Require elements in 1-to-n assignments to match targets exactly

Makefile

@@ -28,7 +28,7 @@ static ?=       ## Enable static linking
 O := .build
 SOURCES := $(shell find src -name '*.cr')
 SPEC_SOURCES := $(shell find spec -name '*.cr')
-override FLAGS += $(if $(release),--release )$(if $(stats),--stats )$(if $(progress),--progress )$(if $(threads),--threads $(threads) )$(if $(debug),-d )$(if $(static),--static )$(if $(LDFLAGS),--link-flags="$(LDFLAGS)" )$(if $(target),--cross-compile --target $(target) )
+override FLAGS += -D preview_multi_assign $(if $(release),--release )$(if $(stats),--stats )$(if $(progress),--progress )$(if $(threads),--threads $(threads) )$(if $(debug),-d )$(if $(static),--static )$(if $(LDFLAGS),--link-flags="$(LDFLAGS)" )$(if $(target),--cross-compile --target $(target) )
 SPEC_WARNINGS_OFF := --exclude-warnings spec/std --exclude-warnings spec/compiler
 SPEC_FLAGS := $(if $(verbose),-v )$(if $(junit_output),--junit_output $(junit_output) )
 CRYSTAL_CONFIG_LIBRARY_PATH := '$$ORIGIN/../lib/crystal'

spec/compiler/codegen/multi_assign_spec.cr

@@ -21,6 +21,38 @@ describe "Code gen: multi assign" do
       CR
   end
 
+  context "without preview_multi_assign" do
+    it "doesn't raise if value size in 1 to n assignment doesn't match target count" do
+      run(<<-CR).to_i.should eq(4)
+        require "prelude"
+
+        begin
+          a, b = [1, 2, 3]
+          4
+        rescue ex : Exception
+          raise ex unless ex.message == "Multiple assignment count mismatch"
+          5
+        end
+        CR
+    end
+  end
+
+  context "preview_multi_assign" do
+    it "raises if value size in 1 to n assignment doesn't match target count" do
+      run(<<-CR, flags: %w(preview_multi_assign)).to_i.should eq(5)
+        require "prelude"
+
+        begin
+          a, b = [1, 2, 3]
+          4
+        rescue ex : Exception
+          raise ex unless ex.message == "Multiple assignment count mismatch"
+          5
+        end
+        CR
+    end
+  end
+
   it "supports m to n assignment, with splat on left-hand side (1)" do
     run(<<-CR).to_i.should eq(12345)
       #{tuple_new}

spec/compiler/normalize/multi_assign_spec.cr

@@ -12,15 +12,6 @@ describe "Normalize: multi assign" do
       CR
   end
 
-  it "normalizes 1 to n" do
-    assert_expand_second "d = 1; a, b, c = d", <<-CR
-      __temp_1 = d
-      a = __temp_1[0]
-      b = __temp_1[1]
-      c = __temp_1[2]
-      CR
-  end
-
   it "normalizes n to n with []" do
     assert_expand_third "a = 1; b = 2; a[0], b[1] = 2, 3", <<-CR
       __temp_1 = 2
@@ -30,14 +21,6 @@ describe "Normalize: multi assign" do
       CR
   end
 
-  it "normalizes 1 to n with []" do
-    assert_expand_third "a = 1; b = 2; a[0], b[1] = 2", <<-CR
-      __temp_1 = 2
-      a[0] = __temp_1[0]
-      b[1] = __temp_1[1]
-      CR
-  end
-
   it "normalizes n to n with call" do
     assert_expand_third "a = 1; b = 2; a.foo, b.bar = 2, 3", <<-CR
       __temp_1 = 2
@@ -47,12 +30,67 @@ describe "Normalize: multi assign" do
       CR
   end
 
