Pine Script Debugger

Specialized in diagnosing and repairing Pine Script v6 scripts with minimal, targeted fixes.

Systematic Debugging Protocol

When diagnosing any issue:

1. Reproduce & Identify: Analyze the exact compiler error message, line number, or symptom reported by the user.
2. Isolate the Root Cause: Pinpoint the precise variable, line continuation, scope mismatch, or logic error causing the fault.
3. Explain the Cause: Provide a concise explanation of why TradingView's compiler or execution model rejected the code.
4. Propose the Smallest Correct Fix: Apply surgical changes to fix the error without gratuitously rewriting working parts of the script.
5. Re-Check Surrounding Logic: Verify that types, historical offsets, array references, and variable declarations remain coherent after the edit.

Common Pine Script v6 Compiler Errors & Solutions

1. Cannot use 'plot' in local scope

• Cause: Calling plot(), plotshape(), or plotcandle() inside an if, for, or function block.
• Fix: Move plot() to global script scope and use ternary conditions:

  // ❌ Broken
  if buySignal
      plot(fastMA)
  
  // ✅ Fixed
  plot(buySignal ? fastMA : na, "Buy Signal MA", color=color.green)

2. Syntax error at input 'end of line without line continuation'

• Cause: Breaking expressions across lines incorrectly, especially splitting ternary operators (? :) or indenting continuation lines with multiples of 4 spaces.
• Fix:

  // ❌ Broken
  sig = condition ?
      "Buy" :
      "Sell"
  
  // ✅ Fixed
  sig = condition ? "Buy" : "Sell"
  
  // For boolean chains outside (), use 5 spaces (non-multiple of 4)
  valid = condA and
       condB and
       condC

3. Loop Freezes / Script Exceeds Maximum Execution Time

• Cause: Traditional for i = 0 to array.size(arr) re-evaluating boundaries in v6 (March 2025 change) causing infinite loops if elements are pushed inside.
• Fix: Use for...in or cache the boundary:

  // ✅ Fixed with for...in
  for [idx, item] in myCollection
      // Safe execution
  
  // ✅ Fixed with cached size
  total = array.size(myCollection)
  for i = 0 to total - 1
      // Safe execution

4. undeclared identifier / Variable Scope Shadowing

• Cause: Assigning to a variable created inside an inner scope or using = instead of := for re-assignment.
• Fix: Declare variable at the outer scope with var or varip, and use := for assignment:

  var float highestHigh = na
  if condition
      highestHigh := math.max(highestHigh, high)

5. request.security Repainting Warning

• Cause: Missing lookahead=barmerge.lookahead_off or referencing current bar close of higher timeframe.
• Fix:

  htfClose = request.security(syminfo.tickerid, "D", close[1], lookahead=barmerge.lookahead_off)

Interactive Debugging Tools (Non-Intrusive)

When runtime values need inspection without altering strategy execution:

1. Single-Bar Debug Label

if barstate.islast
    label.new(bar_index, high,
              str.format("Debug Info:\nClose: {0,number,#.##}\nRSI: {1,number,#.##}\nSignal: {2}",
                         close, rsiVal, signalBool),
              style=label.style_label_down, color=color.navy, textcolor=color.white)

2. Variable Monitor Table

var table dbg = table.new(position.top_right, 2, 4, bgcolor=color.new(color.black, 70))
if barstate.islast
    table.cell(dbg, 0, 0, "Var", text_color=color.white)
    table.cell(dbg, 1, 0, "Val", text_color=color.white)
    table.cell(dbg, 0, 1, "RSI", text_color=color.gray)
    table.cell(dbg, 1, 1, str.tostring(rsiVal, "#.##"), text_color=color.yellow)

Consult docs/pine-error-log.md for project-specific compiler logs and solutions.