If you are getting this in GDB on macOS while trying to run a program:

Unable to find Mach task port for process-id 57573: (os/kern) failure (0x5).
 (please check gdb is codesigned - see taskgated(8))

1. Open Keychain Access
2. In menu, open Keychain Access > Certificate Assistant > Create a certificate
3. Give it a name (e.g. gdbc)

• Identity type: Self Signed Root
• Certificate type: Code Signing
• Check: let me override defaults

4. Continue until "specify a location for..."
5. Set Keychain location to System
6. Create certificate and close Certificate Assistant.
7. Find certificate in System keychain.
8. Double click certificate
9. Expand Trust, set Code signing to always trust
10. Restart taskgated in terminal: sudo killall taskgated
11. Create entitlements file: Copy the text below and save it in gdb.xml in your current directory.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
"http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>com.apple.security.cs.allow-jit</key>
    <true/>
    <key>com.apple.security.cs.allow-unsigned-executable-memory</key>
    <true/>
    <key>com.apple.security.cs.allow-dyld-environment-variables</key>
    <true/>
    <key>com.apple.security.cs.disable-library-validation</key>
    <true/>
    <key>com.apple.security.cs.disable-executable-page-protection</key>
    <true/>
    <key>com.apple.security.cs.debugger</key>
    <true/>
    <key>com.apple.security.get-task-allow</key>
    <true/>
</dict>
</plist>

12. Codesign GDB using your certificate: codesign --entitlements gdb.xml -fs gdbc <loc of gdb>
    Replace <loc of gdb> with location of GDB on your machine.
13. GDB should now work as expected.