@@ -54,21 +54,34 @@ a work-in-progress.</p>
<!-- .................................................................. -->
<h2 id="general">General Improvements</h2>
-<p>The following built-in functions have been introduced.</p>
<ul>
- <li><code>__builtin_roundeven</code> for the corresponding function from
- ISO/IEC TS 18661.
+ <li>New built-in functions:
+ <ul>
+ <li>The
+ <a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/cpp/_005f_005fhas_005fbuiltin.html#g_t_005f_005fhas_005fbuiltin"><code>__has_builtin</code></a>
+ built-in preprocessor operator can be used to query support
+ for built-in functions provided by GCC and other compilers
+ that support it.
+ </li>
+ <li><code>__builtin_roundeven</code> for the corresponding function from
+ ISO/IEC TS 18661.
+ </li>
+ </ul>
</li>
<li>
- A new option, <a href="https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-fno-allocation-dce"><code>-fallocation-dce</code></a>
- has been added. The option removes unneeded pairs of <code>new</code>
- and <code>delete</code> operators.
+ New command-line options:
+ <ul>
+ <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Optimize-Options.html#index-fno-allocation-dce"><code>-fallocation-dce</code></a>
+ removes unneeded pairs of <code>new</code> and <code>delete</code>
+ operators.
+ </li>
+ </ul>
</li>
<li>
Profile driven optimization improvements:
<ul>
<li>
- Using <a href="https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-fprofile-values"><code>-fprofile-values</code></a>,
+ Using <a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Optimize-Options.html#index-fprofile-values"><code>-fprofile-values</code></a>,
an instrumented binary can track multiple
values (up to 4) for e.g. indirect calls and provide more precise profile information.
</li>
@@ -78,7 +91,7 @@ a work-in-progress.</p>
Link-time optimization improvements:
<ul>
<li>
- A new binary <a href="https://gcc.gnu.org/onlinedocs/gcc/lto-dump.html"><code>lto-dump</code></a>
+ A new binary <a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/lto-dump.html"><code>lto-dump</code></a>
has been added. The program can dump various
information about a LTO bytecode object file.
</li>
@@ -102,7 +115,63 @@ a work-in-progress.</p>
<!-- <h3 id="brig">BRIG (HSAIL)</h3> -->
-<!-- <h3 id="c-family">C family</h3> -->
+<h3 id="c-family">C family</h3>
+<ul>
+ <li>New attributes:
+ <ul>
+ <li>
+ The <code>access</code> function and type attribute has been added
+ to describe how a function accesses objects passed to it by pointer
+ or reference, and to associate such arguments with integer arguments
+ denoting the objects' sizes. The attribute is used to enable
+ the detection of invalid accesses by user-defined functions, such
+ as those diagnosed by <code>-Wstringop-overflow</code>.
+ </li>
+ </ul>
+ </li>
+ <li>New warnings:
+ <ul>
+ <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wstring-compare"><code>-Wstring-compare</code></a>, enabled
+ by <code>-Wextra</code>, warns about equality and inequality
+ expressions between zero and the result of a call to either
+ <code>strcmp</code> and <code>strncmp</code> that evaluate to
+ a constant as a result of the length of one argument being greater
+ than the size of the array pointed to by the other.
+ </li>
+ <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wzero-length-bounds"><code>-Wzero-length-bounds</code></a>,
+ enabled by <code>-Warray-bounds</code>, warns about accesses to
+ elements of zero-length arrays that might overlap other members
+ of the same object.
+ </li>
+ </ul>
+ </li>
+ <li>Enhancements to existing warnings:
+ <ul>
+ <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Warray-bounds"><code>-Warray-bounds</code></a>
+ detects more out-of-bounds accesses to member arrays as well as
+ accesses to elements of zero-length arrays.
+ </li>
+ <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wformat-overflow"><code>-Wformat-overflow</code></a>
+ makes full use of string length information computed by
+ the <code>strlen</code> optimization pass.
+ </li>
+ <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wrestrict"><code>-Wrestrict</code></a>
+ detects overlapping accesses to dynamically allocated objects.
+ </li>
+ <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wreturn-local-addr"><code>-Wreturn-local-addr</code></a>
+ diagnoses more instances of <code>return</code> statements returning
+ addresses of automatic variables.
+ </li>
+ <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wstringop-overflow"><code>-Wstringop-overflow</code></a>
+ detects more out-of-bounds stores to member arrays including
+ zero-length arrays, dynamically allocated objects and variable length
+ arrays, as well as more instances of reads of unterminated character
+ arrays by string built-in functions. The warning also detects
+ out-of-bounds accesses by calls to user-defined functions declared
+ with the new attribute <code>access</code>.
+ </li>
+ </ul>
+</ul>
<h3 id="c">C</h3>
<ul>
@@ -185,6 +254,21 @@ a work-in-progress.</p>
<code>initializer-list</code></li>
</ul>
</li>
+ <li>New warnings:
+ <ul>
+ <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wmismatched-tags"><code>-Wmismatched-tags</code></a>,
+ disabled by default, warns about declarations of structs, classes,
+ and class templates and their specializations with a class-key that
+ does not match either the definition or the first declaration if no
+ definition is provided. The option is provided to ease portability
+ to Windows-based compilers.
+ </li>
+ <li><a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wredundant-tags"><code>-Wredundant-tags</code></a>,
+ disabled by default, warns about redundant <i>class-key</i> and
+ <i>enum-key</i> in contexts where the key can be eliminated without
+ causing an syntactic ambiguity.
+ </li>
+ </ul>
<li>
G++ can now detect modifying constant objects in constexpr evaluation
(which is undefined behavior).
@@ -461,7 +545,7 @@ a work-in-progress.</p>
and without the need to provide options <code>-B</code> and
<code>-mmcu=</code>.
See
- <a href="https://gcc.gnu.org/onlinedocs/gcc/AVR-Options.html#index-nodevicespecs">AVR
+ <a href="https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/AVR-Options.html#index-nodevicespecs">AVR
command-line options</a> for details.
This feature is also available in GCC 9.3+ and GCC 8.4+.
</li>