Linking: report multiple conflicts

Previously, linking would fail with an exception upon the first symbol
with conflicting types. As there may be multiple problems found in the
same linking run, display all conflicts to the user so that they can fix
all of them at once.

Author: tautschnig

regression/ansi-c/linking_conflicts1/main.c

@@ -0,0 +1,14 @@
+int bar()
+{
+  return 0;
+}
+
+int bar2()
+{
+  return 0;
+}
+
+int main()
+{
+  unsigned x = foo();
+}

regression/ansi-c/linking_conflicts1/other.c

@@ -0,0 +1,12 @@
+void bar()
+{
+}
+
+void bar2()
+{
+}
+
+unsigned foo()
+{
+  return 0;
+}

regression/ansi-c/linking_conflicts1/test.desc

@@ -0,0 +1,10 @@
+CORE
+main.c
+other.c
+^EXIT=(64|1)$
+^SIGNAL=0$
+^CONVERSION ERROR$
+error: conflicting function declarations `bar'
+error: conflicting function declarations `bar2'
+--
+^warning: ignoring

src/linking/linking.cpp

@@ -382,8 +382,6 @@ void linkingt::link_error(
   error() << "new definition in module `" << new_symbol.module
           << "' " << new_symbol.location << '\n'
           << type_to_string_verbose(ns, new_symbol) << eom;
-
-  throw 0;
 }
 
 void linkingt::link_warning(
@@ -573,6 +571,9 @@ void linkingt::duplicate_code_symbol(
         old_symbol,
         new_symbol,
         "conflicting parameter counts of function declarations");
+
+      // error logged, continue typechecking other symbols
+      return;
     }
     else
     {
@@ -602,19 +603,31 @@ void linkingt::duplicate_code_symbol(
       if(o_it!=old_t.parameters().end())
       {
         if(!new_t.has_ellipsis() && old_symbol.value.is_not_nil())
+        {
           link_error(
             old_symbol,
             new_symbol,
             "conflicting parameter counts of function declarations");
+
+          // error logged, continue typechecking other symbols
+          return;
+        }
+
         replace=new_symbol.value.is_not_nil();
       }
       else if(n_it!=new_t.parameters().end())
       {
         if(!old_t.has_ellipsis() && new_symbol.value.is_not_nil())
+        {
           link_error(
             old_symbol,
             new_symbol,
             "conflicting parameter counts of function declarations");
+
+          // error logged, continue typechecking other symbols
+          return;
+        }
+
         replace=new_symbol.value.is_not_nil();
       }
 
@@ -708,6 +721,9 @@ void linkingt::duplicate_code_symbol(
           old_symbol,
           new_symbol,
           "conflicting function declarations");
+
+        // error logged, continue typechecking other symbols
+        return;
       }
       else
       {
@@ -876,10 +892,15 @@ bool linkingt::adjust_object_type_rec(
       equal_exprt eq(old_size, new_size);
 
       if(!simplify_expr(eq, ns).is_true())
+      {
         link_error(
           info.old_symbol,
           info.new_symbol,
           "conflicting array sizes for variable");
+
+        // error logged, continue typechecking other symbols
+        return true;
+      }
     }
 
     return false;
@@ -958,6 +979,9 @@ void linkingt::duplicate_object_symbol(
         old_symbol,
         new_symbol,
         "conflicting types for variable");
+
+      // error logged, continue typechecking other symbols
+      return;
     }
     else if(set_to_new)
       old_symbol.type=new_symbol.type;
@@ -1022,11 +1046,16 @@ void linkingt::duplicate_non_type_symbol(
   bool is_code_new_symbol=new_symbol.type.id()==ID_code;
 
   if(is_code_old_symbol!=is_code_new_symbol)
+  {
     link_error(
       old_symbol,
       new_symbol,
       "conflicting definition for symbol");
 
+    // error logged, continue typechecking other symbols
+    return;
+  }
+
   if(is_code_old_symbol)
     duplicate_code_symbol(old_symbol, new_symbol);
   else
@@ -1048,11 +1077,16 @@ void linkingt::duplicate_type_symbol(
   assert(new_symbol.is_type);
 
   if(!old_symbol.is_type)
+  {
     link_error(
       old_symbol,
       new_symbol,
       "conflicting definition for symbol");
 
+    // error logged, continue typechecking other symbols
+    return;
+  }
+
   if(old_symbol.type==new_symbol.type)
     return;