Fix debug information relocation (when imports present) (#1997)

crates/obj/src/builder.rs

@@ -448,7 +448,9 @@ impl<'a> ObjectBuilder<'a> {
             let section_id = *dwarf_sections_ids.get(name).unwrap();
             for reloc in relocs {
                 let target_symbol = match reloc.target {
-                    DwarfSectionRelocTarget::Func(index) => func_symbols[FuncIndex::new(index)],
+                    DwarfSectionRelocTarget::Func(index) => {
+                        func_symbols[module.local.func_index(DefinedFuncIndex::new(index))]
+                    }
                     DwarfSectionRelocTarget::Section(name) => {
                         obj.section_symbol(*dwarf_sections_ids.get(name).unwrap())
                     }

tests/all/debug/testsuite/fraction-norm.cc

@@ -1,6 +1,6 @@
 // Compile with:
-//   clang++ --target=wasm32 fraction-norm.cc -o fraction-norm.wasm -g \
-//     -O0 -nostdlib -fdebug-prefix-map=$PWD=.
+//   clang++ --target=wasm32-wasi fraction-norm.cc -o fraction-norm.wasm -g \
+//     -O0 -fdebug-prefix-map=$PWD=.
 
 struct Fraction {
   long numerator;
@@ -32,9 +32,9 @@ void norm(Fraction &n)
   }
 }
 
-extern "C"
-void _start()
+int main()
 {
   Fraction c = {6, 27};
   norm(c);
+  return 0;
 }