refactor(clang-tidy): behaviour-preserving modernize sweep of CoolPropLib.cpp (CoolProp-jtl)

[ibell]

Resolves beads CoolProp-jtl. Continues the #2926 / CoolProp-2uw clang-tidy modernize series.

What

Clears the 24 whole-file clang-tidy signal findings in src/CoolPropLib.cpp that were surfaced while running preflight for #2873 (PR #2983). All changes are behaviour-preserving.

Check	Sites	Fix
clang-analyzer-security.insecureAPI.strcpy	7	strcpy → std::memcpy(dst, s.c_str(), s.size()+1)
readability-implicit-bool-conversion	6	return true/false → 1/0; explicit static_cast for bool→long/int
modernize-raw-string-literal	4	escaped-quote format strings → R"(...)"
modernize-use-scoped-lock	3	std::lock_guard<std::mutex> → std::scoped_lock
*-use-default-member-init	1	AbstractStateLibrary::next_handle in-class init + ctor = default
performance-unnecessary-value-param	1	add() takes shared_ptr by const ref
modernize-use-auto	1	map iterator → auto
cppcoreguidelines-special-member-functions	1	fpu_reset_guard declares deleted copy/move (RAII scope guard)

Why the strcpy → memcpy change is safe (not just silencing)

Every strcpy site was already guarded by a preceding if (s.size() < buffer_length) with strict < against the buffer-length variable that bounds the destination buffer. So s.size() + 1 <= buffer_length, and memcpy of size + null terminator always fits — byte-identical behaviour, minus the categorically-banned strcpy. (Confirmed per-site, including AbstractState_fluid_param_string correctly using return_buffer_length rather than the unrelated message_buffer/buffer_length.)

Deliberately out of scope

cppcoreguidelines-pro-bounds-pointer-arithmetic findings are left untouched — they sit in preflight's noise-filter and CI does not enforce them on this inherently pointer-based array C API.

Verification

• ✅ Preflight green: clang-format, build, Catch2 tests, cppcheck, clang-tidy 0 signal findings, semgrep.
• ✅ Adversarial pre-PR review: no blocking findings (memcpy guard-correspondence, raw-string byte-equality, scoped_lock semantics, const-ref safety, and fpu_reset_guard never-copied all individually verified).

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Improved error message handling and reporting reliability
  • Enhanced buffer safety across library operations
  • Increased stability through safer memory handling in state-setter functions

[coderabbitai]

Caution

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Pull request was closed or merged during review

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ℹ️ Recent review info

⚙️ Run configuration

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Review profile: CHILL

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Run ID: 4f296c9d-6be0-4f44-9ce3-7f2603dfe0ea

📥 Commits

Reviewing files that changed from the base of the PR and between e92a71a and 1d255c7.

📒 Files selected for processing (1)

• src/CoolPropLib.cpp

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📝 Walkthrough

Walkthrough

This PR improves buffer safety and type consistency in CoolProp's C-API layer (src/CoolPropLib.cpp). Error handling now uses bounded memcpy instead of unsafe strcpy, internal handle management is refactored with safer synchronization, reference-state setters return integer codes for error indication, and multiple string-output functions apply the same safe-copy pattern. Error messages adopt raw-string literals for clarity.

Changes

CoolProp C-API Buffer Safety and Type Safety

Layer / File(s)	Summary
Error handling and resource lifetime src/CoolPropLib.cpp	HandleException replaces strcpy with std::memcpy for writing exception messages into message_buffer under existing length checks. fpu_reset_guard is made explicitly non-copyable and non-movable by deleting copy/move constructors and assignment operators.
AbstractStateLibrary handle management refactoring src/CoolPropLib.cpp	AbstractStateLibrary is refactored to default-initialize next_handle as a member, use std::scoped_lock for synchronization, and pass shared_ptr by const reference in the add method instead of by value.
String buffer copying safety across C-API functions src/CoolPropLib.cpp	AbstractState_fluid_names, AbstractState_backend_name, AbstractState_fluid_param_string, and C_extract_backend replace strcpy with std::memcpy when writing composed or formatted strings into caller-provided buffers, copying size()+1 bytes under existing bounds checks.
Reference state setter return codes src/CoolPropLib.cpp	set_reference_stateS and set_reference_stateD change from void functions to return integer success codes (1 on success, 0 on failure), while preserving exception handling and error-string assignment in catch blocks.
String formatting and output type casts src/CoolPropLib.cpp	get_parameter_information_string adopts raw-string literal formatting for error messages; AbstractState_get_mole_fractions_satState and AbstractState_keyed_output_satState update error messages to raw-string literals; AbstractState_all_critical_points casts pts[i].stable to long when writing output; C_is_valid_fluid_string explicitly casts boolean result to int.

Poem

🐰 Whiskers twitching with delight—
Buffer bounds now safe and tight!
No more strcpy troubles brew,
Memcpy takes the safer route true.
Types cast clear, handles shine,
CoolProp's C-API now divine!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: a modernization refactoring of CoolPropLib.cpp to fix clang-tidy findings while preserving behavior.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ihb/clang-tidy-coolproplib-jtl

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