[committed] c++: Add -std=c++20.

Message ID 20200215212149.26959-1-jason@redhat.com
State New
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  • [committed] c++: Add -std=c++20.
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Commit Message

Jason Merrill Feb. 15, 2020, 9:21 p.m.
It's probably past time for this, but definitely now that we're done with
the final committee meeting of C++20.  This patch only adds the option and
adjusts the testsuite to recognize it; more extensive changes can wait for
the published standard.

Tested x86_64-pc-linux-gnu, applying to trunk.

gcc/ChangeLog
2020-02-15  Jason Merrill  <jason@redhat.com>

	* doc/invoke.texi (C Dialect Options): Add -std=c++20.

gcc/c-family/ChangeLog
2020-02-15  Jason Merrill  <jason@redhat.com>

	* c.opt: Add -std=c++20.

gcc/testsuite/ChangeLog
2020-02-15  Jason Merrill  <jason@redhat.com>

	* lib/target-supports.exp (check_effective_target_c++2a_only): Also
	look for -std=*++20.
	(check_effective_target_concepts): Use check_effective_target_c++2a.
---
 gcc/doc/invoke.texi                   | 10 ++++++----
 gcc/c-family/c.opt                    |  6 +++++-
 gcc/testsuite/lib/target-supports.exp |  9 ++++++---
 3 files changed, 17 insertions(+), 8 deletions(-)


base-commit: 0b3c2eed35d608d6541ecf004a9576b4eae0b4ef
-- 
2.18.1

Patch

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 597151670be..3e47d06f0d5 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -2078,13 +2078,15 @@  The name @samp{c++1z} is deprecated.
 GNU dialect of @option{-std=c++17}.
 The name @samp{gnu++1z} is deprecated.
 
-@item c++2a
-The next revision of the ISO C++ standard, tentatively planned for
+@item c++20
+@itemx c++2a
+The next revision of the ISO C++ standard, planned for
 2020.  Support is highly experimental, and will almost certainly
 change in incompatible ways in future releases.
 
-@item gnu++2a
-GNU dialect of @option{-std=c++2a}.  Support is highly experimental,
+@item gnu++20
+@itemx gnu++2a
+GNU dialect of @option{-std=c++20}.  Support is highly experimental,
 and will almost certainly change in incompatible ways in future
 releases.
 @end table
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 814ed17f7c4..b7e4fe146b2 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -2071,7 +2071,11 @@  Conform to the ISO 2017 C++ standard.
 
 std=c++2a
 C++ ObjC++
-Conform to the ISO 2020(?) C++ draft standard (experimental and incomplete support).
+Conform to the ISO 2020 C++ draft standard (experimental and incomplete support).
+
+std=c++20
+C++ ObjC++ Alias(std=c++2a)
+Conform to the ISO 2020 C++ draft standard (experimental and incomplete support).
 
 std=c11
 C ObjC
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index fb177c54aa8..ec462315860 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -8806,7 +8806,7 @@  proc check_effective_target_c++2a_only { } {
     if ![check_effective_target_c++] {
 	return 0
     }
-    if [check-flags { { } { } { -std=c++2a -std=gnu++2a } }] {
+    if [check-flags { { } { } { -std=c++2a -std=gnu++2a -std=c++20 -std=gnu++20 } }] {
 	return 1
     }
     if { $cxx_default == "c++20" && [check-flags { { } { } { } { -std=* } }] } {
@@ -8818,9 +8818,12 @@  proc check_effective_target_c++2a { } {
     return [check_effective_target_c++2a_only]
 }
 
-# Check for C++ Concepts TS support, i.e. -fconcepts flag.
+# Check for C++ Concepts support, i.e. -fconcepts flag.
 proc check_effective_target_concepts { } {
-    return [check-flags { "" { } { -fconcepts -std=*2a } }]
+    if [check_effective_target_c++2a] {
+	return 1
+    }
+    return [check-flags { "" { } { -fconcepts } }]
 }
 
 # Return 1 if expensive testcases should be run.