Re: [PATCH] userdiff: Add a builtin pattern for dts files

[Stephen Boyd <sboyd@kernel.org>]

Quoting Alban Gruin (2019-01-13 13:26:21)
> Hi Stephen,
> 
> thank you for your patch.  I left a few comments below.
> 
> Le 11/01/2019 à 22:51, Stephen Boyd a écrit :
> > diff --git a/userdiff.c b/userdiff.c
> > index 97007abe5b16..2bc964e11089 100644
> > --- a/userdiff.c
> > +++ b/userdiff.c
> > @@ -23,6 +23,15 @@ IPATTERN("ada",
> >        "[a-zA-Z][a-zA-Z0-9_]*"
> >        "|[-+]?[0-9][0-9#_.aAbBcCdDeEfF]*([eE][+-]?[0-9_]+)?"
> >        "|=>|\\.\\.|\\*\\*|:=|/=|>=|<=|<<|>>|<>"),
> > +PATTERNS("dts",
> > +      /* Node name (with optional label and unit address) */
> > +      "^[ \t]*((([a-zA-Z_][a-zA-Z0-9_]*: )?[a-zA-Z][a-zA-Z0-9,._+-]*(@[a-zA-Z0-9,._+-]+)?"
> 
> From the spec, label and node names “shall be [between] 1 to 31
> characters in length”.  It’s not enforced here, and I guess it’s not
> really git’s job to check for this kind of rule.  Others may disagree
> with me, though.
> 
> Should labels end with exactly one space after the colon, or can there
> be more, or none at all?

There can be any number of spaces after the colon. I can fix the regex
here to accept any amount of whitespace after the colon.

> 
> > +      /* Reference */
> > +      "|&[a-zA-Z_][a-zA-Z0-9_]*[ \t]*)[ \t]*\\{)[ \t]*$",
> 
> It’s not specified in the spec, but these lines must end with a curly
> brace?  

That isn't common but it is supported. I can change the regex to look
for a line that ends in '{' or something that isn't ';' with anything
after the node name?

> What if there is a comment after the curly brace?

There can be a comment after the curly brace or before the curly brace.
The spec allows C style /* */ type comments, in addition to C++ style //
comments. I've never really seen that happen in practice though so it's
not very common. Grepping the linux sources shows two hits:

arch/arm/boot/dts/lpc3250-ea3250.dts:&ohci /* &usbd */ {
arch/arm/boot/dts/lpc3250-phy3250.dts:&ohci /* &usbd */ {

> 
> This pattern does not match the root node, but I guess it’s not
> important as most of the interesting stuff in a dts is not directly in it.

Agreed.

> 
> > +      /* -- */
> > +      /* Property names and math operators */
> > +      "[a-zA-Z0-9,._+?#-]+"
> > +      "|[-+*/%&^|!~]"),
> 
> There is a `%' operator here and in your tests, but it’s not mentioned
> in the spec if I’m not mistaken.  Does it actually exists?

The compiler doesn't seem to complain when it's used. I can send a patch
to update the spec for this rather esoteric feature. I can also include
more tests and support for the boolean relational operators which also
seem to be supported but probably never used.