[Linux-kernel-mentees] [PATCH v5 0/3] cocci: Align the C AST and Cocci AST for pointer

[Linux-kernel-mentees] [PATCH v5 0/3] cocci: Align the C AST and Cocci AST for pointer

[Jaskaran Singh]

This series is to address the type matching problem in Coccinelle.

Patch 1/3 is for aligning the C and Cocci AST so that
pointer to const pointer and its variants can be matched.

Patch 2/3 reflects the pretty printing changes made in 
1/3 in the ptrconstptr test case. A space is added between
the * and const.

Patch 3/3 consists of a test case for matching a pointer to
const pointer and its variants.

Changes in v5:
--------------
- Remove unnecessary parantheses and return of unit in Patch 1/3.
- Have the test case in Patch 3/3 conform more closely with the
  Linux kernel coding style.

Changes in v4:
--------------
- Fix coding style w/r/t placement of comment with List.iter and
  the qualifier printing function.

Changes in v3:
--------------
- Add a space between the * and qualifier in Patch 1/3.
- Add Patch 2/3 to add a space between * and const in the test
  case ptrconstptr.

Changes in v2:
--------------
- Change body and subject of Patch 2/2 as per suggestion of Markus
  Elfring.

[PATCH v5 1/3] parsing_c: Align C AST and Cocci AST for pointer
[PATCH v5 2/3] tests: Add space between * and const in
[PATCH v5 3/3] tests: Add test case to match const pointer variants

 parsing_c/parser_c.mly      |    4 ++--
 parsing_c/pretty_print_c.ml |   15 ++++++++++-----
 tests/constptr.c            |    7 +++++++
 tests/constptr.cocci        |   19 +++++++++++++++++++
 tests/constptr.res          |    7 +++++++
 tests/ptrconstptr.res       |    2 +-
 6 files changed, 46 insertions(+), 8 deletions(-)

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[Linux-kernel-mentees] [PATCH v5 1/3] parsing_c: Align C AST and Cocci AST for pointer

[Jaskaran Singh]

For a pointer, the C parser constructed an AST dissimilar from that
of the Cocci AST. This caused failures in matching with certain
pointer types. For example, for the following case:

char *1 const *2 id;

The C AST constructed would be:
const Pointer1 -> Pointer2 -> char

The Cocci AST constructed would be:
Pointer2 -> const Pointer1 -> char

Change the pointer rule in the C parser so that an AST similar to the
Cocci AST is constructed.

Make necessary changes in the C pretty printer so that the pointer type
is printed correctly.

Signed-off-by: Jaskaran Singh <jaskaransingh7654321@gmail.com>
---
 parsing_c/parser_c.mly      |  4 ++--
 parsing_c/pretty_print_c.ml | 15 ++++++++++-----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/parsing_c/parser_c.mly b/parsing_c/parser_c.mly
index 8d7b761e..4c74f15a 100644
--- a/parsing_c/parser_c.mly
+++ b/parsing_c/parser_c.mly
@@ -1333,14 +1333,14 @@ pointer:
  | tmul                   { (Ast_c.noattr,fun x -> mk_ty (Pointer x) [$1]) }
  | tmul pointer
      { let (attr,ptr) = $2 in
-       (attr,fun x -> mk_ty (Pointer (ptr x)) [$1]) }
+       (attr,fun x -> ptr (mk_ty (Pointer x) [$1])) }
  | tmul type_qualif_list
      { let (attr,tq) = $2 in
        (attr,fun x -> (tq.qualifD, mk_tybis (Pointer x) [$1]))}
  | tmul type_qualif_list pointer
      { let (attr1,tq) = $2 in
        let (attr2,ptr) = $3 in
-       (attr1@attr2,fun x -> (tq.qualifD, mk_tybis (Pointer (ptr x)) [$1])) }
+       (attr1@attr2,fun x -> ptr (tq.qualifD, mk_tybis (Pointer x) [$1])) }
 
 tmul:
    TMul { $1 }
diff --git a/parsing_c/pretty_print_c.ml b/parsing_c/pretty_print_c.ml
index a2e35588..f4821d5c 100644
--- a/parsing_c/pretty_print_c.ml
+++ b/parsing_c/pretty_print_c.ml
@@ -804,11 +804,14 @@ and pp_string_format (e,ii) =
              (FunctionType (return=void, params=int i) *)
           (*WRONG I THINK, use left & right function *)
           (* bug: pp_type_with_ident_rest None t;      print_ident ident *)
+          pp_type_left t;
           pr_elem i;
-          iiqu +> List.iter pr_elem; (* le const est forcement apres le '*' *)
+          iiqu +>
+          List.iter (* le const est forcement apres le '*' *)
+            (function x -> pr_space(); pr_elem x);
           if iiqu <> [] || get_comments_after i <> []
           then pr_space();
-          pp_type_with_ident_rest ident t attrs Ast_c.noattr;
+          print_ident ident
 
