Question

I was looking for a tool that can convert C code expressions for the form:

a = (A) ? B : C;

into the ‘default’ syntax with if/else statements:

if (A)
  a = B
else
  a = C

Does someone know a tool that’s capable to do such a transformation?

I work with GCC 4.4.2 and create a preprocessed file with -E but do not want such structures in it.

Edit:
Following code should be transformed, too:

a = ((A) ? B : C)->b;

Answer 1

Coccinelle can do this quite easily.

Coccinelle is a program matching and
transformation engine which provides
the language SmPL (Semantic Patch
Language) for specifying desired
matches and transformations in C code.
Coccinelle was initially targeted
towards performing collateral
evolutions in Linux. Such evolutions
comprise the changes that are needed
in client code in response to
evolutions in library APIs, and may
include modifications such as renaming
a function, adding a function argument
whose value is somehow
context-dependent, and reorganizing a
data structure. Beyond collateral
evolutions, Coccinelle is successfully
used (by us and others) for finding
and fixing bugs in systems code.

EDIT:
An example of semantic patch:

@@ expression E; constant C; @@
(
  !E & !C
|
- !E & C
+ !(E & C)
)

From the documentation:

The pattern !x&y. An expression of this form is almost always meaningless, because it combines a boolean operator with a bit operator. In particular, if the rightmost bit of y is 0, the result will always be 0. This semantic patch focuses on the case where y is a constant.

You have a good set of examples here.

The mailing list is really active and helpful.