[librsvg: 2/10] Clarify the comment in rsvg_g_warning()

[Federico Mena Quintero <federico src gnome org>]

commit e07a99bb6b06b1d800af87b407e86b74cd2be8fe
Author: Federico Mena Quintero <federico gnome org>
Date:   Tue Jul 23 14:25:42 2019 -0500

    Clarify the comment in rsvg_g_warning()

 rsvg_internals/src/util.rs | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)
---
diff --git a/rsvg_internals/src/util.rs b/rsvg_internals/src/util.rs
index e10d301b..0bb4a9bf 100644
--- a/rsvg_internals/src/util.rs
+++ b/rsvg_internals/src/util.rs
@@ -50,10 +50,14 @@ pub fn rsvg_g_warning(msg: &str) {
 
 #[cfg(not(feature = "c-library"))]
 pub fn rsvg_g_warning(_msg: &str) {
-    // The only callers of this are in handle.rs. When those functions
-    // are called from the Rust API, they are able to return a
-    // meaningful error code, but the C API isn't - so they issues a
-    // g_warning() instead.
+    // This, and rsvg_g_critical() below, are intended to be called
+    // from Rust code which is directly called from the C API.  When
+    // this crate is being built as part of the c-library, the purpose
+    // of the functions is to call the corresponding glib macros to
+    // print a warning or a critical error message.  When this crate
+    // is being built as part of the standalone Rust crate, they do
+    // nothing, since the Rust code is able to propagate an error code
+    // all the way to the crate's public API.
 }
 
 #[cfg(feature = "c-library")]