From 4d1336653f43d4c9b8854f476575533a159655de Mon Sep 17 00:00:00 2001
From: Rylan Dmello <mail@rylan.coffee>
Date: Thu, 15 Oct 2020 08:43:47 -0400
Subject: [PATCH 1/4] Add error message when assigning to tuple

---
 src/parser.yy | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/parser.yy b/src/parser.yy
index 53293c5a20cd..c815742eacf1 100644
--- a/src/parser.yy
+++ b/src/parser.yy
@@ -265,6 +265,7 @@ stmt : expr                { $$ = new ast::ExprStatement($1); }
      | jump_stmt           { $$ = $1; }
      | map "=" expr        { $$ = new ast::AssignMapStatement($1, $3, @2); }
      | var "=" expr        { $$ = new ast::AssignVarStatement($1, $3, @2); }
+     | tuple_assignment
      ;
 
 compound_assignment : map LEFTASSIGN expr  { $$ = new ast::AssignMapStatement($1, new ast::Binop($1, token::LEFT,  $3, @2)); }
@@ -289,6 +290,8 @@ compound_assignment : map LEFTASSIGN expr  { $$ = new ast::AssignMapStatement($1
                     | var BXORASSIGN expr  { $$ = new ast::AssignVarStatement($1, new ast::Binop($1, token::BXOR,  $3, @2)); }
                     ;
 
+tuple_assignment : expr DOT INT "=" expr { error(@1 + @5, "Tuples are immutable once created. Consider creating a new tuple and assigning it instead."); YYERROR; }
+
 int : MINUS INT    { $$ = new ast::Integer(-1 * $2, @$); }
     | INT          { $$ = new ast::Integer($1, @$); }
     ;

From 6ac650b7fc6ce536312ed89d3d318c25b017ebcf Mon Sep 17 00:00:00 2001
From: Rylan Dmello <mail@rylan.coffee>
Date: Thu, 15 Oct 2020 08:51:22 -0400
Subject: [PATCH 2/4] Test for tuple assignment error

---
 tests/parser.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tests/parser.cpp b/tests/parser.cpp
index 5956f64e567c..9215b702c2dc 100644
--- a/tests/parser.cpp
+++ b/tests/parser.cpp
@@ -1663,6 +1663,20 @@ TEST(Parser, while_loop)
 )PROG");
 }
 
+TEST(Parser, tuple_assignment_error)
+{
+  BPFtrace bpftrace;
+  std::stringstream out;
+  Driver driver(bpftrace, out);
+  EXPECT_EQ(driver.parse_str("i:s:1 { @x = (1, 2); $x.1 = 1; }"), 1);
+  std::string expected =
+      R"(stdin:1:22-30: ERROR: Tuples are immutable once created. Consider creating a new tuple and assigning it instead.
+i:s:1 { @x = (1, 2); $x.1 = 1; }
+                     ~~~~~~~~
+)";
+  EXPECT_EQ(out.str(), expected);
+}
+
 } // namespace parser
 } // namespace test
 } // namespace bpftrace

From c6d8ba2a12457c24111b64751d813729c6cdf79a Mon Sep 17 00:00:00 2001
From: Rylan Dmello <mail@rylan.coffee>
Date: Thu, 15 Oct 2020 21:38:34 -0400
Subject: [PATCH 3/4] Add some more test cases for tuple assignment parse
 failure

---
 tests/parser.cpp | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/tests/parser.cpp b/tests/parser.cpp
index 9215b702c2dc..5d81ac4944d8 100644
--- a/tests/parser.cpp
+++ b/tests/parser.cpp
@@ -1663,7 +1663,7 @@ TEST(Parser, while_loop)
 )PROG");
 }
 
-TEST(Parser, tuple_assignment_error)
+TEST(Parser, tuple_assignment_error_message)
 {
   BPFtrace bpftrace;
   std::stringstream out;
@@ -1677,6 +1677,16 @@ i:s:1 { @x = (1, 2); $x.1 = 1; }
   EXPECT_EQ(out.str(), expected);
 }
 
+TEST(Parser, tuple_assignment_error)
+{
+  test_parse_failure("i:s:1 { (1, 0) = 0 }");
+  test_parse_failure("i:s:1 { ((1, 0), 3).0.0 = 3 }");
+  test_parse_failure("i:s:1 { ((1, 0), 3).0 = (0, 1) }");
+  test_parse_failure("i:s:1 { (1, \"two\", (3, 4)).5 = \"six\"; }");
+  test_parse_failure("i:s:1 { $a = 1; $a.2 = 3 }");
+  test_parse_failure("i:s:1 { 0.1 = 1.0 }");
+}
+
 } // namespace parser
 } // namespace test
 } // namespace bpftrace

From 54399caa2ccbd76370401a82664ec6084ccb0674 Mon Sep 17 00:00:00 2001
From: Rylan Dmello <mail@rylan.coffee>
Date: Thu, 15 Oct 2020 21:46:20 -0400
Subject: [PATCH 4/4] Update changelog

---
 CHANGELOG.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b5559519faa1..7ef3097075d4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -54,6 +54,8 @@ and this project adheres to
   - [#1542](https://github.com/iovisor/bpftrace/pull/1542)
 - Change a part of the message of '-v' output
   - [#1553](https://github.com/iovisor/bpftrace/pull/1553)
+- Improve tuple assignment error message
+  - [#1563](https://github.com/iovisor/bpftrace/pull/1563)
 
 #### Deprecated