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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;
labels need a statement following them. several of our test files were actually incorrect and are rejected by gcc
corresponding changes in CFG are still pending
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 statementLabeledStatement(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:
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.
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