Add dummy symbols to empty sections

Allows diffing sections without symbols

Resolves #87

objdiff-core/src/diff/mod.rs

@@ -612,6 +612,20 @@ fn matching_symbols(
     Ok(matches)
 }
 
+fn unmatched_symbols<'section, 'used>(
+    section: &'section ObjSection,
+    section_idx: usize,
+    used: Option<&'used HashSet<SymbolRef>>,
+) -> impl Iterator<Item = (usize, &'section ObjSymbol)> + 'used
+where
+    'section: 'used,
+{
+    section.symbols.iter().enumerate().filter(move |&(symbol_idx, _)| {
+        // Skip symbols that have already been matched
+        !used.map(|u| u.contains(&SymbolRef { section_idx, symbol_idx })).unwrap_or(false)
+    })
+}
+
 fn find_symbol(
     obj: Option<&ObjInfo>,
     in_symbol: &ObjSymbol,
@@ -624,8 +638,8 @@ fn find_symbol(
         if section.kind != in_section.kind {
             continue;
         }
-        if let Some(symbol_idx) =
-            section.symbols.iter().position(|symbol| symbol.name == in_symbol.name)
+        if let Some((symbol_idx, _)) = unmatched_symbols(section, section_idx, used)
+            .find(|(_, symbol)| symbol.name == in_symbol.name)
         {
             return Some(SymbolRef { section_idx, symbol_idx });
         }
@@ -638,9 +652,11 @@ fn find_symbol(
         if let Some((section_idx, section)) =
             obj.sections.iter().enumerate().find(|(_, s)| s.name == in_section.name)
         {
-            if let Some(symbol_idx) = section.symbols.iter().position(|symbol| {
+            if let Some((symbol_idx, _)) =
+                unmatched_symbols(section, section_idx, used).find(|(_, symbol)| {
                     symbol.address == in_symbol.address && symbol.name.starts_with('@')
-            }) {
+                })
+            {
                 return Some(SymbolRef { section_idx, symbol_idx });
             }
         }
@@ -655,13 +671,7 @@ fn find_symbol(
                 continue;
             }
             if let Some((symbol_idx, _)) =
-                section.symbols.iter().enumerate().find(|&(symbol_idx, symbol)| {
-                    if used
-                        .map(|u| u.contains(&SymbolRef { section_idx, symbol_idx }))
-                        .unwrap_or(false)
-                    {
-                        return false;
-                    }
+                unmatched_symbols(section, section_idx, used).find(|&(_, symbol)| {
                     if let Some((p, s)) = symbol.name.split_once('$') {
                         prefix == p && s.chars().all(char::is_numeric)
                     } else {

objdiff-core/src/obj/read.rs

@@ -160,6 +160,23 @@ fn symbols_by_section(
             }
         }
     }
+    if result.is_empty() {
+        // Dummy symbol for empty sections
+        result.push(ObjSymbol {
+            name: format!("[{}]", section.name),
+            demangled_name: None,
+            has_extab: false,
+            extab_name: None,
+            extabindex_name: None,
+            address: 0,
+            section_address: 0,
+            size: section.size,
+            size_known: true,
+            flags: Default::default(),
+            addend: 0,
+            virtual_address: None,
+        });
+    }
     Ok(result)
 }
 

objdiff-gui/src/views/symbol_diff.rs

@@ -233,6 +233,7 @@ fn symbol_ui(
     {
         selected = symbol_diff.symbol_ref == sym_ref;
     }
+    if !symbol.flags.0.is_empty() {
         write_text("[", appearance.text_color, &mut job, appearance.code_font.clone());
         if symbol.flags.0.contains(ObjSymbolFlags::Common) {
             write_text("c", appearance.replace_color, &mut job, appearance.code_font.clone());
@@ -248,6 +249,7 @@ fn symbol_ui(
             write_text("h", appearance.deemphasized_text_color, &mut job, appearance.code_font.clone());
         }
         write_text("] ", appearance.text_color, &mut job, appearance.code_font.clone());
+    }
     if let Some(match_percent) = symbol_diff.match_percent {
         write_text("(", appearance.text_color, &mut job, appearance.code_font.clone());
         write_text(