1# Debugger
  2
  3Zed uses the [Debug Adapter Protocol (DAP)](https://microsoft.github.io/debug-adapter-protocol/) to provide debugging functionality across multiple programming languages.
  4DAP is a standardized protocol that defines how debuggers, editors, and IDEs communicate with each other.
  5It allows Zed to support various debuggers without needing to implement language-specific debugging logic.
  6Zed implements the client side of the protocol, and various _debug adapters_ implement the server side.
  7
  8This protocol enables features like setting breakpoints, stepping through code, inspecting variables,
  9and more, in a consistent manner across different programming languages and runtime environments.
 10
 11## Supported Languages
 12
 13To debug code written in a specific language, Zed needs to find a debug adapter for that language. Some debug adapters are provided by Zed without additional setup, and some are provided by [language extensions](./extensions/debugger-extensions.md). The following languages currently have debug adapters available:
 14
 15<!-- keep this sorted -->
 16
 17- [C](./languages/c.md#debugging) (built-in)
 18- [C++](./languages/cpp.md#debugging) (built-in)
 19- [Go](./languages/go.md#debugging) (built-in)
 20- [JavaScript](./languages/javascript.md#debugging) (built-in)
 21- [PHP](./languages/php.md#debugging) (built-in)
 22- [Python](./languages/python.md#debugging) (built-in)
 23- [Ruby](./languages/ruby.md#debugging) (provided by extension)
 24- [Rust](./languages/rust.md#debugging) (built-in)
 25- [Swift](./languages/swift.md#debugging) (provided by extension)
 26- [TypeScript](./languages/typescript.md#debugging) (built-in)
 27
 28> If your language isn't listed, you can contribute by adding a debug adapter for it. Check out our [debugger extensions](./extensions/debugger-extensions.md) documentation for more information.
 29
 30Follow those links for language- and adapter-specific information and examples, or read on for more about Zed's general debugging features that apply to all adapters.
 31
 32## Getting Started
 33
 34For most languages, the fastest way to get started is to run {#action debugger::Start} ({#kb debugger::Start}). This opens the _new process modal_, which shows you a contextual list of preconfigured debug tasks for the current project. Debug tasks are created from tests, entry points (like a `main` function), and from other sources — consult the documentation for your language for full information about what's supported.
 35
 36You can open the same modal by clicking the "plus" button at the top right of the debug panel.
 37
 38For languages that don't provide preconfigured debug tasks (this includes C, C++, and some extension-supported languages), you can define debug configurations in the `.zed/debug.json` file in your project root. This file should be an array of configuration objects:
 39
 40```json [debug]
 41[
 42  {
 43    "adapter": "CodeLLDB",
 44    "label": "First configuration"
 45    // ...
 46  },
 47  {
 48    "adapter": "Debugpy",
 49    "label": "Second configuration"
 50    // ...
 51  }
 52]
 53```
 54
 55Check the documentation for your language for example configurations covering typical use-cases. Once you've added configurations to `.zed/debug.json`, they'll appear in the list in the new process modal.
 56
 57Zed will also load debug configurations from `.vscode/launch.json`, and show them in the new process modal if no configurations are found in `.zed/debug.json`.
 58
 59### Launching & Attaching
 60
 61Zed debugger offers two ways to debug your program; you can either _launch_ a new instance of your program or _attach_ to an existing process.
 62Which one you choose depends on what you are trying to achieve.
 63
 64When launching a new instance, Zed (and the underlying debug adapter) can often do a better job at picking up the debug information compared to attaching to an existing process, since it controls the lifetime of a whole program.
 65Running unit tests or a debug build of your application is a good use case for launching.
 66
 67Compared to launching, attaching to an existing process might seem inferior, but that's far from truth; there are cases where you cannot afford to restart your program, because for example, the bug is not reproducible outside of a production environment or some other circumstances.
 68
 69## Configuration
 70
 71Zed requires the `adapter` and `label` fields for all debug tasks. In addition, Zed will use the `build` field to run any necessary setup steps before the debugger starts [(see below)](#build-tasks), and can accept a `tcp_connection` field to connect to an existing process.
