A tcng configuration file can contain instructions that affect the overall processing of the file. These instructions can appear wherever variables or fields are allowed. Unlike variables and fields, they always affect the global state of the processor (tcc).
Currently, one such construct is defined: warnings can be enabled or disabled using the warn construct, which consists of the keyword warn, followed by a comma-separated list of warning switch names, like used with the -W option, see section 5.1.1.
corresponds to an invocation of tcc with -Wnounused -Wtruncate
Unrecognized warning switches yield a warning. Warning switch names must be string constants, and cannot be string expressions.
Implementation note: warning switches on the command line take precedence over warning switches in the configuration file.