[RFC v3] coccinelle: add style check for assignment in if

[Kris Borer]

Add a semantic patch for fixing some cases of checkpatch.pl error:

ERROR: do not use assignment in if condition

Signed-off-by: Kris Borer <kborer@xxxxxxxxx>
---
Differences from Julia's version:
 - removed some disjuction variations that led to improper transformations
 - fixed header format
 - added and updated comments
 - reformatted some rules

 scripts/coccinelle/style/assignment_in_if.cocci | 140 ++++++++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100644 scripts/coccinelle/style/assignment_in_if.cocci

diff --git a/scripts/coccinelle/style/assignment_in_if.cocci b/scripts/coccinelle/style/assignment_in_if.cocci
new file mode 100644
index 0000000..57f692d
--- /dev/null
+++ b/scripts/coccinelle/style/assignment_in_if.cocci
@@ -0,0 +1,140 @@
+/// move assignments out of if conditions
+///
+//# This script is designed to correct code where assignments exist in if
+//# conditions. It is only capable of handling a subset of such problems.
+//# Ideally it would handle all checkpatch errors of the following type:
+//#	ERROR: do not use assignment in if condition
+//#
+//# For example:
+//#	if(result = myfun())
+//#
+//# would become:
+//#	result = myfun();
+//#	if(result)
+//
+// Confidence: Moderate
+// Copyright: (C) 2015 Kris Borer.  GPLv2.
+// URL: http://coccinelle.lip6.fr/
+// Comments:
+// Options: --no-includes --include-headers
+
+virtual patch
+
+
+// if ( (ret = call()) )
+// if ( (ret = call()) < 0 )
+@if1@
+expression i;
+expression E, E2;
+statement S1, S2;
+binary operator b;
+@@
+
++ i = E;
+  if (
+(
+- (i = E)
++ i
+|
+- (i = E)
++ i
+  b ...
+|
+- (i = E),
+  E2
+)
+  ) S1 else S2
+
+
+// if ( ptr->fun && (ret = ptr->fun()) )
+@if2@
+expression i2;
+expression E1, E2;
+@@
+
++ if( E1 ) {
++       i2 = E2;
++       if (i2) {
+- if( E1 && (i2 = E2) ) {
+  ...
+- }
++       }
++ }
+
+
+// if ( ptr->fun && (ret = ptr->fun()) < 0 )
+@if3@
+expression i2;
+expression E1, E2;
+constant c;
+binary operator b;
+@@
+
++ if( E1 ) {
++       i2 = E2;
++       if (i2 b c) {
+- if( E1 && ((i2 = E2) b c) ) {
+  ...
+- }
++       }
++ }
+
+
+// if ( (ret = call()) && ret != -1 )
+// if ( (ret = call()) < 0 && ret != -1 )
+@if4@
+expression i;
+expression E, E2;
+statement S1, S2;
+binary operator b;
+@@
+
++ i = E;
+  if (
+(
+- (i = E)
++ i
+|
+  (
+- (i = E)
++ i
+  b
+  ...)
+)
+  && E2 ) S1 else S2
+
+
+// if ( (ret = call()) && ret != -1 && ret != -2 )
+// if ( (ret = call()) < 0 && ret != -1 && ret != -2 )
+@if5@
+expression i;
+expression E, E2, E3;
+statement S1, S2;
+binary operator b;
+@@
+
++ i = E;
+  if (
+(
+- (i = E)
++ i
+|
+  (
+- (i = E)
++ i
+  b
+  ...)
+)
+  && E2 && E3 ) S1 else S2
+
+
+// warn about any assignments that were missed
+@if6@
+expression i,e;
+statement S1,S2;
+@@
+
+  if (<+...
+- i = e
++ BAD
+  ...+>) S1 else S2
-- 
1.9.1

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