-  it "normalizes 1 to n with call" do
-    assert_expand_third "a = 1; b = 2; a.foo, b.bar = 2", <<-CR
-      __temp_1 = 2
-      a.foo = __temp_1[0]
-      b.bar = __temp_1[1]
-      CR
+  context "without preview_multi_assign" do
+    it "normalizes 1 to n" do
+      assert_expand_second "d = 1; a, b, c = d", <<-CR
+        __temp_1 = d
+        a = __temp_1[0]
+        b = __temp_1[1]
+        c = __temp_1[2]
+        CR
+    end
+
+    it "normalizes 1 to n with []" do
+      assert_expand_third "a = 1; b = 2; a[0], b[1] = 2", <<-CR
+        __temp_1 = 2
+        a[0] = __temp_1[0]
+        b[1] = __temp_1[1]
+        CR
+    end
+
+    it "normalizes 1 to n with call" do
+      assert_expand_third "a = 1; b = 2; a.foo, b.bar = 2", <<-CR
+        __temp_1 = 2
+        a.foo = __temp_1[0]
+        b.bar = __temp_1[1]
+        CR
+    end
+  end
+
+  context "preview_multi_assign" do
+    it "normalizes 1 to n" do
+      assert_expand_second "d = 1; a, b, c = d", <<-CR, flags: "preview_multi_assign"
+        __temp_1 = d
+        if __temp_1.size != 3
+          ::raise(::IndexError.new("Multiple assignment count mismatch"))
+        end
+        a = __temp_1[0]
+        b = __temp_1[1]
+        c = __temp_1[2]
+        CR
+    end
+
+    it "normalizes 1 to n with []" do
+      assert_expand_third "a = 1; b = 2; a[0], b[1] = 2", <<-CR, flags: "preview_multi_assign"
+        __temp_1 = 2
+        if __temp_1.size != 2
+          ::raise(::IndexError.new("Multiple assignment count mismatch"))
+        end
+        a[0] = __temp_1[0]
+        b[1] = __temp_1[1]
+        CR
+    end
+
+    it "normalizes 1 to n with call" do
+      assert_expand_third "a = 1; b = 2; a.foo, b.bar = 2", <<-CR, flags: "preview_multi_assign"
+        __temp_1 = 2
+        if __temp_1.size != 2
+          ::raise(::IndexError.new("Multiple assignment count mismatch"))
+        end
+        a.foo = __temp_1[0]
+        b.bar = __temp_1[1]
+        CR
+    end
   end
 
   it "normalizes m to n, with splat on left-hand side, splat is empty" do

spec/compiler/semantic/multi_assign_spec.cr

@@ -0,0 +1,64 @@
+require "../../spec_helper"
+
+describe "Semantic: multi assign" do
+  context "without preview_multi_assign" do
+    it "doesn't error if assigning tuple to fewer targets" do
+      assert_type(%(
+        require "prelude"
+
+        x = {1, 2, ""}
+        a, b = x
+        {a, b}
+        )) { tuple_of [int32, int32] }
+    end
+  end
+
+  context "preview_multi_assign" do
+    it "errors if assigning tuple to fewer targets" do
+      assert_error %(
+        require "prelude"
+
+        x = {1, 2, ""}
+        a, b = x
+        ), "cannot assign Tuple(Int32, Int32, String) to 2 targets", flags: "preview_multi_assign"
+    end
+
+    pending "errors if assigning tuple to more targets" do
+      assert_error %(
+        require "prelude"
+
+        x = {1}
+        a, b = x
+        ), "cannot assign Tuple(Int32) to 2 targets", flags: "preview_multi_assign"
+    end
+
+    it "errors if assigning union of tuples to fewer targets" do
+      assert_error %(
+        require "prelude"
+
+        x = true ? {1, 2, 3} : {4, 5, 6, 7}
+        a, b = x
+        ), "cannot assign (Tuple(Int32, Int32, Int32) | Tuple(Int32, Int32, Int32, Int32)) to 2 targets", flags: "preview_multi_assign"
+    end
+
+    it "doesn't error if some type in union matches target count" do
+      assert_type(%(
+        require "prelude"
+
+        x = true ? {1, "", 3} : {4, 5}
+        a, b = x
+        {a, b}
+        ), flags: "preview_multi_assign") { tuple_of [int32, union_of(int32, string)] }
+    end
+
+    it "doesn't error if some type in union has no constant size" do
+      assert_type(%(
+        require "prelude"
+
+        x = true ? {1, "", 3} : [4, 5]
+        a, b = x
+        {a, b}
+        ), flags: "preview_multi_assign") { tuple_of [int32, union_of(int32, string)] }
+    end
+  end
+end

