[gcc r13-1688] c++: non-dependent call to consteval operator [PR105912]

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

https://gcc.gnu.org/g:f70c18524221dcefa6cd26cee7b55503181bd912

commit r13-1688-gf70c18524221dcefa6cd26cee7b55503181bd912
Author: Patrick Palka <ppalka@redhat.com>
Date:   Wed Jul 13 14:02:08 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:
    
            * 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.

Diff:
---
 gcc/cp/pt.cc                             | 12 ++++++------
 gcc/testsuite/g++.dg/cpp2a/consteval31.C | 26 ++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index da00ce1301a..718dfa5bfa8 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -21206,12 +21206,12 @@ 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>();