[wwwdocs,committed] My changes to gcc-9/changes.html (v2)

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Headers	show Return-Path: <gcc-patches-return-498329-incoming=patchwork.ozlabs.org@gcc.gnu.org> DomainKey-Signature: a=rsa-sha1; c=nofws; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender:from :to:cc:subject:date:message-id:in-reply-to:references; q=dns; s= default; b=gSEBujwsHtQsVP3WWGOTyIXeEGDcvOJWqbT+V2Ff+7fF7WlRSmpAt qyNZiTs5xrJ6nxy4zvA0NJ4CxDSQkgHe/uB3g5AWtD4wl18IzEkv6IMvd6ydnaIR xZlUihN7mXFs6X1wopwxjv5kR+mVvycG+PiJ0btytZ5yR0YspSmfq0= Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk Sender: gcc-patches-owner@gcc.gnu.org From: David Malcolm <dmalcolm@redhat.com> To: Sandra Loosemore <sandra@codesourcery.com>, Gerald Pfeifer <gerald@pfeifer.com> Cc: gcc-patches@gcc.gnu.org, David Malcolm <dmalcolm@redhat.com> Subject: [wwwdocs, committed] My changes to gcc-9/changes.html (v2) Date: Fri, 22 Mar 2019 18:15:29 -0400 Message-Id: <1553292929-29653-1-git-send-email-dmalcolm@redhat.com> In-Reply-To: <60f1f042-b4b4-5319-e898-44f610349547@codesourcery.com> References: <60f1f042-b4b4-5319-e898-44f610349547@codesourcery.com>
Series	[wwwdocs,committed] My changes to gcc-9/changes.html (v2) \| expand [wwwdocs,committed] My changes to gcc-9/changes.html (v2)

diff --git a/htdocs/gcc-9/changes.html b/htdocs/gcc-9/changes.html index 5a50b5d..8410b12 100644 --- a/htdocs/gcc-9/changes.html +++ b/htdocs/gcc-9/changes.html @@ -17,7 +17,7 @@ This page is a "brief" summary of some of the huge number of improvements in GCC 9.  @@ -82,6 +82,40 @@ a work-in-progress. option completion in a shell. It is intended to be used by Bash-completion. </li> <li> + + GCC's diagnostics now print source code with a left margin showing line + numbers, configurable with + <a href="https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Message-Formatting-Options.html#index-fno-diagnostics-show-line-numbers">-fno-diagnostics-show-line-numbers</a>. + + + GCC's diagnostics can also now label regions of the source code to + show pertinent information, such as the types within an expression. + +<pre class="blackbg"> +$ g++ t.cc +t.cc: In function 'int test(const shape&, const shape&)': +t.cc:15:4: error: no match for 'operator+' (operand types are 'boxed_value<double>' and 'boxed_value<double>') + 14 | return (width(s1) * height(s1) + | ~~~~~~~~~~~~~~~~~~~~~~ + | | + | boxed_value<[...]> + 15 | + width(s2) * height(s2)); + | ^ ~~~~~~~~~~~~~~~~~~~~~~ + | | + | boxed_value<[...]> +</pre> + + + These labels can be disabled via + <a href="https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Message-Formatting-Options.html#index-fno-diagnostics-show-labels">-fno-diagnostics-show-labels</a>. + + </li> + <li> + A new option <a href="https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Message-Formatting-Options.html#index-fdiagnostics-format">-fdiagnostics-format=json</a> + has been introduced for emitting diagnostics in a machine-readable + format. + </li> + <li> The alignment-related options <a href="https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-falign-functions"><code>-falign-functions</code></a>, <a href="https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-falign-labels"><code>-falign-labels</code></a>, <a href="https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-falign-loops"><code>-falign-loops</code></a>, @@ -97,6 +131,65 @@ a work-in-progress. AddressSanitizer generates more compact redzones for automatic variables. That helps to reduce memory footprint of a sanitized binary. </li> + <li> + + Numerous improvements have been made to the output of + <a href="https://gcc.gnu.org/onlinedocs/gcc/Developer-Options.html#index-fopt-info">-fopt-info</a>. + + Messages are now prefixed with <code>optimized</code>, + <code>missed</code>, or <code>note</code>, rather than the old + behavior of all being prefixed with <code>note</code>. + + + The output from <code>-fopt-info</code> can now contain information + on inlining decisions: + +<pre class="blackbg"> +$ g++ -c inline.cc -O2 -fopt-info-inline-all +inline.cc:24:11: note: Considering inline candidate void foreach(T, T, void (*)(E)) [with T = char**; E = char*]/2. +inline.cc:24:11: optimized: Inlining void foreach(T, T, void (*)(E)) [with T = char**; E = char*]/2 into int main(int, char**)/1. +inline.cc:19:12: missed: not inlinable: void inline_me(char*)/0 -> int std::puts(const char*)/3, function body not available +inline.cc:13:8: optimized: Inlined void