Extend `generated_name_override` callback to variables (#2351)

* This change updates `ParseCallbacks::generated_name_override` to accept a second parameter indicating the kind of item the name applies to (currently, either `Function` or `Var`).
* A `CallbackItemKind` enum was added to serve as the type for this second parameter.
* Tests have been updated to verify that the names of both function and variable can be updated by this callback. 

6 files changed, 72 insertions, 20 deletions

diff --git a/bindgen-tests/tests/expectations/tests/issue-1375-prefixed-functions.rs b/bindgen-tests/tests/expectations/tests/issue-1375-prefixed-functions.rs
index 835b7579..edcca46d 100644
--- a/bindgen-tests/tests/expectations/tests/issue-1375-prefixed-functions.rs
+++ b/bindgen-tests/tests/expectations/tests/issue-1375-prefixed-functions.rs
@@ -6,6 +6,14 @@
 )]
 
 extern "C" {
+    #[link_name = "\u{1}my_custom_prefix_var_const_name"]
+    pub static var_const_name: ::std::os::raw::c_int;
+}
+extern "C" {
+    #[link_name = "\u{1}my_custom_prefix_var_mut_name"]
+    pub static mut var_mut_name: ::std::os::raw::c_int;
+}
+extern "C" {
     #[link_name = "\u{1}my_custom_prefix_function_name"]
     pub fn function_name(x: ::std::os::raw::c_int);
 }
diff --git a/bindgen-tests/tests/headers/issue-1375-prefixed-functions.h b/bindgen-tests/tests/headers/issue-1375-prefixed-functions.h
index 4264e52d..cc37c8ad 100644
--- a/bindgen-tests/tests/headers/issue-1375-prefixed-functions.h
+++ b/bindgen-tests/tests/headers/issue-1375-prefixed-functions.h
@@ -1,4 +1,8 @@
 // bindgen-parse-callbacks: remove-function-prefix-my_custom_prefix_
 
+extern const int my_custom_prefix_var_const_name;
+
+extern int my_custom_prefix_var_mut_name;
+
 void my_custom_prefix_function_name(const int x);
 
diff --git a/bindgen-tests/tests/parse_callbacks/mod.rs b/bindgen-tests/tests/parse_callbacks/mod.rs
index 6ade71c2..00967fe8 100644
--- a/bindgen-tests/tests/parse_callbacks/mod.rs
+++ b/bindgen-tests/tests/parse_callbacks/mod.rs
@@ -1,22 +1,29 @@
 use bindgen::callbacks::*;
 
 #[derive(Debug)]
-pub struct RemoveFunctionPrefixParseCallback {
-    pub remove_function_prefix: Option<String>,
+pub struct RemovePrefixParseCallback {
+    pub remove_prefix: Option<String>,
 }
 
-impl RemoveFunctionPrefixParseCallback {
+impl RemovePrefixParseCallback {
     pub fn new(prefix: &str) -> Self {
-        RemoveFunctionPrefixParseCallback {
-            remove_function_prefix: Some(prefix.to_string()),
+        RemovePrefixParseCallback {
+            remove_prefix: Some(prefix.to_string()),
         }
     }
 }
 
-impl ParseCallbacks for RemoveFunctionPrefixParseCallback {
-    fn generated_name_override(&self, function_name: &str) -> Option<String> {
-        if let Some(prefix) = &self.remove_function_prefix {
-            if let Some(name) = function_name.strip_prefix(prefix) {
+impl ParseCallbacks for RemovePrefixParseCallback {
+    fn generated_name_override(&self, item_info: ItemInfo) -> Option<String> {
+        if let Some(prefix) = &self.remove_prefix {
+            let (expected_prefix, expected_suffix) = match item_info.kind {
+                ItemKind::Function => ("function_", "_name"),
+                ItemKind::Var => ("var_", "_name"),
+                _ => todo!(),
+            };
+            if let Some(name) = item_info.name.strip_prefix(prefix) {
+                assert!(name.starts_with(expected_prefix));
+                assert!(name.ends_with(expected_suffix));
                 return Some(name.to_string());
             }
         }
@@ -67,8 +74,7 @@ pub fn lookup(cb: &str) -> Box<dyn ParseCallbacks> {
                     .split("remove-function-prefix-")
                     .last()
                     .to_owned();
-                let lnopc =
-                    RemoveFunctionPrefixParseCallback::new(prefix.unwrap());
+                let lnopc = RemovePrefixParseCallback::new(prefix.unwrap());
                 Box::new(lnopc)
             } else {
                 panic!("Couldn't find name ParseCallbacks: {}", cb)
diff --git a/bindgen/callbacks.rs b/bindgen/callbacks.rs
index 5e8ac788..1e48a302 100644
--- a/bindgen/callbacks.rs
+++ b/bindgen/callbacks.rs
@@ -30,9 +30,9 @@ pub trait ParseCallbacks: fmt::Debug {
         MacroParsingBehavior::Default
     }
 
