Thread (43 messages) 43 messages, 3 authors, 2021-08-25

Re: [PATCH v2] Documentation: checkpatch: Add TRAILING_SEMICOLON message

From: Dwaipayan Ray <dwaipayanray1@gmail.com>
Date: 2021-08-05 13:49:29

On Wed, Aug 4, 2021 at 2:50 AM Utkarsh Verma [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Add a new message type TRAILING_SEMICOLON for the macro definitions
that conclude with a semicolon.

Suggested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Utkarsh Verma <redacted>
---
 Documentation/dev-tools/checkpatch.rst | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
index f0956e9ea..f2ef998ba 100644
--- a/Documentation/dev-tools/checkpatch.rst
+++ b/Documentation/dev-tools/checkpatch.rst
@@ -845,6 +845,27 @@ Macros, Attributes and Symbols
     Use the `fallthrough;` pseudo keyword instead of
     `/* fallthrough */` like comments.

+  **TRAILING_SEMICOLON**
+    Macro definition should not conclude with a semicolon. The macro
+    invocation should be consistent with the function call. So the macro
+    invocation must conclude with a semicolon. Suppose if a macro MAC is
+    defined::
Maybe:

Macro definition should not end with a semicolon. The macro
invocation style should be consistent with function calls.
This can prevent any unexpected code paths.
+      #define MAC do_something;
+
+    If this macro is used within a if else statement, like::
+
+      if (some_condition)
+              MAC;
+      else
+              do_something;
+
+    Then there would be a compilation error, because when the macro is
+    expanded there are two trailing semicolons, so the else branch gets
+    orphaned.
+
+    See: https://lore.kernel.org/lkml/1399671106.2912.21.camel@joe-AO725/ (local)
+
   **WEAK_DECLARATION**
     Using weak declarations like __attribute__((weak)) or __weak
     can have unintended link defects.  Avoid using them.
--
2.17.1
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