 72
 73All other fields are provided by the debug adapter and can contain [task variables](./tasks.md#variables). Most adapters support `request`, `program`, and `cwd`:
 74
 75```json [debug]
 76[
 77  {
 78    // The label for the debug configuration and used to identify the debug session inside the debug panel & new process modal
 79    "label": "Example Start debugger config",
 80    // The debug adapter that Zed should use to debug the program
 81    "adapter": "Example adapter name",
 82    // Request:
 83    //  - launch: Zed will launch the program if specified, or show a debug terminal with the right configuration
 84    //  - attach: Zed will attach to a running program to debug it, or when the process_id is not specified, will show a process picker (only supported for node currently)
 85    "request": "launch",
 86    // The program to debug. This field supports path resolution with ~ or . symbols.
 87    "program": "path_to_program",
 88    // cwd: defaults to the current working directory of your project ($ZED_WORKTREE_ROOT)
 89    "cwd": "$ZED_WORKTREE_ROOT"
 90  }
 91]
 92```
 93
 94Check your debug adapter's documentation for more information on the fields it supports.
 95
 96### Build tasks
 97
 98Zed allows embedding a Zed task in the `build` field that is run before the debugger starts. This is useful for setting up the environment or running any necessary setup steps before the debugger starts.
 99
100```json [debug]
101[
102  {
103    "label": "Build Binary",
104    "adapter": "CodeLLDB",
105    "program": "path_to_program",
106    "request": "launch",
107    "build": {
108      "command": "make",
109      "args": ["build", "-j8"]
110    }
111  }
112]
113```
114
115Build tasks can also refer to the existing tasks by unsubstituted label:
116
117```json [debug]
118[
119  {
120    "label": "Build Binary",
121    "adapter": "CodeLLDB",
122    "program": "path_to_program",
123    "request": "launch",
124    "build": "my build task" // Or "my build task for $ZED_FILE"
125  }
126]
127```
128
129### Automatic scenario creation
130
131Given a Zed task, Zed can automatically create a scenario for you. Automatic scenario creation also powers our scenario creation from gutter.
132Automatic scenario creation is currently supported for Rust, Go, Python, JavaScript, and TypeScript.
133
134## Breakpoints
135
136To set a breakpoint, simply click next to the line number in the editor gutter.
137Breakpoints can be tweaked depending on your needs; to access additional options of a given breakpoint, right-click on the breakpoint icon in the gutter and select the desired option.
138At present, you can:
139
140- Add a log to a breakpoint, which will output a log message whenever that breakpoint is hit.
141- Make the breakpoint conditional, which will only stop at the breakpoint when the condition is met. The syntax for conditions is adapter-specific.
142- Add a hit count to a breakpoint, which will only stop at the breakpoint after it's hit a certain number of times.
143- Disable a breakpoint, which will prevent it from being hit while leaving it visible in the gutter.
144
145Some debug adapters (e.g. CodeLLDB and JavaScript) will also _verify_ whether your breakpoints can be hit; breakpoints that cannot be hit are surfaced more prominently in the UI.
146
147All breakpoints enabled for a given project are also listed in "Breakpoints" item in your debugging session UI. From "Breakpoints" item in your UI you can also manage exception breakpoints.
148The debug adapter will then stop whenever an exception of a given kind occurs. Which exception types are supported depends on the debug adapter.
149
150## Settings
151
152The settings for the debugger are grouped under the `debugger` key in `settings.json`:
153
154- `dock`: Determines the position of the debug panel in the UI.
155- `stepping_granularity`: Determines the stepping granularity.
156- `save_breakpoints`: Whether the breakpoints should be reused across Zed sessions.
157- `button`: Whether to show the debug button in the status bar.
158- `timeout`: Time in milliseconds until timeout error when connecting to a TCP debug adapter.
159- `log_dap_communications`: Whether to log messages between active debug adapters and Zed.
160- `format_dap_log_messages`: Whether to format DAP messages when adding them to the debug adapter logger.
161
162### Dock
163
164- Description: The position of the debug panel in the UI.
165- Default: `bottom`
166- Setting: debugger.dock
167
168**Options**
169
1701. `left` - The debug panel will be docked to the left side of the UI.
1712. `right` - The debug panel will be docked to the right side of the UI.
1723. `bottom` - The debug panel will be docked to the bottom of the UI.
173
174```json [settings]
175"debugger": {
176  "dock": "bottom"
177},
178```
179
180### Stepping granularity
181
182- Description: The Step granularity that the debugger will use
183- Default: `line`
184- Setting: `debugger.stepping_granularity`
185
186**Options**
187
1881. Statement - The step should allow the program to run until the current statement has finished executing.
189   The meaning of a statement is determined by the adapter and it may be considered equivalent to a line.
190   For example 'for(int i = 0; i < 10; i++)' could be considered to have 3 statements 'int i = 0', 'i < 10', and 'i++'.