       (* ugly special case ... todo? maybe sufficient in practice *)
       | (ParenType ttop, [i1;i2]) ->
@@ -885,11 +888,13 @@ and pp_string_format (e,ii) =
       match ty, iity with
 	(NoType,_) -> failwith "pp_type_left: unexpected NoType"
       | (Pointer t, [i]) ->
+          pp_type_left t;
           pr_elem i;
-          iiqu +> List.iter pr_elem; (* le const est forcement apres le '*' *)
+          iiqu +>
+          List.iter (* le const est forcement apres le '*' *)
+            (function x -> pr_space(); pr_elem x);
           if iiqu <> [] || get_comments_after i <> []
-          then pr_space();
-          pp_type_left t
+          then pr_space()
 
       | (Array (eopt, t), [i1;i2]) -> pp_type_left t
       | (FunctionType (returnt, paramst), [i1;i2]) -> pp_type_left returnt
-- 
2.21.1

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[Linux-kernel-mentees] [PATCH v5 2/3] tests: Add space between * and const in ptrconstptr.res

[Jaskaran Singh]

A space is now added between the * and qualifier. Reflect this
change in the ptrconstptr test case.

Signed-off-by: Jaskaran Singh <jaskaransingh7654321@gmail.com>
---
 tests/ptrconstptr.res | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/ptrconstptr.res b/tests/ptrconstptr.res
index f5b2210c..1d0c3c1d 100644
--- a/tests/ptrconstptr.res
+++ b/tests/ptrconstptr.res
@@ -1,3 +1,3 @@
 void main() {
-	const char *const *y;
+	const char * const *y;
 }
-- 
2.21.1

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[Linux-kernel-mentees] [PATCH v5 3/3] tests: Add test case to match const pointer variants

[Jaskaran Singh]

Pointer to const pointer and its variants would not match previously.
Add a test case for matching these types.

Signed-off-by: Jaskaran Singh <jaskaransingh7654321@gmail.com>
---
 tests/constptr.c     |  7 +++++++
 tests/constptr.cocci | 19 +++++++++++++++++++
 tests/constptr.res   |  7 +++++++
 3 files changed, 33 insertions(+)
 create mode 100644 tests/constptr.c
 create mode 100644 tests/constptr.cocci
 create mode 100644 tests/constptr.res

diff --git a/tests/constptr.c b/tests/constptr.c
new file mode 100644
index 00000000..49f4af65
--- /dev/null
+++ b/tests/constptr.c
@@ -0,0 +1,7 @@
+int main()
+{
+	const char * const *id;
+	const char ** const *id;
+	const char * const **id;
+	const char * const id;
+}
diff --git a/tests/constptr.cocci b/tests/constptr.cocci
new file mode 100644
index 00000000..29f0aa96
--- /dev/null
+++ b/tests/constptr.cocci
@@ -0,0 +1,19 @@
+@ r0 @
+identifier id;
+@@
+const char * const *
+- id
++ id1
+;
+const char * * const *
+- id
++ id2
+;
+const char * const * *
+- id
++ id3
+;
+const char * const
+- id
++ id4
+;
diff --git a/tests/constptr.res b/tests/constptr.res
new file mode 100644
index 00000000..62fe2513
--- /dev/null
+++ b/tests/constptr.res
@@ -0,0 +1,7 @@
+int main()
+{
+	const char * const *id1;
+	const char ** const *id2;
+	const char * const **id3;
+	const char * const id4;
+}
-- 
2.21.1

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Re: [Linux-kernel-mentees] [PATCH v5 0/3] cocci: Align the C AST and Cocci AST for pointer

[Julia Lawall]

On Tue, 11 Feb 2020, Jaskaran Singh wrote:

> This series is to address the type matching problem in Coccinelle.
>
> Patch 1/3 is for aligning the C and Cocci AST so that
> pointer to const pointer and its variants can be matched.
>
> Patch 2/3 reflects the pretty printing changes made in
> 1/3 in the ptrconstptr test case. A space is added between
> the * and const.
>
> Patch 3/3 consists of a test case for matching a pointer to
> const pointer and its variants.

All applied, thanks.

julia

>
> Changes in v5:
> --------------
> - Remove unnecessary parantheses and return of unit in Patch 1/3.
> - Have the test case in Patch 3/3 conform more closely with the
>   Linux kernel coding style.
>
> Changes in v4:
> --------------
> - Fix coding style w/r/t placement of comment with List.iter and
>   the qualifier printing function.
>
> Changes in v3:
> --------------
> - Add a space between the * and qualifier in Patch 1/3.
> - Add Patch 2/3 to add a space between * and const in the test
>   case ptrconstptr.
>
> Changes in v2:
> --------------
> - Change body and subject of Patch 2/2 as per suggestion of Markus
>   Elfring.
>
> [PATCH v5 1/3] parsing_c: Align C AST and Cocci AST for pointer
> [PATCH v5 2/3] tests: Add space between * and const in
> [PATCH v5 3/3] tests: Add test case to match const pointer variants
>
>  parsing_c/parser_c.mly      |    4 ++--
>  parsing_c/pretty_print_c.ml |   15 ++++++++++-----
>  tests/constptr.c            |    7 +++++++
>  tests/constptr.cocci        |   19 +++++++++++++++++++
>  tests/constptr.res          |    7 +++++++
>  tests/ptrconstptr.res       |    2 +-
>  6 files changed, 46 insertions(+), 8 deletions(-)
>
>
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