Allow attaching (remote and local) with no program

src/GDBDebugSession.ts

@@ -338,15 +338,19 @@ export class GDBDebugSession extends LoggingDebugSession {
         );
 
         await this.spawn(args);
-        if (!args.program) {
-            this.sendErrorResponse(
-                response,
-                1,
-                'The program must be specified in the request arguments'
-            );
-            return;
+        if (request == 'launch') {
+            if (!args.program) {
+                this.sendErrorResponse(
+                    response,
+                    1,
+                    'The program must be specified in the request arguments'
+                );
+                return;
+            }
+        }
+        if (args.program) {
+            await this.gdb.sendFileExecAndSymbols(args.program);
         }
-        await this.gdb.sendFileExecAndSymbols(args.program);
         await this.gdb.sendEnablePrettyPrint();
 
         if (request === 'attach') {
@@ -997,7 +1001,7 @@ export class GDBDebugSession extends LoggingDebugSession {
             }
             response.body = {
                 allThreadsContinued: isAllThreadsContinued,
-            }
+            };
             this.sendResponse(response);
         } catch (err) {
             this.sendErrorResponse(

src/GDBTargetDebugSession.ts

@@ -275,7 +275,9 @@ export class GDBTargetDebugSession extends GDBDebugSession {
         try {
             this.isAttach = true;
             await this.spawn(args);
-            await this.gdb.sendFileExecAndSymbols(args.program);
+            if (args.program) {
+                await this.gdb.sendFileExecAndSymbols(args.program);
+            }
             await this.gdb.sendEnablePrettyPrint();
             if (args.imageAndSymbols) {
                 if (args.imageAndSymbols.symbolFileName) {

src/integration-tests/attach.spec.ts

@@ -51,4 +51,17 @@ describe('attach', function () {
         await dc.attachHitBreakpoint(attachArgs, { line: 25, path: src });
         expect(await dc.evaluate('argv[1]')).to.contain('running-from-spawn');
     });
+
+    it('can attach and hit a breakpoint with no program specified', async function () {
+        if (isRemoteTest) {
+            // attachRemote.spec.ts is the test for when isRemoteTest
+            this.skip();
+        }
+
+        const attachArgs = fillDefaults(this.test, {
+            processId: `${inferior.pid}`,
+        } as AttachRequestArguments);
+        await dc.attachHitBreakpoint(attachArgs, { line: 25, path: src });
+        expect(await dc.evaluate('argv[1]')).to.contain('running-from-spawn');
+    });
 });

src/integration-tests/attachRemote.spec.ts

@@ -10,6 +10,7 @@
 
 import * as cp from 'child_process';
 import * as path from 'path';
+import * as os from 'os';
 import {
     TargetAttachRequestArguments,
     TargetAttachArguments,
@@ -74,4 +75,19 @@ describe('attach remote', function () {
         await dc.attachHitBreakpoint(attachArgs, { line: 3, path: emptySrc });
         expect(await dc.evaluate('argv[1]')).to.contain('running-from-spawn');
     });
+
+    it('can attach remote and hit a breakpoint without a program', async function () {
+        if (os.platform() === 'win32') {
+            // win32 host does support this use case
+            this.skip();
+        }
+        const attachArgs = fillDefaults(this.test, {
+            target: {
+                type: 'remote',
+                parameters: [`localhost:${port}`],
+            } as TargetAttachArguments,
+        } as TargetAttachRequestArguments);
+        await dc.attachHitBreakpoint(attachArgs, { line: 3, path: emptySrc });
+        expect(await dc.evaluate('argv[1]')).to.contain('running-from-spawn');
+    });
 });