Replace std::hash namespace std specialization with custom task_ptr_hash

[Copilot]

• Remove std::hash<std::shared_ptr<task>> specialization from namespace std
• Add custom task_ptr_hash struct to task_graph.h
• Add using tasks_set = std::unordered_set<task_ptr, task_ptr_hash> alias
• Update all usages to use tasks_set instead of the verbose type

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[kgorking]

@copilot The type std::unordered_set<task_ptr, task_ptr_hash> has gotten long. Add a 'using tasks_set = ...' and use that instead.

[Copilot]

@copilot The type std::unordered_set<task_ptr, task_ptr_hash> has gotten long. Add a 'using tasks_set = ...' and use that instead.

Done in 3ac1e1f. Added using tasks_set = std::unordered_set<task_ptr, task_ptr_hash>; after the hasher struct, and replaced all occurrences of the verbose type in both the header and source file.

[Copilot]

Pull request overview

This PR removes a std::hash specialization for task_ptr from namespace std and replaces it with a local task_ptr_hash + tasks_set alias, then updates task-graph code to use the new alias/types.

Changes:

• Introduces task_ptr_hash and using tasks_set = std::unordered_set<task_ptr, task_ptr_hash> in task_graph.h
• Updates circular-dependency detection to use tasks_set instead of std::unordered_set<task_ptr>
• Updates task_name_map to use task_ptr_hash explicitly for unordered_map<task_ptr, ...>

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
gbs/inc/task/task_graph.h	Removes std::hash specialization; adds task_ptr_hash, tasks_set, and applies hash to task_name_map.
gbs/src/task/task_graph.cpp	Switches visited set type to tasks_set in circular-dependency detection and dependency insertion.
gbs/src/cmd_build.cpp	Adds a global std::mutex declaration (currently unused).

Comments suppressed due to low confidence (1)

gbs/src/task/task_graph.cpp:71

• The circular-dependency branch no longer exits early, so the dependency is still added after printing the error. This effectively allows cycles and will likely cause incorrect scheduling/termination behavior. Restore an early return (or otherwise abort/throw) when a circular path is detected so the edge is not inserted.

		std::println("  '{}' (would create cycle)", parent_name);
	}

	child->deps.fetch_add(1, std::memory_order_relaxed);
	parent->children.push_back(child);

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