Error with casted ternary statements

ID0002131: This issue was created automatically from Mantis Issue 2131. Further discussion may take place here.

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Id	Project	Category	View	Due Date	Updated
ID0002131	Frama-C	Kernel	public	2015-06-04	2016-01-26

Reporter	Ian	Assigned To	yakobowski	Resolution	fixed
Priority	normal	Severity	minor	Reproducibility	always
Platform	-	OS	Ubuntu	OS Version	-
Product Version	Frama-C Sodium	Target Version	-	Fixed in Version	Frama-C Magnesium

Description :

The following is a simplified version from an situation where macros created a statement (which had side effects, unlike this example).

1 void main() { 2 int p=0, i=0, j=0; 3 // (char)( p ? i : j ); // [kernel] user error: cannot cast from void to char 4 ( p ? i : j ); 5 }

When line three is uncommented, frama-c fails with the error noted. Inspecting the normalized version reveals a potential problem (line 3 is commented out).

frama-c void_cast.c -then -print [kernel] Parsing FRAMAC_SHARE/libc/__fc_builtin_for_normalization.i (no preprocessing) [kernel] Parsing void_cast.c (with preprocessing) /* Generated by Frama-C */ void main(void) { int p; int i; int j; p = 0; i = 0; j = 0; if (p) { if (i) ; } else if (j) ; return; }

As seen above, line 4 is normalized to if (p) { if (i) ; } else if (j) ;

Which has two potential problems. First, it is unclear why ‘i' and ‘j’ are wrapped in conditionals. Second, this structure may result in the ‘if’ statement being casted, instead of ‘i' or ‘j’, ultimately producing the observed error.

Running just the gcc preprocessor on the initial source file does not cause these transformations.

gcc -E void_cast.c

1 "void_cast.c"

1 ""

1 ""

1 "void_cast.c"

void main() { int p=0, i=0, j=0; (char)( p ? i : j ); ( p ? i : j ); }

Interestingly, adding an assignment produces a reasonable transformation. The program:

void main() { int p=0, i=0, j=0; char c = (char)( p ? i : j ); }

Is normalized to:

void main(void) { int p; int i; int j; char c; int tmp; p = 0; i = 0; j = 0; if (p) tmp = i; else tmp = j; c = (char)tmp; return; }

Steps To Reproduce :

Create file void_cast.c: void main() { int p=0, i=0, j=0; (char)( p ? i : j ); }

Run frama-c:

frama-c void_cast.c [kernel] Parsing FRAMAC_SHARE/libc/__fc_builtin_for_normalization.i (no preprocessing) [kernel] Parsing void_cast.c (with preprocessing) void_cast.c:3:[kernel] user error: cannot cast from void to char [kernel] user error: stopping on file "void_cast.c" that has errors. Add '-kernel-msg-key pp' for preprocessing command. [kernel] Frama-C aborted: invalid user input.

But expected frama-c to succeed since the program is accepted by gcc.