diff options
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/cpp.texi | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/gcc/doc/cpp.texi b/gcc/doc/cpp.texi index 74da087..3087e35 100644 --- a/gcc/doc/cpp.texi +++ b/gcc/doc/cpp.texi @@ -3087,6 +3087,13 @@ input. Subsequent lines are counted from @var{linenum}. effect. In addition, @var{filename} is a string constant. The following line and all subsequent lines are reported to come from the file it specifies, until something else happens to change that. +@var{filename} is interpreted according to the normal rules for a string +constant: backslash escapes are interpreted. This is different from +@samp{#include}. + +Previous versions of GNU CPP did not interpret escapes in @samp{#line}; +we have changed it because the standard requires they be interpreted, +and most other compilers do. @item #line @var{anything else} @var{anything else} is checked for macro calls, which are expanded. @@ -3304,7 +3311,8 @@ of the form These are called @dfn{linemarkers}. They are inserted as needed into the output (but never within a string or character constant). They mean that the following line originated in file @var{filename} at line -@var{linenum}. +@var{linenum}. @var{filename} will never contain any non-printing +characters; they are replaced with octal escape sequences. After the file name comes zero or more flags, which are @samp{1}, @samp{2}, @samp{3}, or @samp{4}. If there are multiple flags, spaces @@ -3868,6 +3876,17 @@ The @samp{#line} directive used to change GCC's notion of the a double-quoted header file name. In 3.0 and later, it does not. @xref{Line Control}, for further explanation. +@item Syntax of @samp{#line} + +In GCC 2.95 and previous, the string constant argument to @samp{#line} +was treated the same way as the argument to @samp{#include}: backslash +escapes were not honored, and the string ended at the second @samp{"}. +This is not compliant with the C standard. In GCC 3.0, an attempt was +made to correct the behavior, so that the string was treated as a real +string constant, but it turned out to be buggy. In 3.1, the bugs have +been fixed. (We are not fixing the bugs in 3.0 because they affect +relatively few people and the fix is quite invasive.) + @end itemize @node Invocation |