feat(cmake): Enable (-Wall -Werror -Wextra) compilation flag to detect potential bugs early

[SYaoJun]

Reason for this PR

1. Add compilation flags -Wall -Werror -Wextra

The three compilation flags (-Wall, -Werror, -Wextra) are commonly used together in C++ projects. Combined, these flags effectively catch common bugs in C++ code and serve as a robust tool to ensure the code quality of graphar.

I have addressed most of the relevant warnings in the following PRs:

Resolved unused-variables warnings: #840
Fixed compilation warnings: #849

What changes are included in this PR?

At this stage, I can only fix a subset of the remaining warnings and add the three flags (-Wall -Werror -Wextra).

2. Compile third-party dependencies into a separate library to exclude them from these three flags
3. Fix the remaining warnings

• missing copy assignment operators
• unused parameters

Are these changes tested?

yes

Are there any user-facing changes?

no

[codecov-commenter]

Codecov Report

❌ Patch coverage is 3.22581% with 30 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.98%. Comparing base (89c167a) to head (7e0ef9d).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
cpp/src/graphar/arrow/chunk_reader.cc	0.00%	30 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #863      +/-   ##
============================================
- Coverage     80.21%   79.98%   -0.24%     
  Complexity      615      615              
============================================
  Files            93       93              
  Lines         10255    10285      +30     
  Branches       1049     1051       +2     
============================================
  Hits           8226     8226              
- Misses         1789     1819      +30     
  Partials        240      240              

Flag	Coverage Δ
cpp	71.10% <3.22%> (-0.42%)	⬇️

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[SYaoJun]

fix:#848

[Copilot]

Pull request overview

Enables stricter C++ compilation warnings (-Wall -Wextra -Werror) and restructures the CMake build so third-party sources are compiled separately to avoid failing the build under -Werror.

Changes:

• Enable -Wall -Wextra -Werror (with some warning suppressions) for non-MSVC builds.
• Build mini-yaml sources into a new graphar_thirdparty static library and link GraphAr against it.
• Address remaining warnings via copy-assignment operators and type-correct comparisons.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
rust/build.rs	Links Rust FFI build against the new graphar_thirdparty library.
cpp/src/graphar/status.h	Removes redundant move in Status construction.
cpp/src/graphar/arrow/chunk_reader.h	Declares copy assignment operators for chunk reader classes.
cpp/src/graphar/arrow/chunk_reader.cc	Implements the new copy assignment operators.
cpp/examples/mid_level_reader_example.cc	Fixes signed/unsigned comparison warning in assertions.
cpp/CMakeLists.txt	Adds global warning flags and introduces graphar_thirdparty build/install + linkage.

Comments suppressed due to low confidence (2)

cpp/src/graphar/status.h:162

• Status::FromArgs takes parameters by value (Args... args) but then uses std::forward(args)..., which defeats perfect-forwarding and can introduce unnecessary copies. Prefer Args&&... args (forwarding references) so forwarding is correct and efficient.

  template <typename... Args>
  static Status FromArgs(StatusCode code, Args... args) {
    return Status(code, util::StringBuilder(std::forward<Args>(args)...));
  }

cpp/examples/mid_level_reader_example.cc:135

• This compares an int (num_columns()) with a size_t-derived value by narrowing specific_cols.size() to int. Even in an example, it’s safer to avoid narrowing conversions; consider casting num_columns() to size_t (or using a signed size type consistently) to keep the comparison in the wider domain.

  ASSERT(specific_table->num_columns() ==
         static_cast<int>(specific_cols.size()) + 1);

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[Copilot]

AdjListArrowChunkReader::operator=() does not copy prefix_ (but copy-ctor does). After assignment, prefix_ can be stale while base_dir_/fs_ refer to the new object, and methods like seek_src/seek_dst use prefix_ to compute paths, leading to incorrect reads. Copy prefix_ as well (and keep base_dir_ consistent with it).