Address pg16 rename of *_tree_walker fn (#1596)

These functions had been renamed in Postgres 16, and they are now fn
macros. That means this `extern "C"` declaration is simply incorrect in
Postgres 16. Implement a relatively logical version-by-version handling.

Fixes #1583.

pgrx-pg-sys/build.rs

@@ -741,7 +741,7 @@ fn add_blocklists(bind: bindgen::Builder) -> bindgen::Builder {
     bind.blocklist_type("Datum") // manually wrapping datum for correctness
         .blocklist_type("Oid") // "Oid" is not just any u32
         .blocklist_function("varsize_any") // pgrx converts the VARSIZE_ANY macro, so we don't want to also have this function, which is in heaptuple.c
-        .blocklist_function("(?:query|expression)_tree_walker")
+        .blocklist_function("(?:raw_)?(?:query|expression)_tree_walker")
         .blocklist_function(".*(?:set|long)jmp")
         .blocklist_function("pg_re_throw")
         .blocklist_function("err(start|code|msg|detail|context_msg|hint|finish)")

pgrx-pg-sys/src/port.rs

@@ -1,7 +1,6 @@
 use crate as pg_sys;
 
 use memoffset::*;
-use pgrx_macros::pg_guard;
 use std::str::FromStr;
 
 /// this comes from `postgres_ext.h`
@@ -229,29 +228,70 @@ pub unsafe fn heap_tuple_get_struct<T>(htup: super::HeapTuple) -> *mut T {
     }
 }
 
-#[pg_guard]
+// All of this weird code is in response to Postgres having a relatively cavalier attitude about types:
+// - https://github.com/postgres/postgres/commit/1c27d16e6e5c1f463bbe1e9ece88dda811235165
+//
+// As a result, we redeclare their functions with the arguments they should have on earlier Postgres
+// and we route people to the old symbols they were using before on later ones.
+#[cfg(any(feature = "pg12", feature = "pg13", feature = "pg14", feature = "pg15"))]
+#[::pgrx_macros::pg_guard]
 extern "C" {
     pub fn query_tree_walker(
         query: *mut super::Query,
-        walker: ::std::option::Option<
-            unsafe extern "C" fn(*mut super::Node, *mut ::std::os::raw::c_void) -> bool,
+        walker: ::core::option::Option<
+            unsafe extern "C" fn(*mut super::Node, *mut ::core::ffi::c_void) -> bool,
         >,
-        context: *mut ::std::os::raw::c_void,
-        flags: ::std::os::raw::c_int,
+        context: *mut ::core::ffi::c_void,
+        flags: ::core::ffi::c_int,
     ) -> bool;
-}
 
-#[pg_guard]
-extern "C" {
     pub fn expression_tree_walker(
         node: *mut super::Node,
-        walker: ::std::option::Option<
-            unsafe extern "C" fn(*mut super::Node, *mut ::std::os::raw::c_void) -> bool,
+        walker: ::core::option::Option<
+            unsafe extern "C" fn(*mut super::Node, *mut ::core::ffi::c_void) -> bool,
+        >,
+        context: *mut ::core::ffi::c_void,
+    ) -> bool;
+
+    pub fn raw_expression_tree_walker(
+        node: *mut super::Node,
+        walker: ::core::option::Option<
+            unsafe extern "C" fn(*mut super::Node, *mut ::core::ffi::c_void) -> bool,
         >,
-        context: *mut ::std::os::raw::c_void,
+        context: *mut ::core::ffi::c_void,
     ) -> bool;
 }
 
+#[cfg(feature = "pg16")]
+pub unsafe fn query_tree_walker(
+    query: *mut super::Query,
+    walker: ::core::option::Option<
+        unsafe extern "C" fn(*mut super::Node, *mut ::core::ffi::c_void) -> bool,
+    >,
+    context: *mut ::core::ffi::c_void,
+    flags: ::core::ffi::c_int,
+) -> bool {
+    crate::query_tree_walker_impl(query, walker, context, flags)
+}
+
+#[cfg(feature = "pg16")]
+pub unsafe fn expression_tree_walker(
+    arg_node: *mut crate::Node,
+    arg_walker: Option<unsafe extern "C" fn(*mut crate::Node, *mut ::core::ffi::c_void) -> bool>,
+    arg_context: *mut ::core::ffi::c_void,
+) -> bool {
+    crate::expression_tree_walker_impl(arg_node, arg_walker, arg_context)
+}
+
+#[cfg(feature = "pg16")]
+pub unsafe fn raw_expression_tree_walker(
+    arg_node: *mut crate::Node,
+    arg_walker: Option<unsafe extern "C" fn(*mut crate::Node, *mut ::core::ffi::c_void) -> bool>,
+    arg_context: *mut ::core::ffi::c_void,
+) -> bool {
+    crate::raw_expression_tree_walker_impl(arg_node, arg_walker, arg_context)
+}
+
 #[inline(always)]
 pub unsafe fn MemoryContextSwitchTo(context: crate::MemoryContext) -> crate::MemoryContext {
     let old = crate::CurrentMemoryContext;

pgrx-tests/src/tests/pg_try_tests.rs

@@ -7,48 +7,24 @@
 //LICENSE All rights reserved.
 //LICENSE
 //LICENSE Use of this source code is governed by the MIT license that can be found in the LICENSE file.
+use core::ptr;
 use pgrx::prelude::*;
 
 // if our Postgres ERROR and Rust panic!() handling is incorrect, this little bit of useless code
 // will crash postgres.  If things are correct it'll simply raise an ERROR saying "panic in walker".
 #[pg_extern]
 fn crash() {
-    #[cfg(feature = "cshim")]
-    {
-        use pgrx::PgList;
-        let mut node = PgList::<pg_sys::Node>::new();
-        node.push(PgList::<pg_sys::Node>::new().into_pg() as *mut pg_sys::Node);
-
-        #[cfg(any(feature = "pg12", feature = "pg13", feature = "pg14", feature = "pg15"))]
-        unsafe {
-            pg_sys::raw_expression_tree_walker(
-                node.into_pg() as *mut pg_sys::Node,
-                Some(walker),
-                std::ptr::null_mut(),
-            );
-        }
-
-        #[cfg(feature = "pg16")]
-        error!("panic in walker");
-    }
+    use pgrx::{list::List, memcx};
+    memcx::current_context(|current| unsafe {
+        let mut list = List::downcast_ptr_in_memcx(ptr::null_mut(), current).unwrap();
+        list.unstable_push_in_context(ptr::null_mut(), current);
 
-    #[cfg(not(feature = "cshim"))]
-    {
-        walker();
-    }
-}
-
-#[cfg(not(feature = "cshim"))]
-fn walker() -> bool {
-    panic!("panic in walker");
+        pg_sys::raw_expression_tree_walker(list.as_mut_ptr().cast(), Some(walker), ptr::null_mut());
+    });
 }
 
-#[cfg(all(
-    feature = "cshim",
-    any(feature = "pg12", feature = "pg13", feature = "pg14", feature = "pg15")
-))]
 #[pg_guard]
-extern "C" fn walker() -> bool {
+extern "C" fn walker(_node: *mut pg_sys::Node, _void: *mut ::core::ffi::c_void) -> bool {
     panic!("panic in walker");
 }