inline_me(char*)/4 into int main(int, char**)/1 which now has time 127.363637 and size 11, net change of +0. +Unit growth for small function inlining: 16->16 (0%) + +Inlined 2 calls, eliminated 1 functions + +</pre> + + + The output from the vectorizer has been rationalized so that failed + attempts to vectorize a loop are displayed in the form + + <pre> + [LOOP-LOCATION]: couldn't vectorize this loop + [PROBLEM-LOCATION]: because of [REASON] + </pre> + + rather than an exhaustive log of all decisions made by the vectorizer. + For example: + +<pre class="blackbg"> +$ gcc -c v.c -O3 -fopt-info-all-vec +v.c:7:3: missed: couldn't vectorize loop +v.c:10:7: missed: statement clobbers memory: __asm__ __volatile__("" : : : "memory"); +v.c:3:6: note: vectorized 0 loops in function. +v.c:10:7: missed: statement clobbers memory: __asm__ __volatile__("" : : : "memory"); +</pre> + + + The old behavior can be obtained via a new <code>-internals</code> + suboption of <code>-fopt-info</code>. + + </li> + <li> + A new option, + <a href="https://gcc.gnu.org/onlinedocs/gcc/Developer-Options.html#index-fsave-optimization-record">-fsave-optimization-record</a> + has been added, which writes a <code>SRCFILE.opt-record.json.gz</code> + file describing the optimization decisions made by GCC. This is + similar to the output of <code>-fopt-info</code>, but with additional + metadata such as the inlining chain, and profile information (if + available). + </li> </ul> The following built-in functions have been introduced. <ul> @@ -221,7 +314,17 @@ foo (int how) </li> </ul> </li> - + + <li> + If a macro is used with the wrong argument count, the C and C++ front + ends now show the definition of that macro via a <code>note</code>. + </li> + + <li> + The spelling corrector now considers transposed letters, and the + threshold for similarity has been tightened, to avoid nonsensical + suggestions. + </li> </ul> <h3 id="c">C</h3> @@ -278,6 +381,184 @@ foo (int how) see <a href="../projects/cxx-status.html#cxx2a">the C++ status page</a>. </li> + + <li> + The C++ front end now preserves source locations for literals, + <code>id-expression</code>, and <code>mem-initializer</code> for longer. + For example it is now able to pin-point the pertinent locations for + bad initializations such as these +<pre class="blackbg"> +$ g++ -c bad-inits.cc +bad-inits.cc:10:14: error: cannot convert 'json' to 'int' in initialization + 10 | { 3, json::object }, + | ~~~~~~^~~~~~ + | | + | json +bad-inits.cc:14:31: error: initializer-string for array of chars is too long [-fpermissive] + 14 | char buffers[3][5] = { "red", "green", "blue" }; + | ^~~~~~~ +bad-inits.cc: In constructor 'X::X()': +bad-inits.cc:17:13: error: invalid conversion from 'int' to 'void*' [-fpermissive] + 17 | X() : one(42), two(42), three(42) + | ^~ + | | + | int +</pre> + + rather than emitting the error at the final closing parenthesis or + brace. + </li> + + <li> + Error-reporting of overload resolution has been special-cased to make + the case of a single failed candidate easier to read. For example: + +<pre class="blackbg"> +$ g++ param-type-mismatch.cc +param-type-mismatch.cc: In function 'int test(int, const char*, float)': +param-type-mismatch.cc:8:32: error: cannot convert 'const char*' to 'const char**' + 8 | return foo::member_1 (first, second, third); + | ^~~~~~ + | | + | const char* +param-type-mismatch.cc:3:46: note: initializing argument 2 of 'static int foo::member_1(int, const char**, float)' + 3 | static int member_1 (int one, const char **two, float three); + | ~~~~~~~~~~~~~^~~ +</pre> + + + highlights both the problematic argument, and the parameter + that it can't be converted to. + </li> + + <li> + Diagnostics involving binary operators now use color to distinguish the two + operands, and label them separately (as per the example of source + labelling above). + </li> + + <li> + Diagnostics involving function calls now highlight the pertinent parameter + of the declaration in more places. +<pre class="blackbg"> +$ g++ bad-conversion.cc +bad-conversion.cc: In function 'void caller()': +bad-conversion.cc:9:14: error: cannot convert 'bool' to 'void*' + 9 | callee (0, false, 2); + | ^~~~~ + | | + | bool +bad-conversion.cc:3:19: note: initializing argument 2 of 'void callee(int, void*, int)' + 3 | void callee (int, void *, int) + | ^~~~~~ +</pre> + + </li> + + <li> + The C++ front end's implementation of + <a href="https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wformat">-Wformat</a> + now shows