Fix bug in expression display when determining if a pointer should be treated as a string

[paulmaybee]

Summary

Currently if the "first child" of the pointer is a char type then the pointer is displayed as a string. This test succeeds incorrectly when the pointer is to a structured type with a char type as its first field. Fix this by switching the test to retrieve the pointee type and checking that it is a char type.

[ki.stfu]

It looks strangely for me. If structure has the first element of type char then GetChildAtIndex(0) will refer to this element and GetType().GetBasicType() will be char. But if we have a pointer to that structure then I suppose GetChildAtIndex(0) will not be equal to the first element of structure. From my point of view, it should relate to this structure entirely, but not to its first element.

[ki.stfu]

Add add a test case for this please.

[paulmaybee]

Add test case

[ki.stfu]

See my inline comments.

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

70–76

Use clang-format for formatting please.

86

a memory leak. just allocate it on the stack and then use "&nstr"

tools/lldb-mi/MICmnLLDBUtilSBValue.cpp

139–141

Please wrap it into IsPointeeCharType():

if (m_bHandleCharType && IsPointeeCharType())

364

Change to "Static":

// Type:    Static.

404

Add IsPointeeCharType() function after IsFirstChildCharType():

//++ ------------------------------------------------------------------------------------
// Details: Retrieve the flag stating whether pointee object of *this object is a char
//          type or some other type. Returns false if there are not children. Char type
//          can be signed or unsigned.
// Type:    Method.
// Args:    None.          
// Return:  bool    - True = Yes is a char type, false = some other type.
// Throws:  None.
//--
bool
CMICmnLLDBUtilSBValue::IsPointeeCharType(void) const
{
    const MIuint nChildren = m_rValue.GetNumChildren();

    // Is it a basic type
    if (nChildren == 0)
        return false;

    const lldb::BasicType eType = m_rValue.GetType().GetPointeeType().GetBasicType();
    return IsCharBasicType(eType);
}

tools/lldb-mi/MICmnLLDBUtilSBValue.h

57

Add

bool IsPointeeCharType(void) const;

after these lines:

CMIUtilString GetTypeName(void) const;
CMIUtilString GetTypeNameDisplay(void) const;
bool IsCharType(void) const;
bool IsFirstChildCharType(void) const;

60

Move to separate section:

  // Statics:
private:
  static bool IsCharBasicType(lldb::BasicType eType);

[paulmaybee]

Add IsPointeeCharType

[ki.stfu]

Add a section title and go ahead.

tools/lldb-mi/MICmnLLDBUtilSBValue.h

61

Forgot a section title:

  // Statics:
private:
  static bool IsCharBasicType(lldb::BasicType eType);

[paulmaybee]

Added the section title.
If you are ok with this now then can you please check it in?

Thanks.

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

         self.runCmd("-var-create var2 * complx_array")
         self.expect("\^done,name=\"var2\",numchild=\"2\",value=\"\[2\]\",type=\"complex_type \[2\]\",thread-id=\"1\",has_more=\"0\"")
 
+        # Test that a struct with a char first element is not formatted as a string
+        self.runCmd("-var-create - * ps")
+        self.expect("\^done,name=\"var\d+\",numchild=\"2\",value=\"0x[0-9a-f]+\",type=\"not_str \*\",thread-id=\"1\",has_more=\"0\"")
+        
         # Test that -gdb-set can set print expand-aggregates flag
         self.runCmd("-gdb-set print expand-aggregates on")
         self.expect("\^done")

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

     // BP_gdb_set_show_print_char_array_as_string_test
 }
 
+struct not_str
+{
+    char c;
+    int f;
+    not_str(char _c, int _f)
+    : c(_c)
+    , f(_f)
+    {
+    }
+};
+
 void
 gdb_set_show_print_expand_aggregates(void)
 {
     complex_type complx = { 3, { 3L }, &complx };
     complex_type complx_array[2] = { { 4, { 4L }, &complx_array[1] }, { 5, { 5 }, &complx_array[0] } };
+    not_str nstr('a', 0);
+    not_str* ps = &nstr;
 
