[lldb-mi] Fix expansion of anonymous structures and unions

[evgeny777]

Summary

Suppose we have the following type

struct S {
   union {
       int            i1;
       unsigned u1;
   };
   union {
       int            i2;
       unsigned u2;
   };
};

Current revision makes it impossible to evaluate it using MI, because MI assigns '??' as variable name to each of the unnamed unions after "-var-list-children" command. Also '??' incorrectly goes to 'exp' field which is treated by IDE as a structure field name and is displayed in watch window.

The patch fixes this returning empty string as type name for unnamed union and assigning $N to variable name, where N is the field number in the parent entity.

[abidh]

LGTM. Thanks for doing it. For this case, the output of the lldb-mi looks more sensible then gdb.

test/tools/lldb-mi/variable/TestMiVar.py

def test_lldbmi_var_create_for_stl_types(self):
         self.runCmd("-exec-run")
         self.expect("\^running")
         self.expect("\*stopped,reason=\"breakpoint-hit\"")
 
         # Test for std::string
         self.runCmd("-var-create - * std_string")
         self.expect('\^done,name="var\d+",numchild="[0-9]+",value="\\\\"hello\\\\"",type="std::[\S]*?string",thread-id="1",has_more="0"')
 
+    @lldbmi_test
+    @skipIfWindows #llvm.org/pr24452: Get lldb-mi working on Windows
+    @skipIfFreeBSD # llvm.org/pr22411: Failure presumably due to known thread races
+    @skipIfLinux # llvm.org/pr22841: lldb-mi tests fail on all Linux buildbots
+    def test_lldbmi_var_create_for_unnamed_objects(self):
+        """Test that 'lldb-mi --interpreter' can expand unnamed structures and unions."""
+
+        self.spawnLldbMi(args = None)
+
+        # Load executable
+        self.runCmd("-file-exec-and-symbols %s" % self.myexe)
+        self.expect("\^done")
+
+        # Run to breakpoint
+        line = line_number('main.cpp', '// BP_unnamed_objects_test')
+        self.runCmd("-break-insert main.cpp:%d" % line)
+        self.expect("\^done,bkpt={number=\"1\"")
+        self.runCmd("-exec-run")
+        self.expect("\^running")
+        self.expect("\*stopped,reason=\"breakpoint-hit\"")
+
+        # Evaluate struct_with_unions type and its children
+        self.runCmd("-var-create v0 * swu")
+        self.expect('\^done,name="v0",numchild="2",value="\{\.\.\.\}",type="struct_with_unions",thread-id="1",has_more="0"')
+       
+        self.runCmd("-var-list-children v0")
+        
+        # inspect the first unnamed union
+        self.runCmd("-var-list-children v0.$0")
+        self.runCmd("-var-evaluate-expression v0.$0.u_i")
+        self.expect('\^done,value="1"')
+        
+        # inspect the second unnamed union
+        self.runCmd("-var-list-children v0.$1")
+        self.runCmd("-var-evaluate-expression v0.$1.u1")
+        self.expect('\^done,value="-1"')
+        # inspect unnamed structure
+        self.runCmd("-var-list-children v0.$1.$1")
+        self.runCmd("-var-evaluate-expression v0.$1.$1.s1")
+        self.expect('\^done,value="-1"')
+
 if __name__ == '__main__':
     unittest2.main()

test/tools/lldb-mi/variable/main.cpp

struct pcomplex_type : complex_type
     pcomplex_type(const complex_type &complx_base, const complex_type &complx_member)
         : complex_type(complx_base), complx(complx_member) { }
     complex_type complx;
     static int si;
 };
 
 int pcomplex_type::si;
 
+struct struct_with_unions
+{
+    struct_with_unions(): u_i(1), u1(-1) {}
+    union 
+    {
+        int u_i;
+        int u_j;  
+    };
+    union 
+    {
+        int  u1;
+        struct
+        {
+            short s1;
+            short s2;
+        };
+    };
+};
+
 void
 var_update_test(void)
 {
     long l = 1;
     complex_type complx = { 3, { 3L }, &complx };
     complex_type complx_array[2] = { { 4, { 4L }, &complx_array[1] }, { 5, { 5 }, &complx_array[0] } };
     // BP_var_update_test_init
 

 
 void
 cpp_stl_types_test(void)
 {
     std::string std_string = "hello";
     // BP_cpp_stl_types_test
 }
 
+void
+unnamed_objects_test(void)
+{
+    struct_with_unions swu;
+    // BP_unnamed_objects_test
+}
+
 struct not_str
 {
     not_str(char _c, int _f)
         : c(_c), f(_f) { }
     char c;
     int f;
 };
 

 main(int argc, char const *argv[])
 {
     int a = 10, b = 20;
     s_MyVar = a + b;
     var_update_test();
     var_list_children_test();
     gdb_set_show_print_char_array_as_string_test();
     cpp_stl_types_test();
+    unnamed_objects_test();
     gdb_set_show_print_expand_aggregates();
     gdb_set_show_print_aggregate_field_names();
     return 0; // BP_return
 }

tools/lldb-mi/MICmdCmdVar.cpp

CMICmdCmdVarListChildren::Execute()
     m_bHasMore = nTo < nChildren;
     nTo = std::min(nTo, nChildren);
     m_nChildren = nFrom < nTo ? nTo - nFrom : 0;
     for (MIuint i = nFrom; i < nTo; i++)
     {
         lldb::SBValue member = rValue.GetChildAtIndex(i);
         const CMICmnLLDBUtilSBValue utilValue(member);
         const CMIUtilString strExp = utilValue.GetName();
-        const CMIUtilString name(CMIUtilString::Format("%s.%s", rVarObjName.c_str(), strExp.c_str()));
+        const CMIUtilString name(strExp.empty() ?
+            CMIUtilString::Format("%s.$%u", rVarObjName.c_str(), i) :
+            CMIUtilString::Format("%s.%s", rVarObjName.c_str(), strExp.c_str()));
         const MIuint nChildren = member.GetNumChildren();
         const CMIUtilString strThreadId(CMIUtilString::Format("%u", member.GetThread().GetIndexID()));
 
         // Varobj gets added to CMICmnLLDBDebugSessionInfoVarObj static container of varObjs
         CMICmnLLDBDebugSessionInfoVarObj var(strExp, name, member, rVarObjName);
 
         // MI print "child={name=\"%s\",exp=\"%s\",numchild=\"%d\",value=\"%s\",type=\"%s\",thread-id=\"%u\",has_more=\"%u\"}"
         const CMICmnMIValueConst miValueConst(name);

tools/lldb-mi/MICmnLLDBUtilSBValue.cpp

 // Args:    None.
 // Return:  CMIUtilString   - Name of the variable or "??" for unknown.
 // Throws:  None.
 //--
 CMIUtilString
 CMICmnLLDBUtilSBValue::GetName() const
 {
     const char *pName = m_bValidSBValue ? m_rValue.GetName() : nullptr;
-    const CMIUtilString text((pName != nullptr) ? pName : m_pUnkwn);
+    const CMIUtilString text((pName != nullptr) ? pName : CMIUtilString());
 
     return text;
 }
 
 //++ ------------------------------------------------------------------------------------
 // Details: Retrieve from the LLDB SB Value object the value of the variable described in
 //          text. If the value is invalid (or the SBValue object invalid) then "??" is
 //          returned.