Address concerns in pullrequests.

Cargo.lock

@@ -489,6 +489,7 @@ dependencies = [
 name = "cranelift-object"
 version = "0.64.0"
 dependencies = [
+ "anyhow",
  "cranelift-codegen",
  "cranelift-module",
  "object",

cranelift/faerie/src/backend.rs

@@ -211,10 +211,12 @@ impl Backend for FaerieBackend {
             ref data_decls,
             ref function_relocs,
             ref data_relocs,
-            section: ref datasection,
+            ref custom_segment_section,
         } = data_ctx.description();
 
-        assert!(datasection.is_none(), "Custom sections not supported");
+        if let Some((segment, section)) = custom_segment_section {
+            return Err(cranelift_module::ModuleError::Backend(anyhow::anyhow!("Custom section not supported by cranelift-faerie: `{}:{}`", segment, section)));
+        }
 
         for &(offset, id) in function_relocs {
             let to = &namespace.get_function_decl(&function_decls[id]).name;

cranelift/module/src/data_context.rs

@@ -3,7 +3,9 @@
 use cranelift_codegen::binemit::{Addend, CodeOffset};
 use cranelift_codegen::entity::PrimaryMap;
 use cranelift_codegen::ir;
+use std::borrow::ToOwned;
 use std::boxed::Box;
+use std::string::String;
 use std::vec::Vec;
 
 /// This specifies how data is to be initialized.
@@ -47,7 +49,7 @@ pub struct DataDescription {
     /// Data addresses to write at specified offsets.
     pub data_relocs: Vec<(CodeOffset, ir::GlobalValue, Addend)>,
     /// Object file section
-    pub section: Option<(std::string::String, std::string::String)>,
+    pub custom_segment_section: Option<(String, String)>,
 }
 
 /// This is to data objects what cranelift_codegen::Context is to functions.
@@ -65,7 +67,7 @@ impl DataContext {
                 data_decls: PrimaryMap::new(),
                 function_relocs: vec![],
                 data_relocs: vec![],
-                section: None,
+                custom_segment_section: None,
             },
         }
     }
@@ -94,10 +96,10 @@ impl DataContext {
     }
 
     /// Override the segment/section for data, only supported on Object backend
-    pub fn set_section(&mut self, seg: &str, sec: &str) {
+    pub fn set_segment_section(&mut self, seg: &str, sec: &str) {
-        self.description.section = Some((
+        self.description.custom_segment_section = Some((
-            std::string::String::from(seg),
+            seg.to_owned(),
-            std::string::String::from(sec),
+            sec.to_owned(),
         ))
     }
 

cranelift/object/Cargo.toml

@@ -14,6 +14,7 @@ cranelift-module = { path = "../module", version = "0.64.0" }
 cranelift-codegen = { path = "../codegen", version = "0.64.0", default-features = false, features = ["std"] }
 object = { version = "0.18", default-features = false, features = ["write"] }
 target-lexicon = "0.10"
+anyhow = "1.0"
 
 [badges]
 maintenance = { status = "experimental" }

cranelift/object/src/backend.rs

@@ -234,7 +234,7 @@ impl Backend for ObjectBackend {
             ref data_decls,
             ref function_relocs,
             ref data_relocs,
-            section: ref datasection,
+            ref custom_segment_section,
         } = data_ctx.description();
 
         let reloc_size = match self.isa.triple().pointer_width().unwrap() {
@@ -265,7 +265,7 @@ impl Backend for ObjectBackend {
         }
 
         let symbol = self.data_objects[data_id].unwrap();
-        let section = if datasection.is_none() {
+        let section = if custom_segment_section.is_none() {
             let section_kind = if let Init::Zeros { .. } = *init {
                 if tls {
                     StandardSection::UninitializedTls
@@ -283,8 +283,10 @@ impl Backend for ObjectBackend {
             };
             self.object.section_id(section_kind)
         } else {
-            assert!(!tls, "Tls data cannot be in named section");
+            if tls {
-            let (seg, sec) = &datasection.as_ref().unwrap();
+                return Err(cranelift_module::ModuleError::Backend(anyhow::anyhow!("Custom section not supported for TLS")));
+            }
+            let (seg, sec) = &custom_segment_section.as_ref().unwrap();
             self.object.add_section(
                 seg.clone().into_bytes(),
                 sec.clone().into_bytes(),

cranelift/simplejit/src/backend.rs

@@ -361,11 +361,9 @@ impl<'simple_jit_backend> Backend for SimpleJITBackend {
             ref data_decls,
             ref function_relocs,
             ref data_relocs,
-            section: ref datasection,
+            custom_segment_section: _,
         } = data.description();
 
-        assert!(datasection.is_none(), "Custom sections not supported");
-
         let size = init.size();
         let storage = if writable {
             self.memory