     // BP_gdb_set_show_print_expand_aggregates
 }

tools/lldb-mi/MICmnLLDBUtilSBValue.h

     CMIUtilString GetTypeNameDisplay(void) const;
     bool IsCharType(void) const;
     bool IsFirstChildCharType(void) const;
+    bool IsPointeeCharType(void) const;
     bool IsIntegerType(void) const;
     bool IsPointerType(void) const;
     bool IsArrayType(void) const;

     CMIUtilString GetSimpleValueCStringPointer(void) const;
     CMIUtilString GetSimpleValueCStringArray(void) const;
     bool GetCompositeValue(const bool vbPrintFieldNames, CMICmnMIValueTuple &vwrMiValueTuple, const MIuint vnDepth = 1) const;
     
+  private:
+    static bool IsCharBasicType(lldb::BasicType eType);
+    
     // Attributes:
   private:
     lldb::SBValue &m_rValue;

tools/lldb-mi/MICmnLLDBUtilSBValue.cpp

     }
     else if (IsPointerType())
     {
-        if (m_bHandleCharType && IsFirstChildCharType())
+        if (m_bHandleCharType && IsPointeeCharType())
         {
             vwrValue = GetSimpleValueCStringPointer();
             return MIstatus::success;

 }
 
 //++ ------------------------------------------------------------------------------------
-// Details: Retrieve the flag stating whether this value object is a char type or some
-//          other type. Char type can be signed or unsigned.
-// Type:    Method.
-// Args:    None.
+// Details: Check that basic type is a char type. Char type can be signed or unsigned.
+// Type:    Static.
+// Args:    eType   - type to check
 // Return:  bool    - True = Yes is a char type, false = some other type.
 // Throws:  None.
 //--
 bool
-CMICmnLLDBUtilSBValue::IsCharType(void) const
+CMICmnLLDBUtilSBValue::IsCharBasicType(lldb::BasicType eType)
 {
-    const lldb::BasicType eType = m_rValue.GetType().GetBasicType();
     switch (eType)
     {
         case lldb::eBasicTypeChar:

 }
 
 //++ ------------------------------------------------------------------------------------
+// Details: Retrieve the flag stating whether this value object is a char type or some
+//          other type. Char type can be signed or unsigned.
+// Type:    Method.
+// Args:    None.
+// Return:  bool    - True = Yes is a char type, false = some other type.
+// Throws:  None.
+//--
+bool
+CMICmnLLDBUtilSBValue::IsCharType(void) const
+{
+    const lldb::BasicType eType = m_rValue.GetType().GetBasicType();
+    return IsCharBasicType(eType);
+}
+
+
+//++ ------------------------------------------------------------------------------------
 // Details: Retrieve the flag stating whether first child value object of *this object is
 //          a char type or some other type. Returns false if there are not children. Char
 //          type can be signed or unsigned.

 }
 
 //++ ------------------------------------------------------------------------------------
+// Details: Retrieve the flag stating whether pointee object of *this object is
+//          a char type or some other type. Returns false if there are not children. Char
+//          type can be signed or unsigned.
+// Type:    Method.
+// Args:    None.
+// Return:  bool    - True = Yes is a char type, false = some other type.
+// Throws:  None.
+//--
+bool
+CMICmnLLDBUtilSBValue::IsPointeeCharType(void) const
+{
+    const MIuint nChildren = m_rValue.GetNumChildren();
+    
+    // Is it a basic type
+    if (nChildren == 0)
+        return false;
+    
+    const lldb::BasicType eType = m_rValue.GetType().GetPointeeType().GetBasicType();
+    return IsCharBasicType(eType);
+}
+
+//++ ------------------------------------------------------------------------------------
 // Details: Retrieve the flag stating whether this value object is a integer type or some
 //          other type. Char type can be signed or unsigned and short or long/very long.
 // Type:    Method.