E07943: 'sanitized' cannot be used on variable declarations - sanitize at the function/method entry point

What went wrong

The 'sanitized' keyword CANNOT be used on variable declarations or assignments. Sanitization belongs at function/method entry points, not at assignment sites.

Worked examples

Compilable examples demonstrating this error and the correct fix:

• ek9 -q 950 (Where can the 'sanitized' keyword NOT be used in EK9?)

Rationale

"Rejection at the Source" Philosophy: By the time you're assigning to a variable, the data is already inside the trust boundary. Either:

1. The data came from a sanitized parameter (already safe)
2. The data was computed internally (already trusted)
3. The data came from an external source via a function that should have sanitized its parameters

Sanitizing at assignment creates the wrong mental model:

• It suggests sanitization is the caller's responsibility
• It fragments security logic across the codebase
• It's easy to forget one assignment site

Trace data back to where it entered the system. That entry point (function/method parameter) is where 'sanitized' belongs.

How to fix it

1. REMOVE: 'sanitized' from the variable declaration
2. TRACE: Where did this data originally enter the system?
3. ADD: 'sanitized' to that original function/method parameter
4. All downstream code automatically receives sanitized data

The [EXAMPLE] section below shows 'sanitized' on each kind of declaration ('<-', ':=', '=', ':~:'), and the parameters made 'sanitized' at the entry points instead.

See also

• E07910: sanitized on wrong type (must be String)
• E07920: sanitized in wrong location (must be incoming parameter)
• E07941: sanitized on capture
• E07942: sanitized at call site
• E07943: sanitized on variable declaration (this error)

https://ek9.io/sanitized.html https://ek9.io/forAI.json#$.sanitizedTypes

Examples

Every example is compiled by the EK9 compiler: the first fails exactly as captioned, the others fix it.

Fails with E07943: 'sanitized' cannot be used on variable declarations - sanitize at the function/method entry point

#!ek9
defines module error.e07943.bad

  defines function

    //Helper function returning a string
    getValue()
      <- output as String: "test"

    //ERROR: sanitized on arrow declaration
    badArrowDeclaration()
      -> userInput as String
      //ERROR: Cannot sanitize at variable declaration
      name <- sanitized getValue()
      stdout <- Stdout()
      stdout.println(name)

    //ERROR: sanitized on typed declaration with := operator
    badTypedDeclarationAssign()
      -> userInput as String
      //ERROR: Cannot sanitize on typed variable declaration
      data as sanitized String := userInput
      stdout <- Stdout()
      stdout.println(data)

    //ERROR: sanitized on typed declaration with = operator
    badTypedDeclarationAssign2()
      -> userInput as String
      //ERROR: Cannot sanitize on typed variable declaration
      data as sanitized String = userInput
      stdout <- Stdout()
      stdout.println(data)

    //ERROR: sanitized on typed declaration with :~: operator (merge)
    badTypedDeclarationMerge()
      -> userInput as String
      //ERROR: Cannot sanitize with merge operator
      data as sanitized String :~: userInput
      stdout <- Stdout()
      stdout.println(data)

    //CORRECT: Sanitize at entry point, not at variable declaration
    correctSanitizedParameter()
      -> userInput as sanitized String
      //Assignment receives already-sanitized data
      name <- String(userInput)
      data as String := userInput
      stdout <- Stdout()
      stdout.println(name + data)

Fixed: Sanitize at the entry points

#!ek9
defines module error.e07943.good

  defines function

    //Sanitize the source function's parameter...
    getValue()
      -> input as sanitized String
      <- output as String: input

    //...or this function's entry point
    process()
      -> userInput as sanitized String
      <- rtn as String: getValue(userInput) + String(userInput)