precise locations within string literals, and underlines + the pertinent arguments at bogus call sites (the C front end has been + doing this since GCC 7). For example: +<pre class="blackbg"> +$ g++ -c bad-printf.cc -Wall +bad-printf.cc: In function 'void print_field(const char*, float, long int, long int)': +bad-printf.cc:6:17: warning: field width specifier '*' expects argument of type 'int', but argument 3 has type 'long int' [-Wformat=] + 6 | printf ("%s: %*ld ", fieldname, column - width, value); + | ~^~~ ~~~~~~~~~~~~~~ + | | | + | int long int +bad-printf.cc:6:19: warning: format '%ld' expects argument of type 'long int', but argument 4 has type 'double' [-Wformat=] + 6 | printf ("%s: %*ld ", fieldname, column - width, value); + | ~~~^ ~~~~~ + | | | + | long int double + | %*f +</pre> + + </li> + + <li> + The C++ front end has gained new fix-it hints for forgetting the + <code>return *this;</code> needed by various C++ operators: + +<pre class="blackbg"> +$ g++ -c operator.cc +operator.cc: In member function 'boxed_ptr& boxed_ptr::operator=(const boxed_ptr&)': +operator.cc:7:3: warning: no return statement in function returning non-void [-Wreturn-type] + 6 | m_ptr = other.m_ptr; + +++ |+ return *this; + 7 | } + | ^ +</pre> + + + for when the compiler needs a <code>typename</code>: + +<pre class="blackbg"> +$ g++ -c template.cc +template.cc:3:3: error: need 'typename' before 'Traits::type' because 'Traits' is a dependent scope + 3 | Traits::type type; + | ^~~~~~ + | typename +</pre> + + + when trying to use an accessor member as if it were a data member: + +<pre class="blackbg"> +$ g++ -c fncall.cc +fncall.cc: In function 'void hangman(const mystring&)': +fncall.cc:12:11: error: invalid use of member function 'int mystring::get_length() const' (did you forget the '()' ?) + 12 | if (str.get_length > 0) + | ~~~~^~~~~~~~~~ + | () +</pre> + + + for C++11's scoped enums: + +<pre class="blackbg"> +$ g++ -c enums.cc +enums.cc: In function 'void json::test(const json::value&)': +enums.cc:12:26: error: 'STRING' was not declared in this scope; did you mean 'json::kind::STRING'? + 12 | if (v.get_kind () == STRING) + | ^~~~~~ + | json::kind::STRING +enums.cc:3:44: note: 'json::kind::STRING' declared here + 3 | enum class kind { OBJECT, ARRAY, NUMBER, STRING, TRUE, FALSE, NULL_ }; + | ^~~~~~ +</pre> + + + and a tweak to integrate the suggestions about misspelled members + with that for accessors: + +<pre class="blackbg"> +$ g++ -c accessor-fixit.cc +accessor-fixit.cc: In function 'int test(t*)': +accessor-fixit.cc:17:15: error: 'class t' has no member named 'ratio'; did you mean 'int t::m_ratio'? (accessible via 'int t::get_ratio() const') + 17 | return ptr->ratio; + | ^~~~~ + | get_ratio() +</pre> + + + In addition, various diagnostics in the C++ front-end have been + streamlined by consolidating the suggestion into the initial + error, rather than emitting a follow-up note: + +<pre class="blackbg"> +$ g++ typo.cc +typo.cc:5:13: error: 'BUFSIZE' was not declared in this scope; did you mean 'BUF_SIZE'? + 5 | uint8_t buf[BUFSIZE]; + | ^~~~~~~ + | BUF_SIZE +</pre> + + + </li> </ul> <h4 id="libstdcxx">Runtime Library (libstdc++)</h4> @@ -380,7 +661,14 @@ foo (int how)   - +<h2 id="jit">libgccjit</h2> + +<ul> + <li> + The libgccjit API gained a new entry point: + <a href="https://gcc.gnu.org/onlinedocs/jit/topics/contexts.html#gcc_jit_context_add_driver_option">gcc_jit_context_add_driver_option</a>. + </li> +</ul>  <h2 id="targets">New Targets and Target Specific Improvements</h2> @@ -563,11 +851,30 @@ foo (int how)  - +<h2 id="plugins">Improvements for plugin authors</h2> +<ul> + <li> + GCC's diagnostic subsystem now has a way to logically group together + related diagnostics, <code>auto_diagnostic_group</code>. Such + diagnostics will be nested by the output of + <a href="https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Message-Formatting-Options.html#index-fdiagnostics-format">-fdiagnostics-format=json</a>. + </li> - - + <li> + GCC now has a set of + <a href="https://gcc.gnu.org/onlinedocs/gccint/User-Experience-Guidelines.html">user experience guidelines for GCC</a>, + with information and advice on implementing new diagnostics. + </li> +</ul> + +<h2>Other significant improvements</h2> +<ul> + <li> + GCC's internal "selftest" suite now runs for C++ as well as C (in + debug builds of the compiler). + </li> +</ul>

[wwwdocs,committed] My changes to gcc-9/changes.html (v2)

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