext(allocator: *std.mem.Allocator, document: types.Te
                     (try peek(&stack)).ctx = .empty;
                 }
             },
+            .Keyword_error => curr_ctx.ctx = .global_error_set,
             else => curr_ctx.ctx = .empty,
         }
 

src/document_store.zig

@@ -30,12 +30,56 @@ pub const Handle = struct {
     }
 };
 
+pub const ErrorCompletion = struct {
+    values: std.StringHashMap(void),
+    completions: std.ArrayList(types.CompletionItem),
+
+    pub fn init(allocator: *std.mem.Allocator) ErrorCompletion {
+        return .{
+            .values = std.StringHashMap(void).init(allocator),
+            .completions = std.ArrayList(types.CompletionItem).init(allocator),
+        };
+    }
+
+    pub fn deinit(self: *ErrorCompletion) void {
+        const alloc = self.values.allocator;
+        for (self.completions.items) |item| {
+            alloc.free(item.label);
+            if (item.documentation) |some| alloc.free(some.value);
+        }
+        self.values.deinit();
+        self.completions.deinit();
+    }
+
+    pub fn add(self: *ErrorCompletion, tree: *std.zig.ast.Tree, tag: *std.zig.ast.Node.ErrorTag) !void {
+        const name = tree.tokenSlice(tag.name_token);
+        if (self.values.contains(name)) return;
+        const alloc = self.values.allocator;
+        const item = types.CompletionItem{
+            .label = try std.mem.dupe(alloc, u8, name),
+            .kind = .Constant,
+            .documentation = if (try analysis.getDocComments(alloc, tree, &tag.base)) |docs|
+                .{
+                    .kind = .Markdown,
+                    .value = docs,
+                }
+            else
+                null,
+        };
+
+        try self.values.putNoClobber(item.label, {});
+        try self.completions.append(item);
+    }
+};
+
 allocator: *std.mem.Allocator,
 handles: std.StringHashMap(*Handle),
 has_zig: bool,
 build_files: std.ArrayListUnmanaged(*BuildFile),
 build_runner_path: []const u8,
 
+error_completions: ErrorCompletion,
+
 pub fn init(
     self: *DocumentStore,
     allocator: *std.mem.Allocator,
@@ -47,6 +91,7 @@ pub fn init(
     self.has_zig = has_zig;
     self.build_files = .{};
     self.build_runner_path = build_runner_path;
+    self.error_completions = ErrorCompletion.init(allocator);
 }
 
 const LoadPackagesContext = struct {
@@ -478,6 +523,7 @@ pub const AnalysisContext = struct {
     scope_nodes: []*std.zig.ast.Node,
     in_container: *std.zig.ast.Node,
     std_uri: ?[]const u8,
+    error_completions: *ErrorCompletion,
 
     pub fn tree(self: AnalysisContext) *std.zig.ast.Tree {
         return self.handle.tree;
@@ -584,6 +630,7 @@ pub const AnalysisContext = struct {
             .scope_nodes = try std.mem.dupe(&self.arena.allocator, *std.zig.ast.Node, self.scope_nodes),
             .in_container = self.in_container,
             .std_uri = self.std_uri,
+            .error_completions = self.error_completions,
         };
     }
 };
@@ -623,6 +670,7 @@ pub fn analysisContext(
         .scope_nodes = scope_nodes.items,
         .in_container = in_container,
         .std_uri = std_uri,
+        .error_completions = &self.error_completions,
     };
 }
 
@@ -652,4 +700,5 @@ pub fn deinit(self: *DocumentStore) void {
     }
 
     self.build_files.deinit(self.allocator);
+    self.error_completions.deinit();
 }

src/main.zig

@@ -760,6 +760,15 @@ fn processJsonRpc(parser: *std.json.Parser, json: []const u8, config: Config) !v
                 }),
                 .var_access, .empty => try completeGlobal(id, pos_index, handle, this_config),
                 .field_access => |range| try completeFieldAccess(id, handle, pos, range, this_config),
+                .global_error_set =>  try send(types.Response{
+                    .id = .{ .Integer = id },
+                    .result = .{
+                        .CompletionList = .{
+                            .isIncomplete = false,
+                            .items = document_store.error_completions.completions.items,
+                        },
+                    },
+                }),
                 else => try respondGeneric(id, no_completions_response),
             }
         } else {