191
192```json [settings]
193{
194  "debugger": {
195    "stepping_granularity": "statement"
196  }
197}
198```
199
2002. Line - The step should allow the program to run until the current source line has executed.
201
202```json [settings]
203{
204  "debugger": {
205    "stepping_granularity": "line"
206  }
207}
208```
209
2103. Instruction - The step should allow one instruction to execute (e.g. one x86 instruction).
211
212```json [settings]
213{
214  "debugger": {
215    "stepping_granularity": "instruction"
216  }
217}
218```
219
220### Save Breakpoints
221
222- Description: Whether the breakpoints should be saved across Zed sessions.
223- Default: `true`
224- Setting: `debugger.save_breakpoints`
225
226**Options**
227
228`boolean` values
229
230```json [settings]
231{
232  "debugger": {
233    "save_breakpoints": true
234  }
235}
236```
237
238### Button
239
240- Description: Whether the button should be displayed in the debugger toolbar.
241- Default: `true`
242- Setting: `debugger.show_button`
243
244**Options**
245
246`boolean` values
247
248```json [settings]
249{
250  "debugger": {
251    "show_button": true
252  }
253}
254```
255
256### Timeout
257
258- Description: Time in milliseconds until timeout error when connecting to a TCP debug adapter.
259- Default: `2000`
260- Setting: `debugger.timeout`
261
262**Options**
263
264`integer` values
265
266```json [settings]
267{
268  "debugger": {
269    "timeout": 3000
270  }
271}
272```
273
274### Inline Values
275
276- Description: Whether to enable editor inlay hints showing the values of variables in your code during debugging sessions.
277- Default: `true`
278- Setting: `inlay_hints.show_value_hints`
279
280**Options**
281
282```json [settings]
283{
284  "inlay_hints": {
285    "show_value_hints": false
286  }
287}
288```
289
290Inline value hints can also be toggled from the Editor Controls menu in the editor toolbar.
291
292### Log Dap Communications
293
294- Description: Whether to log messages between active debug adapters and Zed. (Used for DAP development)
295- Default: false
296- Setting: debugger.log_dap_communications
297
298**Options**
299
300`boolean` values
301
302```json [settings]
303{
304  "debugger": {
305    "log_dap_communications": true
306  }
307}
308```
309
310### Format Dap Log Messages
311
312- Description: Whether to format DAP messages when adding them to the debug adapter logger. (Used for DAP development)
313- Default: false
314- Setting: debugger.format_dap_log_messages
315
316**Options**
317
318`boolean` values
319
320```json [settings]
321{
322  "debugger": {
323    "format_dap_log_messages": true
324  }
325}
326```
327
328### Customizing Debug Adapters
329
330- Description: Custom program path and arguments to override how Zed launches a specific debug adapter.
331- Default: Adapter-specific
332- Setting: `dap.$ADAPTER.binary` and `dap.$ADAPTER.args`
333
334You can pass `binary`, `args`, or both. `binary` should be a path to a _debug adapter_ (like `lldb-dap`) not a _debugger_ (like `lldb` itself). The `args` setting overrides any arguments that Zed would otherwise pass to the adapter.
335
336```json [settings]
337{
338  "dap": {
339    "CodeLLDB": {
340      "binary": "/Users/name/bin/lldb-dap",
341      "args": ["--wait-for-debugger"]
342    }
343  }
344}
345```
346
347## Theme
348
349The Debugger supports the following theme options:
350
351- `debugger.accent`: Color used to accent breakpoint & breakpoint-related symbols
352- `editor.debugger_active_line.background`: Background color of active debug line
353
354## Troubleshooting
355
356If you're running into problems with the debugger, please [open a GitHub issue](https://github.com/zed-industries/zed/issues/new?template=04_bug_debugger.yml), providing as much context as possible. There are also some features you can use to gather more information about the problem:
357
358- When you have a session running in the debug panel, you can run the {#action dev::CopyDebugAdapterArguments} action to copy a JSON blob to the clipboard that describes how Zed initialized the session. This is especially useful when the session failed to start, and is great context to add if you open a GitHub issue.
359- You can also use the {#action dev::OpenDebugAdapterLogs} action to see a trace of all of Zed's communications with debug adapters during the most recent debug sessions.