gcc.info: Warnings and Errors
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Warning Messages and Error Messages
The GNU compiler can produce two kinds of diagnostics: errors and
warnings. Each kind has a different purpose:
*Errors* report problems that make it impossible to compile your
program. GCC reports errors with the source file name and line
number where the problem is apparent.
*Warnings* report other unusual conditions in your code that *may*
indicate a problem, although compilation can (and does) proceed.
Warning messages also report the source file name and line number,
but include the text `warning:' to distinguish them from error
messages.
Warnings may indicate danger points where you should check to make
sure that your program really does what you intend; or the use of
obsolete features; or the use of nonstandard features of GNU C or C++.
Many warnings are issued only if you ask for them, with one of the `-W'
options (for instance, `-Wall' requests a variety of useful warnings).
GCC always tries to compile your program if possible; it never
gratuitously rejects a program whose meaning is clear merely because
(for instance) it fails to conform to a standard. In some cases,
however, the C and C++ standards specify that certain extensions are
forbidden, and a diagnostic *must* be issued by a conforming compiler.
The `-pedantic' option tells GCC to issue warnings in such cases;
`-pedantic-errors' says to make them errors instead. This does not
mean that *all* non-ANSI constructs get warnings or errors.
*Note Options to Request or Suppress Warnings: Warning Options, for
more detail on these and related command-line options.
Created Wed Sep 1 16:42:21 2004 on bee with info_to_html version 0.9.6.