[cfe-dev] [Analyzer - UnreachableCodeChecker] Why analyzer suppress the warnings coming from macro?

[Wong Henry via cfe-dev]

Hi all,
I have some questions about UnreachableCodeChecker. It seems that UnreachableCodeChecker suppresses some dead code warnings coming from macros.
Given the below code sippet:
-------------------------------------------------
  1 #include <stdio.h>
  2 #define MACRO(cond)       \
  3     if (cond) { printf("dead code\n"); }   <---- dead code
  4
  5 void foo()
  6 {
  7     MACRO(0)
  8 }
-------------------------------------------------
It is reasonable to suppress the dead code warning in the above code sample. But it is unreasonable to suppress some other dead code warnings.
For example:
-------------------------------------------------
  1 #include <stdio.h>
  2 #define MACRO(cond)       \
  3     if (0) { printf("dead code\n"); }   <---- dead code
  4
  5 void foo()
  6 {
  7     MACRO(0)
  8 }
-------------------------------------------------
No matter what 'cond' is, the 'printf' is always unreachable. So I have the following two questions:
(1) What caused UnreachableCodeChecker to be designed like that?
(2) If I want to make some improvements, what kind of work should I do, for example, only suppress dead code warnings that depend on macro arguments and suppresses common patterns in macros like 'do {...} while (0)'.

Cheers,
Henry Wong
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