* [PATCH] Fix Rust parser bug with function fields
@ 2022-01-25 1:35 Tom Tromey
2022-02-06 20:23 ` Tom Tromey
0 siblings, 1 reply; 2+ messages in thread
From: Tom Tromey @ 2022-01-25 1:35 UTC (permalink / raw)
To: gdb-patches; +Cc: Tom Tromey
In Rust, 'obj.f()' is a method call -- but '(obj.f)()' is a call of a
function-valued field 'f' in 'obj'. The Rust parser in gdb currently
gets this wrong. This is PR rust/24082.
The expression and Rust parser rewrites made this simple to fix --
simply wrapping a parenthesized expression in a new operation handles
it. This patch has a slight hack because I didn't want to introduce a
new exp_opcode enumeration constant just for this. IMO this doesn't
matter, since we should work toward removing dependencies on these
opcodes anyway; but let me know what you think of this.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=24082
---
gdb/rust-exp.h | 27 +++++++++++++++++++++
gdb/rust-parse.c | 2 +-
gdb/testsuite/gdb.rust/fnfield.exp | 38 +++++++++++++++++++++++++++++
gdb/testsuite/gdb.rust/fnfield.rs | 39 ++++++++++++++++++++++++++++++
4 files changed, 105 insertions(+), 1 deletion(-)
create mode 100644 gdb/testsuite/gdb.rust/fnfield.exp
create mode 100644 gdb/testsuite/gdb.rust/fnfield.rs
diff --git a/gdb/rust-exp.h b/gdb/rust-exp.h
index 6a24f2cbc10..778d87f4078 100644
--- a/gdb/rust-exp.h
+++ b/gdb/rust-exp.h
@@ -197,6 +197,33 @@ class rust_aggregate_operation
{ return OP_AGGREGATE; }
};
+/* Rust parenthesized operation. This is needed to distinguish
+ between 'obj.f()', which is a method call, and '(obj.f)()', which
+ is a call of a function-valued field 'f'. */
+class rust_parenthesized_operation
+ : public tuple_holding_operation<operation_up>
+{
+public:
+
+ explicit rust_parenthesized_operation (operation_up op)
+ : tuple_holding_operation (std::move (op))
+ {
+ }
+
+ value *evaluate (struct type *expect_type,
+ struct expression *exp,
+ enum noside noside) override
+ {
+ return std::get<0> (m_storage)->evaluate (expect_type, exp, noside);
+ }
+
+ enum exp_opcode opcode () const override
+ {
+ /* A lie but this isn't worth introducing a new opcode for. */
+ return UNOP_PLUS;
+ }
+};
+
} /* namespace expr */
#endif /* RUST_EXP_H */
diff --git a/gdb/rust-parse.c b/gdb/rust-parse.c
index 31a1ee3b38f..894f2e79d49 100644
--- a/gdb/rust-parse.c
+++ b/gdb/rust-parse.c
@@ -1105,7 +1105,7 @@ rust_parser::parse_tuple ()
{
/* Parenthesized expression. */
lex ();
- return expr;
+ return make_operation<rust_parenthesized_operation> (std::move (expr));
}
std::vector<operation_up> ops;
diff --git a/gdb/testsuite/gdb.rust/fnfield.exp b/gdb/testsuite/gdb.rust/fnfield.exp
new file mode 100644
index 00000000000..45755710626
--- /dev/null
+++ b/gdb/testsuite/gdb.rust/fnfield.exp
@@ -0,0 +1,38 @@
+# Copyright (C) 2022 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# Test trait object printing.
+
+load_lib rust-support.exp
+if {[skip_rust_tests]} {
+ continue
+}
+
+standard_testfile .rs
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug rust}]} {
+ return -1
+}
+
+set line [gdb_get_line_number "set breakpoint here"]
+if {![runto ${srcfile}:$line]} {
+ untested "could not run to breakpoint"
+ return -1
+}
+
+gdb_test "print foo.f()" " = 6" "call impl function"
+gdb_test "print (foo.f)()" " = 5" "call function field"
+gdb_test "print foo.g()" " = 7" "call impl function g"
+gdb_test "print (foo.g)()" "There is no member named g." \
+ "cannot call g with parens"
diff --git a/gdb/testsuite/gdb.rust/fnfield.rs b/gdb/testsuite/gdb.rust/fnfield.rs
new file mode 100644
index 00000000000..b80136c057f
--- /dev/null
+++ b/gdb/testsuite/gdb.rust/fnfield.rs
@@ -0,0 +1,39 @@
+// Copyright (C) 2022 Free Software Foundation, Inc.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+#![allow(warnings)]
+
+fn five() -> i32 { 5 }
+
+fn main() {
+ let foo = Foo {x: 5, f: five};
+ foo.print(); // set breakpoint here
+ println!("Hello, world! {}, {}, {}", foo.f(), (foo.f)(),
+ foo.g ());
+}
+
+struct Foo {
+ x :i32,
+ f: fn () -> i32,
+}
+
+impl Foo {
+ fn print(&self) {
+ println!("hello {}", self.x)
+ }
+
+ fn f(&self) -> i32 { 6 }
+ fn g(&self) -> i32 { 7 }
+}
--
2.31.1
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] Fix Rust parser bug with function fields
2022-01-25 1:35 [PATCH] Fix Rust parser bug with function fields Tom Tromey
@ 2022-02-06 20:23 ` Tom Tromey
0 siblings, 0 replies; 2+ messages in thread
From: Tom Tromey @ 2022-02-06 20:23 UTC (permalink / raw)
To: Tom Tromey; +Cc: gdb-patches
>>>>> "Tom" == Tom Tromey <tom@tromey.com> writes:
Tom> In Rust, 'obj.f()' is a method call -- but '(obj.f)()' is a call of a
Tom> function-valued field 'f' in 'obj'. The Rust parser in gdb currently
Tom> gets this wrong. This is PR rust/24082.
I'm checking this in.
Tom
^ permalink raw reply [flat|nested] 2+ messages in thread
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