-    /// This function will run for every function. The returned value determines the name visible
-    /// in the bindings.
-    fn generated_name_override(&self, _function_name: &str) -> Option<String> {
+    /// This function will run for every extern variable and function. The returned value determines
+    /// the name visible in the bindings.
+    fn generated_name_override(&self, _item_info: ItemInfo) -> Option<String> {
         None
     }
 
@@ -122,3 +122,21 @@ pub struct DeriveInfo<'a> {
     /// The name of the type.
     pub name: &'a str,
 }
+
+/// An struct providing information about the item being passed to `ParseCallbacks::generated_name_override`.
+#[non_exhaustive]
+pub struct ItemInfo<'a> {
+    /// The name of the item
+    pub name: &'a str,
+    /// The kind of item
+    pub kind: ItemKind,
+}
+
+/// An enum indicating the kind of item for an ItemInfo.
+#[non_exhaustive]
+pub enum ItemKind {
+    /// A Function
+    Function,
+    /// A Variable
+    Var,
+}
diff --git a/bindgen/ir/function.rs b/bindgen/ir/function.rs
index ecb3202f..8e83d980 100644
--- a/bindgen/ir/function.rs
+++ b/bindgen/ir/function.rs
@@ -6,6 +6,7 @@ use super::dot::DotAttributes;
 use super::item::Item;
 use super::traversal::{EdgeKind, Trace, Tracer};
 use super::ty::TypeKind;
+use crate::callbacks::{ItemInfo, ItemKind};
 use crate::clang::{self, Attribute};
 use crate::parse::{ClangSubItemParser, ParseError, ParseResult};
 use clang_sys::{self, CXCallingConv};
@@ -712,10 +713,12 @@ impl ClangSubItemParser for Function {
             // but seems easy enough to handle it here.
             name.push_str("_destructor");
         }
-        if let Some(nm) = context
-            .options()
-            .last_callback(|callbacks| callbacks.generated_name_override(&name))
-        {
+        if let Some(nm) = context.options().last_callback(|callbacks| {
+            callbacks.generated_name_override(ItemInfo {
+                name: name.as_str(),
+                kind: ItemKind::Function,
+            })
+        }) {
             name = nm;
         }
         assert!(!name.is_empty(), "Empty function name.");
diff --git a/bindgen/ir/var.rs b/bindgen/ir/var.rs
index 610b9dfa..903e1ff5 100644
--- a/bindgen/ir/var.rs
+++ b/bindgen/ir/var.rs
@@ -7,7 +7,7 @@ use super::function::cursor_mangling;
 use super::int::IntKind;
 use super::item::Item;
 use super::ty::{FloatKind, TypeKind};
-use crate::callbacks::MacroParsingBehavior;
+use crate::callbacks::{ItemInfo, ItemKind, MacroParsingBehavior};
 use crate::clang;
 use crate::clang::ClangToken;
 use crate::parse::{ClangSubItemParser, ParseError, ParseResult};
@@ -272,7 +272,20 @@ impl ClangSubItemParser for Var {
                 ))
             }
             CXCursor_VarDecl => {
-                let name = cursor.spelling();
+                let mut name = cursor.spelling();
+                if cursor.linkage() == CXLinkage_External {
+                    if let Some(nm) = ctx.options().last_callback(|callbacks| {
+                        callbacks.generated_name_override(ItemInfo {
+                            name: name.as_str(),
+                            kind: ItemKind::Var,
+                        })
+                    }) {
+                        name = nm;
+                    }
+                }
+                // No more changes to name
+                let name = name;
+
                 if name.is_empty() {
                     warn!("Empty constant name?");
                     return Err(ParseError::Continue);