Support in FromDatum for binary coercible types (including domain types)

pgx-pg-sys/include/pg11.h

@@ -82,6 +82,7 @@ Use of this source code is governed by the MIT license that can be found in the
 #include "parser/parse_func.h"
 #include "parser/parse_oper.h"
 #include "parser/parse_type.h"
+#include "parser/parse_coerce.h"
 #include "parser/parser.h"
 #include "parser/parsetree.h"
 #include "postmaster/bgworker.h"

pgx-pg-sys/include/pg12.h

@@ -82,6 +82,7 @@ Use of this source code is governed by the MIT license that can be found in the
 #include "parser/parse_func.h"
 #include "parser/parse_oper.h"
 #include "parser/parse_type.h"
+#include "parser/parse_coerce.h"
 #include "parser/parser.h"
 #include "parser/parsetree.h"
 #include "postmaster/bgworker.h"

pgx-pg-sys/include/pg13.h

@@ -82,6 +82,7 @@ Use of this source code is governed by the MIT license that can be found in the
 #include "parser/parse_func.h"
 #include "parser/parse_oper.h"
 #include "parser/parse_type.h"
+#include "parser/parse_coerce.h"
 #include "parser/parser.h"
 #include "parser/parsetree.h"
 #include "postmaster/bgworker.h"

pgx-pg-sys/include/pg14.h

@@ -82,6 +82,7 @@ Use of this source code is governed by the MIT license that can be found in the
 #include "parser/parse_func.h"
 #include "parser/parse_oper.h"
 #include "parser/parse_type.h"
+#include "parser/parse_coerce.h"
 #include "parser/parser.h"
 #include "parser/parsetree.h"
 #include "postmaster/bgworker.h"

pgx-pg-sys/include/pg15.h

@@ -82,6 +82,7 @@ Use of this source code is governed by the MIT license that can be found in the
 #include "parser/parse_func.h"
 #include "parser/parse_oper.h"
 #include "parser/parse_type.h"
+#include "parser/parse_coerce.h"
 #include "parser/parser.h"
 #include "parser/parsetree.h"
 #include "postmaster/bgworker.h"

pgx-tests/src/tests/spi_tests.rs

@@ -459,4 +459,23 @@ mod tests {
         assert_eq!(with_select, with_get_one);
         Ok(())
     }
+
+    #[pg_test]
+    fn spi_can_read_domain_types() -> spi::Result<Option<String>> {
+        Spi::run("CREATE DOMAIN my_text_type TEXT")?;
+        Spi::get_one::<String>("SELECT 'hello'::my_text_type")
+    }
+
+    #[pg_test]
+    fn spi_can_read_domain_types_based_on_domain_types() -> spi::Result<Option<String>> {
+        Spi::run("CREATE DOMAIN my_text_type TEXT")?;
+        Spi::run("CREATE DOMAIN my_other_text_type my_text_type")?;
+        Spi::get_one::<String>("SELECT 'hello'::my_other_text_type")
+    }
+
+    #[pg_test]
+    fn spi_can_read_binary_coercible_types() -> spi::Result<Option<pgx::Inet>> {
+        // cidr is binary coercible to inet
+        Spi::get_one::<pgx::Inet>("select '10.0.0.1/32'::cidr")
+    }
 }

pgx/src/datum/from.rs

@@ -117,7 +117,7 @@ pub trait FromDatum {
     where
         Self: Sized + IntoDatum,
     {
-        if !Self::is_compatible_with(type_oid) {
+        if !is_binary_coercible::<Self>(type_oid) {
             Err(TryFromDatumError::IncompatibleTypes {
                 rust_type: std::any::type_name::<Self>(),
                 rust_oid: Self::type_oid(),
@@ -140,7 +140,7 @@ pub trait FromDatum {
     where
         Self: Sized + IntoDatum,
     {
-        if !Self::is_compatible_with(type_oid) {
+        if !is_binary_coercible::<Self>(type_oid) {
             Err(TryFromDatumError::IncompatibleTypes {
                 rust_type: std::any::type_name::<Self>(),
                 rust_oid: Self::type_oid(),
@@ -153,6 +153,10 @@ pub trait FromDatum {
     }
 }
 
+fn is_binary_coercible<T: IntoDatum>(type_oid: pg_sys::Oid) -> bool {
+    T::is_compatible_with(type_oid) || unsafe { pg_sys::IsBinaryCoercible(type_oid, T::type_oid()) }
+}
+
 /// Retrieves a Postgres type name given its Oid
 pub(crate) fn lookup_type_name(oid: pg_sys::Oid) -> String {
     unsafe {