Hi,
The principle of Objective-c/c++ is that they should be supersets of the parent
language. Thus, it is intended that valid c++ (or c) should be parsed by the
relevant objective-c/c++ FE.
While trying to build some external code, I found that lambdas confuse things
at present for objcp.
When we find "[" and we're in objcp mode, and the "[" introduces a lambda, we
try to parse a message expression and if that fails we punt (thus we are unable
to recognise lambdas).
The attached patch tries "[" as a message expression introducer, if that fails
it drops through to try for a lambda (no change intended for the
non-objective-c++ path).
I guess it's a bit of a nuisance that the diagnostics from a failed message
expression are likely to end up as mentioning a lambda. Perhaps we might
decide to punt early if we are both ObjC and < c++11.
This allows me to parse some necessary lldb headers with gcc objcp.
Thoughts / OK for trunk?
(I can raise a formal PR if you like).
Iain
gcc/cp:
* parser.c (cp_parser_primary_expression): If parsing an objective-c++
message
expression fails, see if a lambda is present.
(cp_parser_objc_message_reciever): Don't assume that if a message
reciever expression
fails it is a hard error.
gcc/testsuite:
* obj-c++.dg/lambda-0.mm New file.
* obj-c++.dg/lambda-1.mm New file.
From e8038ba3cb16095e53d09e23ff15f4682cb5bd0c Mon Sep 17 00:00:00 2001
From: Iain Sandoe <[email protected]>
Date: Mon, 22 Dec 2014 10:50:45 +0000
Subject: [PATCH] Modify objective-c++ parse to check for lambdas when a
message construct isn't matched after a [
---
gcc/cp/parser.c | 21 +++++++++++++++++----
gcc/testsuite/obj-c++.dg/lambda-0.mm | 22 ++++++++++++++++++++++
gcc/testsuite/obj-c++.dg/lambda-1.mm | 13 +++++++++++++
gcc/testsuite/obj-c++.dg/syntax-error-6.mm | 5 ++++-
4 files changed, 56 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/obj-c++.dg/lambda-0.mm
create mode 100644 gcc/testsuite/obj-c++.dg/lambda-1.mm
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 8ff16ed..1409bef 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -4441,10 +4441,17 @@ cp_parser_primary_expression (cp_parser *parser,
}
case CPP_OPEN_SQUARE:
- if (c_dialect_objc ())
- /* We have an Objective-C++ message. */
- return cp_parser_objc_expression (parser);
{
+ if (c_dialect_objc ())
+ {
+ /* We might have an Objective-C++ message. */
+ cp_parser_parse_tentatively (parser);
+ tree msg = cp_parser_objc_message_expression (parser);
+ /* If that works out, we're done ... */
+ if (cp_parser_parse_definitely (parser))
+ return msg;
+ /* ... else, fall though to see if it's a lambda. */
+ }
tree lam = cp_parser_lambda_expression (parser);
/* Don't warn about a failed tentative parse. */
if (cp_parser_error_occurred (parser))
@@ -25630,14 +25637,20 @@ cp_parser_objc_message_receiver (cp_parser* parser)
cp_parser_parse_tentatively (parser);
rcv = cp_parser_expression (parser);
+ /* If that worked out, fine. */
if (cp_parser_parse_definitely (parser))
return rcv;
+ cp_parser_parse_tentatively (parser);
rcv = cp_parser_simple_type_specifier (parser,
/*decl_specs=*/NULL,
CP_PARSER_FLAGS_NONE);
- return objc_get_class_reference (rcv);
+ if (cp_parser_parse_definitely (parser))
+ return objc_get_class_reference (rcv);
+
+ cp_parser_error (parser, "objective-c++ message receiver expected");
+ return error_mark_node;
}
/* Parse the arguments and selectors comprising an Objective-C message.
diff --git a/gcc/testsuite/obj-c++.dg/lambda-0.mm
b/gcc/testsuite/obj-c++.dg/lambda-0.mm
new file mode 100644
index 0000000..41482fd
--- /dev/null
+++ b/gcc/testsuite/obj-c++.dg/lambda-0.mm
@@ -0,0 +1,22 @@
+// Contributed by Iain Sandoe <[email protected]>, December 2014. */
+// { dg-do compile }
+// { dg-options "-std=c++11" }
+
+
+template<class Function>
+Function thing(Function fn, int a)
+{
+ fn(a);
+ return fn;
+}
+
+int
+test (int *arr, unsigned n)
+{
+ int total = 0;
+ for (unsigned i=0; i<n; i++) {
+ int a = arr[i];
+ thing ([&total] (int a) { total += a; }, a);
+ }
+ return total;
+}
diff --git a/gcc/testsuite/obj-c++.dg/lambda-1.mm
b/gcc/testsuite/obj-c++.dg/lambda-1.mm
new file mode 100644
index 0000000..050d68d
--- /dev/null
+++ b/gcc/testsuite/obj-c++.dg/lambda-1.mm
@@ -0,0 +1,13 @@
+// Contributed by Iain Sandoe <[email protected]>, December 2014. */
+// { dg-do compile }
+// { dg-options "-std=c++11" }
+
+extern "C" {
+ int printf (const char *,...);
+}
+
+int main ()
+{
+ auto f = [] (const char *msg) -> int { printf("%s", msg); return 0; };
+ return f("Some test\n");
+}
diff --git a/gcc/testsuite/obj-c++.dg/syntax-error-6.mm
b/gcc/testsuite/obj-c++.dg/syntax-error-6.mm
index 21423ec..36a444f 100644
--- a/gcc/testsuite/obj-c++.dg/syntax-error-6.mm
+++ b/gcc/testsuite/obj-c++.dg/syntax-error-6.mm
@@ -8,5 +8,8 @@ void FOO()
{
NSButton * mCopyAcrobatCB;
- [ [ mCopyAcrobatCB state ] == 0 ] != 1; /* { dg-error "objective\\-c\\+\\+"
} */
+ [ [ mCopyAcrobatCB state ] == 0 ] != 1; /* { dg-error "expected identifier
before ... token" } */
+/* { dg-error "expected \\\'\\\{\\\' before \\\'!=\\\' token" "" { target
*-*-* } 11 } */
+/* { dg-error "lambda expressions only available with" "" { target *-*-* } 11
} */
+/* { dg-error "no match for \\\'operator!=\\\' in" "" { target *-*-* } 11 } */
}
--
1.8.4.2
