Quote Redshift identifiers that would lose their casing

[dylanpulver]

dbt-adapter has two public functions named need_quotes, in different modules, with the argument order swapped. They disagree about Redshift.

need_quotes.rs:

|| (matches!(adapter_type, AdapterType::Snowflake) && id.chars().any(|c| c.is_ascii_lowercase()))
|| (matches!(adapter_type, AdapterType::Redshift) && id.chars().any(|c| c.is_ascii_uppercase()))

format_ident.rs has the Snowflake clause and no Redshift one, so format_ident("MyTable", AdapterType::Redshift) returns MyTable unquoted. Redshift folds unquoted identifiers to lowercase, so the emitted SQL refers to mytable and the casing the Snowflake rule exists to preserve is lost for Redshift.

Both are reachable through the same trait, which is what makes them contradict rather than merely differ. TypeOps in sql_types.rs exposes:

fn format_ident(&self, id: &str) -> String { crate::format_ident::format_ident(id, self.adapter_type()) }
fn need_quotes_for_ident(&self, id: &str) -> bool { need_quotes(self.adapter_type(), id) }

On Redshift, need_quotes_for_ident("MyTable") is true while format_ident("MyTable") returns it unquoted.

This adds the missing Redshift clause to format_ident.rs, mirroring the wording of the Snowflake one, and two tests: one pinning the case-folding behaviour for both backends, and one asserting the two functions agree, so the pair cannot drift apart again silently.

I kept the change to the missing clause rather than collapsing the duplication, per the "keep changes minimal and focused" rule in AGENTS.md. If you would rather have one function and a re-export, I am happy to send that instead.

cargo test -p dbt-adapter --lib format_ident: 12 passed. Reverting the clause fails the new agreement test with format_ident and need_quotes disagree for "MyTable" on Redshift, so it is not passing vacuously. cargo fmt clean.

No changelog entry: changie new wants an issue number and I did not open one, since this looked small enough to bring straight as a PR. Say the word and I will add one.

This PR was written with AI assistance (Claude Code).

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