function_exists() — internals

function_exists() — internals

Where it lives

• Signature: src/builtins/callables/function_exists.rs
• Lowering: src/codegen/lower_inst/builtins.rs:568 (lower_function_exists)
• Function symbol: lower_function_exists()

Lowering notes

• Lowers function_exists("name") for compile-time string names.
• Recognizes user functions, externs, catalog builtins, and the date/time procedural aliases
• that name_resolver desugars (including the injected timezone-introspection prelude
• functions). The aliases are matched through is_date_procedural_alias rather than the catalog
• because their call sites are rewritten before codegen, so they never reach the builtin catalog
• yet must still report as existing to match PHP.

Runtime helpers

No direct __rt_* helpers captured — the lowering is inlined or routes through another builtin.

Signature summary

function function_exists(string $function): bool

What the type checker enforces

• Arity: takes exactly 1 argument.

Eval interpreter (magician)

• Declaration: crates/elephc-magician/src/interpreter/builtins/symbols/function_exists.rs (eval_builtin!)
• Dispatch hooks: direct, values

Cross-references

• User reference for function_exists()