verilog-lint-concrete-fix-advisor

name: verilog-lint-concrete-fix-advisor description: Use this skill when the user provides Verilog/SystemVerilog code plus a lint warning and wants a specific, code-aware repair recommendation in a concise Chinese JSON report rather than a generic lint-tool message, especially incomplete case coverage warnings such as W69 where the agent must identify missing case items or propose a concrete default branch. license: MIT metadata: author: zk version: "1.1"

Verilog Lint Concrete Fix Advisor

When to Use

• The user provides RTL code and a lint warning.
• The user wants a concrete fix, not a generic message such as "add missing cases or default".
• The user wants the result saved as a compact Chinese JSON report.
• The issue involves incomplete case, missing default, incomplete assignment, unused variable caused by unreachable code, or another warning where source-specific context determines the right fix.
• The warning looks like W69 or says case branches are incomplete.

Core Principle

The final advice must be tied to the exact RTL.

Do not answer with only generic text such as:

Add case clauses or a default clause.

Instead, inspect the code and state the missing condition or the exact branch to add.

For example, if the RTL is:

case(in3)
  2'b00 : out[0] = in1 || mem[0];
  2'b01 : out[1] = in1 && mem[1];
  2'b11 : out[2] = in2 && mem[3];
endcase

具体诊断应写成：

case 选择信号为 2 bit，当前覆盖了 00、01、11，缺少的取值是 2'b10。

The concrete fix should include one or both of:

2'b10 : out[...] = ...;  // fill in intended behavior

or:

default: out[...] = ...; // fill in safe intended behavior

Workflow

1. Locate the exact construct

• Read the warning line and surrounding RTL.
• Identify the affected construct: case, if/else, always, assignment, declaration, or instance.
• Do not diagnose from the lint text alone.

2. For incomplete case warnings, run the helper when useful

Use:

python skills/verilog-lint-concrete-fix-advisor/scripts/analyze_case_coverage.py <source_file>

Optional line-targeted mode:

python skills/verilog-lint-concrete-fix-advisor/scripts/analyze_case_coverage.py <source_file> --line <line_number>

The script emits JSON with:

• selector expression,
• inferred selector width,
• explicit case values,
• missing binary values,
• whether a default branch exists.

Use the script output as evidence, not as a substitute for reading the code.

3. Produce concrete repair options

For an incomplete case:

• If missing values are finite and clear, list each missing item explicitly.
• If the intended behavior is unknown, say so and use placeholders only where semantics are user-defined.
• If a safe default behavior is obvious from surrounding assignments, propose it.
• If no safe default is obvious, propose a default branch but explicitly state that the RHS must be filled with the intended behavior.

For other lint warnings:

• Identify the source-level root cause.
• Explain why the tool reports the symptom.
• Propose a localized RTL edit, not a broad coding guideline.

4. Write a compact Chinese JSON report

• Unless the user explicitly asks for another path, write the report to:

reports/verilog_lint_fix_advisor_<YYYYMMDD_HHMMSS>.json

• Generate the timestamp from the running environment. Do not guess it.
• The final assistant response should be brief and in Chinese: state the JSON report path and the fix item count. Do not duplicate the full report in prose unless the user asks.
• The JSON report must contain only core content:

{
  "summary": {
    "source_files": ["rtl/top.sv"],
    "lint_warning_count": 1,
    "fix_item_count": 1,
    "output_path": "reports/verilog_lint_fix_advisor_20260428_153000.json"
  },
  "fix_items": [
    {
      "id": "FIX_001",
      "file": "rtl/top.sv",
      "line": 42,
      "lint_rule": "W69",
      "construct": "case(sel)",
      "root_cause": "case 选择信号为 2 bit，当前覆盖了 2'b00、2'b01、2'b11，但缺少 2'b10，且没有 default 分支。",
      "evidence": {
        "selector": "sel",
        "inferred_width": 2,
        "explicit_values": ["2'b00", "2'b01", "2'b11"],
        "missing_values": ["2'b10"],
        "has_default": false,
        "code_snippet": "case (sel) ..."
      },
      "fix_options": [
        {
          "type": "add_case_item",
          "patch": "2'b10: out = <设计意图对应的取值>;",
          "requires_designer_confirmation": true
        },
        {
          "type": "add_default",
          "patch": "default: out = <安全默认值或设计意图对应的取值>;",
          "requires_designer_confirmation": true
        }
      ],
      "confirmation_needed": [
        "需要设计者确认 selector 取值为 2'b10 时的预期行为。"
      ]
    }
  ]
}

Field rules:

• summary must contain only source files, warning count, fix item count, and output path.
• fix_items must contain one entry per analyzed warning or grouped warning.
• root_cause must be source-specific, concise, and written in Chinese.
• evidence must contain only facts read from the RTL or helper output.
• fix_options must contain concrete local edits only.
• patch and confirmation_needed must be written in Chinese except for code, signal names, literals, and file paths.
• confirmation_needed must be empty when the correct behavior is fully determined from code context.
• Do not add broad background, coding style essays, or generic lint explanations.
• Do not include a field named why_not_generic or 为什么不是泛泛建议; this is redundant once evidence and concrete fixes are present.

Guardrails

• Do not invent intended logic for missing branches.
• Do not silently add default if an explicit missing enumerated value is better for readability or coverage.
• Do not treat default as always correct; in safety-critical decode logic, explicit enumeration can be preferable.
• Do not modify unrelated branches.
• Preserve source signal names and widths.