PRB: Editing While Debugging Causes Breakpoint Misalignment

• The integrated debugger included with: Microsoft Visual C++ 32-bit Edition, version 2.0, 2.1, 2.2, 4.0, 5.0

SYMPTOMS

During debugging it is common to find bugs and make minor code changes as you continue debugging. However, editing source code while in the middle of a debugging session may cause new or existing "Break At Location" breakpoints to become misaligned with their corresponding instructions. ("Break At Location" is the default type if the breakpoints are set using the toolbar button in the Visual C++ development environment.)

If, after editing, the source file remains the same in terms of line positions, then breakpoints will appear as expected. However, if the source file changes in terms of line positions, new breakpoint indicators (the red dots) will shift position with respect to their corresponding instruction by the number of lines added or deleted before each breakpoint.

Alternately, the red dot breakpoint indicators for pre-existing breakpoints will follow their corresponding instructions during editing, but after the rebuild warning, the program execution continues and the pre-existing breakpoints are hit, the yellow current instruction pointer will be out of sync with the corresponding instruction by the number of lines added or deleted before each breakpoint.

CAUSE

The debugger does not track line number changes during editing, so it does not update new breakpoint and the current instruction pointer indicators accordingly.

STATUS

This behavior is by design.