feat!: File::new_section() and related now returns their id as well.

That way it's possible to more easily interact with it later, for instance
when one wants to delete it.

git-config/src/file/init/mod.rs

@@ -58,6 +58,7 @@ impl<'a> File<'a> {
                 header: section.header,
                 body: section::Body(section.events),
                 meta: OwnShared::clone(&meta),
+                id: Default::default(),
             });
         }
 

git-config/src/file/mod.rs

@@ -72,6 +72,7 @@ pub struct Section<'a> {
     header: crate::parse::section::Header<'a>,
     body: section::Body<'a>,
     meta: OwnShared<Metadata>,
+    id: SectionId,
 }
 
 /// A function to filter metadata, returning `true` if the corresponding but omitted value can be used.
@@ -112,6 +113,12 @@ impl AddAssign<usize> for Size {
 #[derive(PartialEq, Eq, Hash, Copy, Clone, PartialOrd, Ord, Debug)]
 pub struct SectionId(pub(crate) usize);
 
+impl Default for SectionId {
+    fn default() -> Self {
+        SectionId(usize::MAX)
+    }
+}
+
 /// All section body ids referred to by a section name.
 ///
 /// Note that order in Vec matters as it represents the order

git-config/src/file/section/mod.rs

@@ -11,6 +11,7 @@ use crate::{
 };
 
 pub(crate) mod body;
+use crate::file::SectionId;
 pub use body::{Body, BodyIter};
 use git_features::threading::OwnShared;
 
@@ -36,6 +37,7 @@ impl<'a> Section<'a> {
             header: parse::section::Header::new(name, subsection)?,
             body: Default::default(),
             meta: meta.into(),
+            id: SectionId::default(),
         })
     }
 }
@@ -47,6 +49,12 @@ impl<'a> Section<'a> {
         &self.header
     }
 
+    /// Return the unique `id` of the section, for use with the `*_by_id()` family of methods
+    /// in [git_config::File][crate::File].
+    pub fn id(&self) -> SectionId {
+        self.id
+    }
+
     /// Return our body, containing all keys and values.
     pub fn body(&self) -> &Body<'a> {
         &self.body

git-config/src/file/util.rs

@@ -12,8 +12,9 @@ use crate::{
 /// Private helper functions
 impl<'event> File<'event> {
     /// Adds a new section to the config file, returning the section id of the newly added section.
-    pub(crate) fn push_section_internal(&mut self, section: file::Section<'event>) -> SectionId {
+    pub(crate) fn push_section_internal(&mut self, mut section: file::Section<'event>) -> SectionId {
         let new_section_id = SectionId(self.section_id_counter);
+        section.id = new_section_id;
         self.sections.insert(new_section_id, section);
         let header = &self.sections[&new_section_id].header;
         let lookup = self.section_lookup_tree.entry(header.name.clone()).or_default();
@@ -53,7 +54,7 @@ impl<'event> File<'event> {
     }
 
     /// Inserts `section` after the section that comes `before` it, and maintains correct ordering in all of our lookup structures.
-    pub(crate) fn insert_section_after(&mut self, section: file::Section<'event>, before: SectionId) -> SectionId {
+    pub(crate) fn insert_section_after(&mut self, mut section: file::Section<'event>, before: SectionId) -> SectionId {
         let lookup_section_order = {
             let section_order = &self.section_order;
             move |section_id| {
@@ -67,6 +68,7 @@ impl<'event> File<'event> {
 
         let before_order = lookup_section_order(before);
         let new_section_id = SectionId(self.section_id_counter);
+        section.id = new_section_id;
         self.sections.insert(new_section_id, section);
         let header = &self.sections[&new_section_id].header;
         let lookup = self.section_lookup_tree.entry(header.name.clone()).or_default();