Use gitattributes to define per-path whitespace rule

The `core.whitespace` configuration variable allows you to define what
`diff` and `apply` should consider whitespace errors for all paths in
the project (See gitlink:git-config[1]).  This attribute gives you finer
control per path.

For example, if you have these in the .gitattributes:

    frotz   whitespace
    nitfol  -whitespace
    xyzzy   whitespace=-trailing

all types of whitespace problems known to git are noticed in path 'frotz'
(i.e. diff shows them in diff.whitespace color, and apply warns about
them), no whitespace problem is noticed in path 'nitfol', and the
default types of whitespace problems except "trailing whitespace" are
noticed for path 'xyzzy'.  A project with mixed Python and C might want
to have:

    *.c    whitespace
    *.py   whitespace=-indent-with-non-tab

in its toplevel .gitattributes file.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index 20cf8ff81..c4bcbb935 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -360,6 +360,37 @@ When left unspecified, the driver itself is used for both
 internal merge and the final merge.
 
 
+Checking whitespace errors
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+`whitespace`
+^^^^^^^^^^^^
+
+The `core.whitespace` configuration variable allows you to define what
+`diff` and `apply` should consider whitespace errors for all paths in
+the project (See gitlink:git-config[1]).  This attribute gives you finer
+control per path.
+
+Set::
+
+	Notice all types of potential whitespace errors known to git.
+
+Unset::
+
+	Do not notice anything as error.
+
+Unspecified::
+
+	Use the value of `core.whitespace` configuration variable to
+	decide what to notice as error.
+
+String::
+
+	Specify a comma separate list of common whitespace problems to
+	notice in the same format as `core.whitespace` configuration
+	variable.
+
+
 EXAMPLE
 -------