Validate inputs for FLOAT/REAL data types

[bilalkah]

Description

T-SQL parity for real/float: reject special literals; add safe casts

• What: String→real/float casts now reject NaN/Infinity/inf (T-SQL doesn’t allow them). TRY_CAST returns NULL instead of accepting those values. Empty strings cast to 0.
• Why: Align Babelfish with T-SQL behavior; avoid downstream errors.
• How (high level):
• Added validator is_valid_tsql_float and used it in varchar2float4/8, bpchar2float4/8.
• Registered explicit casts for pg_catalog.VARCHAR/BPCHAR/TEXT → FLOAT4/FLOAT8 via new sys.*2float* functions.
• Parser/coercion: route TRY_CAST(... AS real|float(p)); float(p) uses real for 1..24, float8 otherwise.
• Exposed is_tsql_real_datatype / is_tsql_float_datatype via common utility plugin.
• Added upgrade scripts to install new casts/functions.

Issues Resolved

https://github.com/babelfish-for-postgresql/babelfish_extensions/issues/4028

Test Scenarios Covered

• CAST('' AS real) → 0; CAST('Infinity' AS float) → error
• TRY_CAST('NaN' AS real) → NULL
• TRY_CAST('123' AS float(24)) → real; float(25) → float8
• Whitespace/exponent forms accepted; non-numeric strings error (or NULL via TRY_CAST)

Check List

• [x] Commits are signed per the DCO using --signoff

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[coveralls]

Pull Request Test Coverage Report for Build 18575071680

Details

• 73 of 79 (92.41%) changed or added relevant lines in 4 files are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.04%) to 76.685%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
contrib/babelfishpg_tsql/src/pltsql_coerce.c	12	13	92.31%
contrib/babelfishpg_common/src/varchar.c	51	56	91.07%
<!--	Total:	73	79

Files with Coverage Reduction	New Missed Lines	%
contrib/babelfishpg_common/src/varchar.c	2	87.94%
contrib/babelfishpg_tds/src/backend/tds/tdscomm.c	2	76.23%
<!--	Total:	4

Totals
Change from base Build 18562751231:	0.04%
Covered Lines:	51803
Relevant Lines:	67553

---

💛 - Coveralls

[bilalkah]

And let's fix the test cases first.

@Yvinayak07 I don't understand. What do you mean?

[bilalkah]

Can you please make a review? @Yvinayak07

[bilalkah]

Hi @Yvinayak07 , Can you please help me understand the upgrade test from version X_Y to latest? As far as I understand, in such test cases, the result should include my changes since it has been upgraded to latest. However, the results are saying that. For example, I need to provide old results in test/JDBC/upgrade/17_7/schedule. Why is that?