gcc/ChangeLog:
* doc/extend.texi (Array Parameters): New node.
Signed-off-by: Alejandro Colomar <[email protected]>
---
gcc/doc/extend.texi | 57 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index b4879b3d82ff..d4905af4ba5f 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -604,6 +604,7 @@ GCC supports several extensions relating to array, union,
and struct types,
including extensions for aggregate initializers for objects of these types.
@menu
+* Array Parameters:: Function parameters declared with array type.
* Variable Length:: Arrays whose length is computed at run time.
* Zero Length:: Zero-length arrays.
* Empty Structures:: Structures with no members.
@@ -618,6 +619,62 @@ including extensions for aggregate initializers for
objects of these types.
* Designated Inits:: Labeling elements of initializers.
@end menu
+@node Array Parameters
+@subsection Array Parameters
+@cindex array parameters
+
+Array parameters are adjusted to pointers.
+
+ISO C ignores the length of array parameters.
+However,
+GCC extends the language so that
+the length of array parameters is meaningful.
+
+For a function declared as
+
+@smallexample
+void f (int n, int a[n]);
+@end smallexample
+
+A caller must provide a pointer to at least @code{n} elements
+or a null pointer.
+
+The function must not access more than @code{n} elements,
+if it is a valid pointer.
+
+Type compatibility rules are also extended
+to take this length into account.
+For the purpose of compatibility,
+a first-level pointer and an array of unspecified length
+are considered equivalent.
+
+As an example,
+the following pairs of declarations are compatible:
+
+@smallexample
+void f (int n, int a[n]);
+void f (int n, int a[*]);
+
+void g (int a[2]);
+void g (int a[*]);
+
+void h (int a[2]);
+void h (int *a);
+@end smallexample
+
+But the following pairs are incompatible:
+
+@smallexample
+void i (int n, int a[n]);
+void i (int n, int a[2]);
+
+void j (int n, int a[n]);
+void j (int n, int a[n + 1]);
+@end smallexample
+
+Violations of these rules are diagnosed when possible,
+as part of @code{-Warray-parameter=}.
+
@node Variable Length
@subsection Arrays of Variable Length
@cindex variable-length arrays
--
2.51.0
