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+(This file was generated by makeinfo and splitinfo.gawk.)
+(Released under the old-style GNU documentation license;
+ see sources or other output files for full text.)
+
+9 Coding conventions
+********************
+
+Ideally, building all of TeX Live with '--enable-compiler-warnings=max'
+should produce no (GCC) compiler warnings at all.  In spite of
+considerable efforts into that direction we are still far from that goal
+and there are reasons that we may never fully reach it.  Below are some
+rules about declarations of functions or variables and the use of
+'const'.  These rules should be applied to all parts of the TeX Live
+tree, except some of those maintained independently.
+
+9.1 Declarations and definitions
+================================
+
+C standards
+...........
+
+The TeX Live build system no longer supports pre-ANSI C compilers.  Thus
+all function prototypes and definitions must conform to the ANSI C
+standard (including 'void' in the declaration of C functions with no
+parameters).  On the other hand, TL is built for a wide variety of
+systems, not all of which support the C99 standard.  Therefore using C99
+features should be avoided if that can easily be done.  In particular C
+code must not contain declarations after statements or C++-style
+comments.
+
+   If some C99 (or later) constructs must be used, the module should
+verify that they are available and otherwise provide an alternative.
+For example, the module 'texk/chktex' uses the C99 function 'stpcpy()'
+that may or may not be available on a particular system.  It uses
+'AC_CHECK_DECLS([stpcpy])' in 'configure.ac' to test this, and provides
+the perhaps slightly less efficient alternative
+
+     #if !(defined HAVE_DECL_STPCPY && HAVE_DECL_STPCPY)
+     #static inline char *stpcpy(char *dest, const char *src)
+     {
+       return strcpy(dest, src) + strlen(src);
+     }
+     #endif
+
+in the file 'Utility.h'.
+
+Static functions
+................
+
+Functions used in only one file should be declared 'static'; they
+require no prototype except as forward declaration.
+
+Extern functions
+................
+
+Functions not declared 'static', usually because they are used in
+several files, require an ('extern') prototype in exactly one header
+file, which is included in the file defining the function and in all
+files using that function--this is the only way to guarantee consistency
+between definition and use.  There should be no 'extern' declarations
+sprinkled throughout the C code (with or without comments as to where
+that function is defined).
+
+Variable declarations
+.....................
+
+The declaration of global variables follows analogous rules: they are
+either declared 'static' if used in only one file or declared 'extern'
+in exactly one header and instantiated in exactly one file.
+
+9.2 Const
+=========
+
+The 'const' feature of C is valuable, but easy to mis-use.
+
+Function parameters
+...................
+
+Ideally, a function parameter not modified by the function should be
+declared as 'const'.  This is important in particular for strings
+('char*') because the actual arguments are often string literals.  It is
+perfectly legitimate and safe to use a type 'char*' value for a type
+'const char*' variable (in an assignment, as initializer, as function
+argument, or as return value).  It is equally safe to use a type
+'char**' value for a type 'const char*const*' variable, but not for a
+type 'const char**' variable since that might cause modification of a
+quantity supposed to be constant.
+
+   Getting all 'const' qualifiers right can get quite involved but can
+almost always be done.  There are only a couple notable exceptions: the
+X11 headers are full of declarations that ought to use 'const' but do
+not, and the same is true to some extent for 'libfreetype' (but,
+thankfully, not for 'zlib' nowadays).
+
+What must be avoided with 'const'
+.................................
+
+The GCC compiler warnings "assignment discards qualifiers..." and
+analogous warnings for "initialization", "passing arg", or "return" must
+be strenously avoided in our own code.  The only exception is when they
+are caused by X11 headers or macros or other third party code.
+
+What should be avoided with 'const'
+...................................
+
+A type cast, e.g., from 'const char*' to 'char*' does not solve any
+problems; depending on warning options, it may only hide them.
+Therefore such casts should be avoided whenever possible and otherwise
+must be carefully analyzed to make sure that they cannot cause the
+modification of quantities supposed to be constant.
+