erichkeane created this revision.
erichkeane added reviewers: aaron.ballman, jdoerfert, jroelofs.
Herald added a project: LLVM.
This is a rule that seems to have been enforced for the better part of
the decade, so we should document it for new contributors.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D80947
Files:
llvm/docs/CodingStandards.rst
Index: llvm/docs/CodingStandards.rst
===================================================================
--- llvm/docs/CodingStandards.rst
+++ llvm/docs/CodingStandards.rst
@@ -669,15 +669,15 @@
.. code-block:: c++
// Typically there's no reason to copy.
- for (const auto &Val : Container) { observe(Val); }
- for (auto &Val : Container) { Val.change(); }
+ for (const auto &Val : Container) observe(Val);
+ for (auto &Val : Container) Val.change();
// Remove the reference if you really want a new copy.
for (auto Val : Container) { Val.change(); saveSomewhere(Val); }
// Copy pointers, but make it clear that they're pointers.
- for (const auto *Ptr : Container) { observe(*Ptr); }
- for (auto *Ptr : Container) { Ptr->change(); }
+ for (const auto *Ptr : Container) observe(*Ptr);
+ for (auto *Ptr : Container) Ptr->change();
Beware of non-determinism due to ordering of pointers
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -884,7 +884,7 @@
.. code-block:: c++
Value *doSomething(Instruction *I) {
- // Terminators never need 'something' done to them because ...
+ // Terminators never need 'something' done to them because ...
if (I->isTerminator())
return 0;
@@ -896,7 +896,7 @@
// This is really just here for example.
if (!doOtherThing(I))
return 0;
-
+
... some long code ....
}
@@ -1000,7 +1000,7 @@
Type = Context.getsigjmp_bufType();
else
Type = Context.getjmp_bufType();
-
+
if (Type.isNull()) {
Error = Signed ? ASTContext::GE_Missing_sigjmp_buf :
ASTContext::GE_Missing_jmp_buf;
@@ -1010,7 +1010,7 @@
The idea is to reduce indentation and the amount of code you have to keep track
of when reading the code.
-
+
Turn Predicate Loops into Predicate Functions
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -1081,7 +1081,7 @@
* **Variable names** should be nouns (as they represent state). The name should
be camel case, and start with an upper case letter (e.g. ``Leader`` or
``Boats``).
-
+
* **Function names** should be verb phrases (as they represent actions), and
command-like function should be imperative. The name should be camel case,
and start with a lower case letter (e.g. ``openFile()`` or ``isFoo()``).
@@ -1091,7 +1091,7 @@
discriminator for a union, or an indicator of a subclass. When an enum is
used for something like this, it should have a ``Kind`` suffix
(e.g. ``ValueKind``).
-
+
* **Enumerators** (e.g. ``enum { Foo, Bar }``) and **public member variables**
should start with an upper-case letter, just like types. Unless the
enumerators are defined in their own small namespace or inside a class,
@@ -1107,7 +1107,7 @@
MaxSize = 42,
Density = 12
};
-
+
As an exception, classes that mimic STL classes can have member names in STL's
style of lower-case words separated by underscores (e.g. ``begin()``,
``push_back()``, and ``empty()``). Classes that provide multiple
@@ -1360,7 +1360,7 @@
The use of ``#include <iostream>`` in library files is hereby **forbidden**,
because many common implementations transparently inject a `static constructor`_
into every translation unit that includes it.
-
+
Note that using the other stream headers (``<sstream>`` for example) is not
problematic in this regard --- just ``<iostream>``. However, ``raw_ostream``
provides various APIs that are better performing for almost every use than
@@ -1492,7 +1492,7 @@
public:
explicit Grokable() { ... }
virtual ~Grokable() = 0;
-
+
...
};
@@ -1541,8 +1541,8 @@
};
} // end anonymous namespace
- static void runHelper() {
- ...
+ static void runHelper() {
+ ...
}
bool StringSort::operator<(const char *RHS) const {
@@ -1570,6 +1570,33 @@
contrast, when the function is marked static, you don't need to cross-reference
faraway places in the file to tell that the function is local.
+Don't Use Braces on Simple Single-Statement Bodies of if/else/loop Statements
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When writing the body of an if, else, or loop statement omit the braces to avoid
+unnecessary and otherwise meaningless lines of code. Braces should be used however
+in cases where it significantly improves readability, such as when the single
+statement is accompanied by a comment that loses its meaning if hoisted above the if
+or loop statement, or where the single statement is complex enough that it stops being
+clear that it is a single line. Note that comments should only be hoisted for loops and
+'if', and not in 'else if' or 'else', where it would be unclear whether the comment
+belonged to the preceeding condition, or the 'else'.
+
+.. code-block:: c++
+
+ // Omit the braces, since the body is simple and clearly associated with the 'if'.
+ if (isa<FunctionDecl>(D))
+ handleFunctionDecl(D);
+ else if (isa<VarDecl>(D))
+ handleVarDecl(D);
+ else {
+ // In this else case, it is necessary that we explain the situation with this
+ // surprisingly long comment, so it would be unclear without the braces whether
+ // the following statement is in the scope of the 'else'.
+ handleOtherDecl(D);
+ }
+
+
See Also
========
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