ckaestne / TypeChef

Type checking ifdef variability
https://ckaestne.github.io/TypeChef/
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Handling of labled statements broken #21

Open ckaestne opened 11 years ago

ckaestne commented 11 years ago

Parsing of labeled statements is incorrect (our grammar needs fixing)

We parse labels as separate statements. That is a: b: c(); is parsed as three statements: List(LabeledStatement(a), LabeledStatement(b), FunctionCall(c..)). In the ANSI C grammar this is a single statement LabeledStatement(a, LabeledStatement(b, FunctionCall(c..))). In GCC this is again handled differently, closer to our separate statements: the internal tree representation actually creates an internal block where needed.

Here is the original code block (one statement) from uclibc that illustrates the problem:

if (0)
        jin:{
        if ((a = *++haystack) == c)
          goto crest;
          }
        else
          a = *++haystack;

Corresponding grammar: http://www.lysator.liu.se/c/ANSI-C-grammar-y.html and corresponding parser code in GCC: https://github.com/mirrors/gcc/blob/master/gcc/c/c-parser.c#L4457

Fixing the grammar will require follow up fixes in the data flow analysis and simple changes in the type system.

ckaestne commented 11 years ago

will be fixed in fix_goto branch