trace: fix tcg tracing build breakage

[mirror_qemu.git] / CODING_STYLE

diff --git a/CODING_STYLE b/CODING_STYLE
index 4280945ff021d35f54d0a9b8c0214372c8fa8655..2fa0c0b65b6c1315202741193b725b537f2bf2ff 100644 (file)
--- a/CODING_STYLE
+++ b/CODING_STYLE
@@ -9,7 +9,7 @@ patches before submitting.
 Of course, the most important aspect in any coding style is whitespace.
 Crusty old coders who have trouble spotting the glasses on their noses
 can tell the difference between a tab and eight spaces from a distance
-of approximately fifteen parsecs.  Many a flamewar have been fought and
+of approximately fifteen parsecs.  Many a flamewar has been fought and
 lost on this issue.
 
 QEMU indents are four spaces.  Tabs are never used, except in Makefiles
@@ -31,7 +31,11 @@ Do not leave whitespace dangling off the ends of lines.
 
 2. Line width
 
-Lines are 80 characters; not longer.
+Lines should be 80 characters; try not to make them longer.
+
+Sometimes it is hard to do, especially when dealing with QEMU subsystems
+that use long function or symbol names.  Even in that case, do not make
+lines much longer than 80 characters.
 
 Rationale:
  - Some people like to tile their 24" screens with a 6x4 matrix of 80x24
@@ -39,6 +43,8 @@ Rationale:
    let them keep doing it.
  - Code and especially patches is much more readable if limited to a sane
    line length.  Eighty is traditional.
+ - The four-space indentation makes the most common excuse ("But look
+   at all that white space on the left!") moot.
  - It is the QEMU coding style.
 
 3. Naming
@@ -87,7 +93,33 @@ Furthermore, it is the QEMU coding style.
 
 5. Declarations
 
-Mixed declarations (interleaving statements and declarations within blocks)
-are not allowed; declarations should be at the beginning of blocks.  In other
-words, the code should not generate warnings if using GCC's
--Wdeclaration-after-statement option.
+Mixed declarations (interleaving statements and declarations within
+blocks) are generally not allowed; declarations should be at the beginning
+of blocks.
+
+Every now and then, an exception is made for declarations inside a
+#ifdef or #ifndef block: if the code looks nicer, such declarations can
+be placed at the top of the block even if there are statements above.
+On the other hand, however, it's often best to move that #ifdef/#ifndef
+block to a separate function altogether.
+
+6. Conditional statements
+
+When comparing a variable for (in)equality with a constant, list the
+constant on the right, as in:
+
+if (a == 1) {
+    /* Reads like: "If a equals 1" */
+    do_something();
+}
+
+Rationale: Yoda conditions (as in 'if (1 == a)') are awkward to read.
+Besides, good compilers already warn users when '==' is mis-typed as '=',
+even when the constant is on the right.
+
+7. Comment style
+
+We use traditional C-style /* */ comments and avoid // comments.
+
+Rationale: The // form is valid in C99, so this is purely a matter of
+consistency of style. The checkpatch script will warn you about this.