[gcc r12-8606] c++: non-dependent call to consteval operator [PR105912]

[Patrick Palka <ppalka@gcc.gnu.org>]

https://gcc.gnu.org/g:a074ae297d5dbd69e03c6c30f9cb7720685fdb62

commit r12-8606-ga074ae297d5dbd69e03c6c30f9cb7720685fdb62
Author: Patrick Palka <ppalka@redhat.com>
Date:   Thu Jul 21 12:59:44 2022 -0400

    c++: non-dependent call to consteval operator [PR105912]
    
    Here we're crashing when substituting a non-dependent call to a
    consteval operator, whose CALL_EXPR_OPERATOR_SYNTAX flag we try to
    propagate to the result, but the result isn't a CALL_EXPR since the
    selected function is consteval.  This patch fixes this by checking the
    result of extract_call_expr accordingly.  (Note that we can't check
    DECL_IMMEDIATE_FUNCTION_P here because we don't know which function was
    selected by overload resolution from here.)
    
            PR c++/105912
    
    gcc/cp/ChangeLog:
    
            * call.cc (extract_call_expr): Return a NULL_TREE on failure
            instead of asserting.
            * pt.cc (tsubst_copy_and_build) <case CALL_EXPR>: Guard against
            NULL_TREE extract_call_expr result.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp2a/consteval31.C: New test.
    
    (cherry picked from commit f70c18524221dcefa6cd26cee7b55503181bd912)

Diff:
---
 gcc/cp/call.cc                           |  7 ++++---
 gcc/cp/pt.cc                             | 12 ++++++------
 gcc/testsuite/g++.dg/cpp2a/consteval31.C | 26 ++++++++++++++++++++++++++
 3 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index dafcdb08acb..67c30f380f2 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -7116,9 +7116,10 @@ extract_call_expr (tree call)
       default:;
       }
 
-  gcc_assert (TREE_CODE (call) == CALL_EXPR
-	      || TREE_CODE (call) == AGGR_INIT_EXPR
-	      || call == error_mark_node);
+  if (TREE_CODE (call) != CALL_EXPR
+      && TREE_CODE (call) != AGGR_INIT_EXPR
+      && call != error_mark_node)
+    return NULL_TREE;
   return call;
 }
 
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index cf4ae7775da..80fadead0f7 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -21069,12 +21069,12 @@ tsubst_copy_and_build (tree t,
 	    bool ord = CALL_EXPR_ORDERED_ARGS (t);
 	    bool rev = CALL_EXPR_REVERSE_ARGS (t);
 	    if (op || ord || rev)
-	      {
-		function = extract_call_expr (ret);
-		CALL_EXPR_OPERATOR_SYNTAX (function) = op;
-		CALL_EXPR_ORDERED_ARGS (function) = ord;
-		CALL_EXPR_REVERSE_ARGS (function) = rev;
-	      }
+	      if (tree call = extract_call_expr (ret))
+		{
+		  CALL_EXPR_OPERATOR_SYNTAX (call) = op;
+		  CALL_EXPR_ORDERED_ARGS (call) = ord;
+		  CALL_EXPR_REVERSE_ARGS (call) = rev;
+		}
 	  }
 
 	RETURN (ret);
diff --git a/gcc/testsuite/g++.dg/cpp2a/consteval31.C b/gcc/testsuite/g++.dg/cpp2a/consteval31.C
new file mode 100644
index 00000000000..85a4d1794e5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/consteval31.C
@@ -0,0 +1,26 @@
+// PR c++/105912
+// { dg-do compile { target c++20 } }
+
+struct A {
+  consteval A operator+() {
+    return {};
+  }
+};
+
+consteval A operator~(A) {
+  return {};
+}
+
+consteval A operator+(A, A) {
+  return {};
+}
+
+template<class>
+void f() {
+  A a;
+  ~a;
+  a + a;
+  +a;
+}
+
+template void f<int>();