time: add time tests and add std symbol coverage checks

[cpunion]

This PR contains two commits:

1) time: add time tests and fix timer semantics

• Adds/updates the test/std/time suite.
• Updates runtime/internal/lib/time so timers/tickers match Go semantics (e.g. Timer.Reset return value behavior).
• Adds missing runtime helper runtime.AssertDivideByZero needed by the updated code.

2) chore: add check_std_symbols std coverage checks

• Adds chore/check_std_symbols (with tests) to enforce std exported-symbol coverage.
• Adds doc/_readme/scripts/check_std_cover.sh.
• Wires the check into CI via:
  • .github/workflows/stdlib-coverage.yml
  • an extra step in .github/workflows/go.yml

Testing strategy

The test/std/time suite is exercised in two ways:

• go test ./test/std/time validates the test harness and expected behavior against the Go toolchain.
• ./llgo.sh test ./test/std/time validates LLGo’s runtime/stdlib implementation matches those expectations.

Verification

• go test ./test/std/time
• ./llgo.sh test ./test/std/time
• go test ./chore/check_std_symbols
• bash doc/_readme/scripts/check_std_cover.sh

[gemini-code-assist]

Summary of Changes

Hello @cpunion, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly updates the time package by synchronizing its test suite and runtime implementation with the standard library, thereby improving its robustness and feature set. It also introduces a new static analysis tool to ensure comprehensive test coverage for exported symbols, reinforcing code quality and maintainability. These changes collectively bring the time package closer to full stdlib compatibility and enhance its utility.

Highlights

• Standard Library time Package Sync: The time test suite and LLGo time runtime shim have been synchronized with the upstream std-test branch, ensuring greater compatibility and up-to-date functionality.
• New Symbol Coverage Checker: A new tool, chore/check_std_symbols, has been introduced to verify that all exported standard library symbols are covered by tests. This tool is integrated into the CI pipeline.
• Runtime Symbol Fix: The missing runtime.AssertDivideByZero symbol, required by the synchronized code, has been added to the runtime.
• Expanded time.Time Functionality: Several new methods have been added to the time.Time type, including Unix(), UnixMilli(), UnixMicro(), In(), Location(), Zone(), ZoneBounds(), AddDate(), Truncate(), and various serialization methods (Binary, Gob, JSON, Text).
• Enhanced Time Zone Handling: The time package now includes LoadLocation() for loading time zone information by name and improved internal Location.lookup mechanisms.

Ignored Files

• Ignored by pattern: .github/workflows/** (2)
  • .github/workflows/go.yml
  • .github/workflows/stdlib-coverage.yml

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[xgopilot]

Code Review Summary

This PR adds a well-structured stdlib symbol coverage checker and syncs the time runtime implementation. The code demonstrates good engineering practices overall. Below are the key findings from comprehensive review:

Highlights:

• Clean separation of concerns between symbol collection and usage tracking
• Proper path traversal protection with pathWithin/pathWithinAbs
• Secure shell script with proper quoting and error handling
• Good use of Go's packages API for AST analysis

Key Issues to Address:

• Missing package-level documentation for the new tool
• Performance: serial package loading should be batched
• Security: strengthen package path validation to reject .. sequences
• Add comprehensive test coverage beyond the basic tests

See inline comments for specific recommendations.

[gemini-code-assist]

Code Review

This pull request synchronizes the time package implementation and its test suite with the standard library, which includes several bug fixes and new features like support for periodic timers and additional time formatting/parsing capabilities. It also introduces a new tool, check_std_symbols, to verify test coverage of exported symbols in standard library packages.

My main feedback is regarding the implementation of the new coverage checker tool. It currently parses the output of go doc to find exported symbols, which is a fragile approach. I've suggested a more robust implementation using the go/packages library.

The rest of the changes, primarily syncing the time package, look solid and bring important improvements.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.58%. Comparing base (5627fb3) to head (9771b45).
⚠️ Report is 26 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1466   +/-   ##
=======================================
  Coverage   90.58%   90.58%           
=======================================
  Files          43       43           
  Lines       11429    11429           
=======================================
  Hits        10353    10353           
  Misses        914      914           
  Partials      162      162           

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