Function invent

src/sql/src/plan/query.rs:3529–3625

(
        ecx: &ExprContext,
        expr: &Expr<Aug>,
        table_func_names: &BTreeMap<String, Ident>,
    )

    }

    fn invent(
        ecx: &ExprContext,
        expr: &Expr<Aug>,
        table_func_names: &BTreeMap<String, Ident>,
    ) -> Result<Option<(ColumnName, NameQuality)>, PlanError> {
        Ok(match expr {
            Expr::Identifier(names) => {
                if let [name] = names.as_slice() {
                    if let Some(table_func_name) = table_func_names.get(name.as_str()) {
                        return Ok(Some((
                            normalize::column_name(table_func_name.clone()),
                            NameQuality::High,
                        )));
                    }
                }
                names
                    .last()
                    .map(|n| (normalize::column_name(n.clone()), NameQuality::High))
            }
            Expr::Value(v) => match v {
                // Per PostgreSQL, `bool` and `interval` literals take on the name
                // of their type, but not other literal types.
                Value::Boolean(_) => Some(("bool".into(), NameQuality::High)),
                Value::Interval(_) => Some(("interval".into(), NameQuality::High)),
                _ => None,
            },
            Expr::Function(func) => {
                let (schema, item) = match &func.name {
                    ResolvedItemName::Item {
                        qualifiers,
                        full_name,
                        ..
                    } => (&qualifiers.schema_spec, full_name.item.clone()),
                    // Name resolution should have rejected anything other than
                    // `Item` for a function call.
                    _ => {
                        bail_internal!("function name did not resolve to an item: {:?}", func.name)
                    }
                };

                if schema == &SchemaSpecifier::from(ecx.qcx.scx.catalog.get_mz_internal_schema_id())
                    || schema
                        == &SchemaSpecifier::from(ecx.qcx.scx.catalog.get_mz_unsafe_schema_id())
                {
                    None
                } else {
                    Some((item.into(), NameQuality::High))
                }
            }
            Expr::HomogenizingFunction { function, .. } => Some((
                function.to_string().to_lowercase().into(),
                NameQuality::High,
            )),
            Expr::NullIf { .. } => Some(("nullif".into(), NameQuality::High)),
            Expr::Array { .. } => Some(("array".into(), NameQuality::High)),
            Expr::List { .. } => Some(("list".into(), NameQuality::High)),
            Expr::Map { .. } | Expr::MapSubquery(_) => Some(("map".into(), NameQuality::High)),
            Expr::Cast { expr, data_type } => match invent(ecx, expr, table_func_names)? {