Function find_function_in_ast 

pub fn find_function_in_ast<'a>(
    ast: &'a File,
    metric_name: &str,
    line: usize,
) -> Option<FoundFunction<'a>>

Find a function in the AST by name and line number.

Searches both top-level functions (syn::Item::Fn) and methods inside impl blocks (syn::Item::Impl -> syn::ImplItem::Fn).

Name Matching

The metric_name parameter may be in one of two formats:

• Simple name: "method_name" (for top-level functions)
• Qualified name: "TypeName::method_name" (for impl methods)

For impl methods, we match if either:

• The metric name equals the simple method name
• The metric name ends with ::method_name

Spec 213

This function is used by the fallback purity analysis path when pre-extracted data is not available. When with_extracted_data() is called on the builder, this function is not used. It’s kept for backward compatibility with non-parallel analysis paths and testing.