From a7201a085cc30f89944931d8fb1d7936f02a169f Mon Sep 17 00:00:00 2001
From: Patrick Palka <ppalka@redhat.com>
Date: Wed, 29 Apr 2020 09:04:58 -0400
Subject: [PATCH] c++: Nondeterministic concepts diagnostics [PR94830]
This patch makes the order in which template parameters appear in the
TREE_LIST returned by find_template_parameters deterministic between
runs.
The current nondeterminism is semantically harmless, but it has the
undesirable effect of causing some concepts diagnostics which print a
constraint's parameter mapping via pp_cxx_parameter_mapping to also be
nondeterministic, as in the testcases below.
gcc/cp/ChangeLog:
PR c++/94830
* pt.c (find_template_parameter_info::parm_list): New field.
(keep_template_parm): Use the new field to build up the
parameter list here instead of ...
(find_template_parameters): ... here. Return ftpi.parm_list.
gcc/testsuite/ChangeLog:
PR c++/94830
* g++.dg/concepts/diagnostics12.C: Clarify the dg-message now
that the corresponding diagnostic is deterministic.
* g++.dg/concepts/diagnostics13.C: New test.
---
gcc/cp/ChangeLog | 8 ++++++++
gcc/cp/pt.c | 13 ++++++-------
gcc/testsuite/ChangeLog | 7 +++++++
gcc/testsuite/g++.dg/concepts/diagnostic12.C | 2 +-
gcc/testsuite/g++.dg/concepts/diagnostic13.C | 14 ++++++++++++++
5 files changed, 36 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/concepts/diagnostic13.C
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 41db16e782fa..cbedbabe3a64 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,11 @@
+2020-04-29 Patrick Palka <ppalka@redhat.com>
+
+ PR c++/94830
+ * pt.c (find_template_parameter_info::parm_list): New field.
+ (keep_template_parm): Use the new field to build up the
+ parameter list here instead of ...
+ (find_template_parameters): ... here. Return ftpi.parm_list.
+
2020-04-29 Jakub Jelinek <jakub@redhat.com>
PR target/94707
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index ba22d9ec5388..d28585efd17a 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -10439,12 +10439,14 @@ for_each_template_parm (tree t, tree_fn_t fn, void* data,
struct find_template_parameter_info
{
explicit find_template_parameter_info (tree ctx_parms)
- : ctx_parms (ctx_parms),
+ : parm_list (NULL_TREE),
+ ctx_parms (ctx_parms),
max_depth (TMPL_PARMS_DEPTH (ctx_parms))
{}
hash_set<tree> visited;
hash_set<tree> parms;
+ tree parm_list;
tree ctx_parms;
int max_depth;
};
@@ -10476,7 +10478,8 @@ keep_template_parm (tree t, void* data)
T and const T. Adjust types to their unqualified versions. */
if (TYPE_P (t))
t = TYPE_MAIN_VARIANT (t);
- ftpi->parms.add (t);
+ if (!ftpi->parms.add (t))
+ ftpi->parm_list = tree_cons (NULL_TREE, t, ftpi->parm_list);
return 0;
}
@@ -10587,11 +10590,7 @@ find_template_parameters (tree t, tree ctx_parms)
find_template_parameter_info ftpi (ctx_parms);
for_each_template_parm (t, keep_template_parm, &ftpi, &ftpi.visited,
/*include_nondeduced*/true, any_template_parm_r);
- tree list = NULL_TREE;
- for (hash_set<tree>::iterator iter = ftpi.parms.begin();
- iter != ftpi.parms.end(); ++iter)
- list = tree_cons (NULL_TREE, *iter, list);
- return list;
+ return ftpi.parm_list;
}
/* Returns true if T depends on any template parameter. */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b635ce1939d6..0fce8fba0a41 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2020-04-29 Patrick Palka <ppalka@redhat.com>
+
+ PR c++/94830
+ * g++.dg/concepts/diagnostics12.C: Clarify the dg-message now
+ that the corresponding diagnostic is deterministic.
+ * g++.dg/concepts/diagnostics13.C: New test.
+
2020-04-29 H.J. Lu <hongjiu.lu@intel.com>
PR target/93654
diff --git a/gcc/testsuite/g++.dg/concepts/diagnostic12.C b/gcc/testsuite/g++.dg/concepts/diagnostic12.C
index a757342f7546..548ba9c1b3d0 100644
--- a/gcc/testsuite/g++.dg/concepts/diagnostic12.C
+++ b/gcc/testsuite/g++.dg/concepts/diagnostic12.C
@@ -3,7 +3,7 @@
template<typename T, typename... Args>
concept c1 = requires (T t, Args... args) { *t; };
-// { dg-message "in requirements with .T t., .Args ... args. .with.* Args = \{\}" "" { target *-*-* } .-1 }
+// { dg-message "in requirements with .T t., .Args ... args. .with Args = \{\}; T = int" "" { target *-*-* } .-1 }
static_assert(c1<int>); // { dg-error "failed" }
diff --git a/gcc/testsuite/g++.dg/concepts/diagnostic13.C b/gcc/testsuite/g++.dg/concepts/diagnostic13.C
new file mode 100644
index 000000000000..accd8a6d2bdb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/diagnostic13.C
@@ -0,0 +1,14 @@
+// PR c++/94830
+// { dg-do compile { target concepts } }
+
+template<typename T, typename R>
+ concept c = __is_same(T, R); // { dg-message "with T = int; R = char" }
+
+template<typename T, typename R>
+ requires c<T,R>
+void foo() { }
+
+void bar()
+{
+ foo<int, char>(); // { dg-error "unsatisfied constraints" }
+}
--
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