fix: function dump default

[tianzhou]

Fix #125

[Copilot]

Pull Request Overview

This PR fixes GitHub issue #125 where function parameter default values were being lost when dumping functions from the database. The fix simplifies parameter parsing by relying solely on pg_get_function_arguments() which already includes complete parameter information including defaults, rather than using a dual-path approach with PostgreSQL system catalog arrays.

Key Changes:

• Removed the parseParametersFromProcArrays method and its associated system catalog queries
• Simplified parameter parsing to use only parseParametersFromSignature which processes the complete signature from pg_get_function_arguments()
• Added comprehensive test coverage with 5 test cases covering simple defaults, mixed IN/OUT parameters, INOUT parameters, complex default expressions, and VARIADIC parameters

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
testdata/dump/issue_125_function_default/raw.sql	Adds test cases with functions using various parameter default patterns
testdata/dump/issue_125_function_default/pgschema.sql	Expected output showing preserved default values in dumped functions
testdata/dump/issue_125_function_default/pgdump.sql	Reference pg_dump output for comparison
testdata/dump/issue_125_function_default/manifest.json	Test metadata describing the issue being tested
ir/queries/queries.sql	Removes unused system catalog array fields from function query
ir/inspector.go	Removes dual-path parameter parsing, uses only signature-based parsing
cmd/dump/dump_integration_test.go	Adds integration test for issue #125

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[Copilot]

The default value DEFAULT NULL differs from the input in raw.sql which specifies DEFAULT NULL::text. The explicit cast to text should be preserved to match PostgreSQL's behavior and pg_dump's output (line 36 in pgdump.sql shows DEFAULT NULL::text).

Suggested change

	p_schema_override text DEFAULT NULL,
	p_schema_override text DEFAULT NULL::text,

[Copilot]

The default value DEFAULT NULL is missing the explicit type cast. According to pgdump.sql line 49, this should be DEFAULT NULL::numeric to properly specify the typed null value.

Suggested change

	INOUT result numeric DEFAULT NULL
	INOUT result numeric DEFAULT NULL::numeric