On 05/08/2012 04:10 AM, Jason Merrill wrote:
How do we even get to calling cp_truthvalue_conversion?
ocp_convert wants to do that, around line 750... And I have a brand new
proposal ;)
The patchlet below (which passes testing) leads to very consistent error
messages for the testcase in the PR, and:
void foo();
void bar(int a, int b)
{
if (foo())
;
}
and
void foo();
void bar(int a, int b)
{
if (foo() && a < b)
;
}
exactly the same actually. But maybe we want to differentiate somehow
what we emit for lambdas, but I don't think we want the status quo for
%qE for a lambda here, because it would be:
error: could not convert ‘b.main()::<lambda()>()’ from ‘void’ to ‘bool’
What do you think?
Thanks!
Paolo.
///////////////////////////
Index: testsuite/g++.dg/cpp0x/lambda/lambda-err2.C
===================================================================
--- testsuite/g++.dg/cpp0x/lambda/lambda-err2.C (revision 0)
+++ testsuite/g++.dg/cpp0x/lambda/lambda-err2.C (revision 0)
@@ -0,0 +1,12 @@
+// PR c++/53158
+// { dg-do compile { target c++11 } }
+
+int main()
+{
+ auto a = []() { return true; };
+ auto b = []() { return a(); }; // { dg-error "'a' is not captured" }
+ int c, d;
+ while (b() && c < d) // { dg-error "could not convert 'b\\(\\)' from 'void'
to 'bool'" }
+ {
+ }
+}
Index: cp/error.c
===================================================================
--- cp/error.c (revision 187249)
+++ cp/error.c (working copy)
@@ -1897,6 +1897,13 @@ dump_expr (tree t, int flags)
if (TREE_CODE (ob) == ADDR_EXPR)
{
dump_expr (TREE_OPERAND (ob, 0), flags | TFF_EXPR_IN_PARENS);
+ /* Handle lambdas specially. */
+ if (TREE_CODE (fn) == FUNCTION_DECL
+ && DECL_NAME (fn) && LAMBDA_FUNCTION_P (fn))
+ {
+ dump_call_expr_args (t, flags, true);
+ return;
+ }
pp_cxx_dot (cxx_pp);
}
else if (TREE_CODE (ob) != PARM_DECL
Index: cp/cvt.c
===================================================================
--- cp/cvt.c (revision 187249)
+++ cp/cvt.c (working copy)
@@ -743,6 +743,12 @@ ocp_convert (tree type, tree expr, int convtype, i
}
if (code == BOOLEAN_TYPE)
{
+ if (TREE_CODE (intype) == VOID_TYPE)
+ {
+ error ("could not convert %qE from %<void%> to %<bool%>", expr);
+ return error_mark_node;
+ }
+
/* We can't implicitly convert a scoped enum to bool, so convert
to the underlying type first. */
if (SCOPED_ENUM_P (intype) && (convtype & CONV_STATIC))
