[C++ PATCH] PR60531 - Wrong error about unresolved overloaded function

[Harald van Dijk <harald@gigawatt.nl>]

Hi,

For PR60531, GCC wrongly rejects function templates with explicitly
specified template arguments as overloaded. They are resolved by
resolve_nondeduced_context, which is normally called by
cp_default_conversion through decay_conversion, but the latter have
extra effects making them unusable here. Calling the former directly
does work.

Bootstrapped on x86_64-pc-linux-gnu on top of r270264 with
--enable-languages=all; make check shows no regressions.

Does this look okay?

This is my first code contribution to GCC, please let me know if
anything is missing. I have not signed any copyright disclaimer or
copyright assignment; <Contributing to GCC> says that is not necessary
for small changes, which I trust this is. If it is needed after all,
please let me know what specifically will be required.

Cheers,
Harald van Dijk

	PR c++/60531
	* typeck.c (cp_build_binary_op): See if overload can be resolved.
	(cp_build_unary_op): Ditto.

	* g++.dg/template/operator15.C: New test.

diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 03b14024738..e1ffe88ce2c 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -4384,10 +4384,6 @@ cp_build_binary_op (const op_location_t &location,
    /* True if both operands have arithmetic type.  */
    bool arithmetic_types_p;

-  /* Apply default conversions.  */
-  op0 = orig_op0;
-  op1 = orig_op1;
-
    /* Remember whether we're doing / or %.  */
    bool doing_div_or_mod = false;

@@ -4397,6 +4393,10 @@ cp_build_binary_op (const op_location_t &location,
    /* Tree holding instrumentation expression.  */
    tree instrument_expr = NULL_TREE;

+  /* Apply default conversions.  */
+  op0 = resolve_nondeduced_context (orig_op0, complain);
+  op1 = resolve_nondeduced_context (orig_op1, complain);
+
    if (code == TRUTH_AND_EXPR || code == TRUTH_ANDIF_EXPR
        || code == TRUTH_OR_EXPR || code == TRUTH_ORIF_EXPR
        || code == TRUTH_XOR_EXPR)
@@ -6204,11 +6204,13 @@ cp_build_unary_op (enum tree_code code, tree xarg, bool noconvert,
    if (!arg || error_operand_p (arg))
      return error_mark_node;

+  arg = resolve_nondeduced_context (arg, complain);
+
    if ((invalid_op_diag
         = targetm.invalid_unary_op ((code == UNARY_PLUS_EXPR
  				    ? CONVERT_EXPR
  				    : code),
-				   TREE_TYPE (xarg))))
+				   TREE_TYPE (arg))))
      {
        if (complain & tf_error)
  	error (invalid_op_diag);
diff --git a/gcc/testsuite/g++.dg/template/operator15.C b/gcc/testsuite/g++.dg/template/operator15.C
new file mode 100644
index 00000000000..755442266bb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/operator15.C
@@ -0,0 +1,6 @@
+// PR c++/60531
+
+template < class T > T foo ();
+
+bool b1 = foo<int> == foo<int>;
+int (*fp1)() = +foo<int>;