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Annotation of src/usr.bin/xlint/README, Revision 1.2

1.1       cloder      1: lint is divided into 3 separate programs: lint, lint1, and
                      2: lint2 (the latter two programs reside in /usr/libexec).
                      3:
                      4: lint calls /usr/libexec/cpp to preprocess the program, then passes
                      5: the output to lint1, which does most of the work. lint1 then outputs
                      6: a .ln file, which is parsed by lint2 to do more holistic checks. all
                      7: of this is driven by /usr/bin/lint, which is like a wrapper program.
                      8:
                      9: lint1 implements its own C parser.  it is incapable of parsing some
                     10: weird gcc things, such as __attribute__ and so on. OpenBSD's source
                     11: tree already does a good job of removing gcc'isms when parsers other
                     12: than gcc are detected.
                     13:
                     14: lint1 keeps a symbol table for the current context, which always
                     15: includes global symbols for the current translation unit, as well as
                     16: locals (inside a function definition). When it parses a function
                     17: definition, it pushes a symbol table context onto the stack, and
1.2     ! jmc        18: then pops it off when the function definition ends.
1.1       cloder     19:
                     20: lint1 does the vast majority of its checks one expression at a time.
                     21: It uses the symbol table (which contains types of symbols) and almost
                     22: nothing else when doing type conversions. All of the checks happen at
                     23: parse time. lint1 does not really build an abstract syntax tree (AST)
                     24: to represent the entire program; it only keeps track of the symbols
                     25: in the current context, and some minimal information about the types
                     26: of enclosing control blocks (loops, switch statements, etc). When lint1
                     27: is finished parsing an expression, you will not see any more warnings
                     28: regarding that expression.
                     29:
1.2     ! jmc        30: $OpenBSD: README,v 1.1 2006/04/26 16:33:38 cloder Exp $