I'm looking for the C grammar in GCC source code, more specifically for the grammar in the yacc/bison form.
Found the C grammar in Yacc specification in the GCC version 3.3 in the file "c-parse.y"
You will not find a C grammar yacc/bison file within the current GCC source code. It was done in the past, before the egcs fork stuff. I cannot give you the exact version and location, but i can tell you that it should be in the 2.x release
The current version of GCC has its own C parser
GCC of version 4.3 did not contain explicitly written C grammar. Parsing and semantical analysis were performed simultaneously, without presenting syntax tree as a separate data structure.
Information source: I read the GCC source code.
GCC's g++ switched from a yacc (bison) based parser years ago (probably at least 5 years). They started using a recursive decent parser because C++ is difficult in yacc.
After using this parser in for C++ for several years they switched C to parsing using recursive decent as well.
You will have to go back several versions to locate the grammar in bison format, but it is out there. You should try google's code search with
gcc yyparse
Update: Google Code Search Shutdown in 2012
http://en.wikipedia.org/wiki/Google_Code_Search
Old: http://yaxx.googlecode.com/svn/branches/yaxx-proc/gcc-3.4.0/gcc/c-parse.y
to find a version of gcc that has it and then you should be able to find the yacc/bison source file in there. It will be old, though.
GCC doesn't use a generated parser; its parser is a hand-written recursive-descent parser.
Also ANSI C Yacc grammar
The C grammar can be found in comments in c-parser.c file in GCC sources. It is not a yacc/bison though as it has already been said.
来源：https://stackoverflow.com/questions/2721071/c-grammar-in-gcc-source-code