spec/spec_helper.cr

@@ -85,28 +85,30 @@ def assert_normalize(from, to, flags = nil, *, file = __FILE__, line = __LINE__)
   to_nodes
 end
 
-def assert_expand(from : String, to, *, file = __FILE__, line = __LINE__)
-  assert_expand Parser.parse(from), to, file: file, line: line
+def assert_expand(from : String, to, *, flags = nil, file = __FILE__, line = __LINE__)
+  assert_expand Parser.parse(from), to, flags: flags, file: file, line: line
 end
 
-def assert_expand(from_nodes : ASTNode, to, *, file = __FILE__, line = __LINE__)
-  to_nodes = LiteralExpander.new(new_program).expand(from_nodes)
+def assert_expand(from_nodes : ASTNode, to, *, flags = nil, file = __FILE__, line = __LINE__)
+  program = new_program
+  program.flags.concat(flags.split) if flags
+  to_nodes = LiteralExpander.new(program).expand(from_nodes)
   to_nodes.to_s.strip.should eq(to.strip), file: file, line: line
 end
 
-def assert_expand_second(from : String, to, *, file = __FILE__, line = __LINE__)
+def assert_expand_second(from : String, to, *, flags = nil, file = __FILE__, line = __LINE__)
   node = (Parser.parse(from).as(Expressions))[1]
-  assert_expand node, to, file: file, line: line
+  assert_expand node, to, flags: flags, file: file, line: line
 end
 
-def assert_expand_third(from : String, to, *, file = __FILE__, line = __LINE__)
+def assert_expand_third(from : String, to, *, flags = nil, file = __FILE__, line = __LINE__)
   node = (Parser.parse(from).as(Expressions))[2]
-  assert_expand node, to, file: file, line: line
+  assert_expand node, to, flags: flags, file: file, line: line
 end
 
-def assert_error(str, message = nil, *, inject_primitives = false, file = __FILE__, line = __LINE__)
+def assert_error(str, message = nil, *, inject_primitives = false, flags = nil, file = __FILE__, line = __LINE__)
   expect_raises TypeException, message, file, line do
-    semantic str, inject_primitives: inject_primitives
+    semantic str, inject_primitives: inject_primitives, flags: flags
   end
 end
 

spec/std/kernel_spec.cr

@@ -3,20 +3,20 @@ require "./spec_helper"
 
 describe "exit" do
   it "exits normally with status 0" do
-    status, _ = compile_and_run_source "exit"
+    status, _, _ = compile_and_run_source "exit"
     status.success?.should be_true
   end
 
   it "exits with given error code" do
-    status, _ = compile_and_run_source "exit 42"
+    status, _, _ = compile_and_run_source "exit 42"
     status.success?.should be_false
     status.exit_code.should eq(42)
   end
 end
 
 describe "at_exit" do
   it "runs handlers on normal program ending" do
-    status, output = compile_and_run_source <<-CODE
+    status, output, _ = compile_and_run_source <<-CODE
       at_exit do
         puts "handler code"
       end
@@ -27,7 +27,7 @@ describe "at_exit" do
   end
 
   it "runs handlers on explicit program ending" do
-    status, output = compile_and_run_source <<-'CODE'
+    status, output, _ = compile_and_run_source <<-'CODE'
       at_exit do |exit_code|
         puts "handler code, exit code: #{exit_code}"
       end
@@ -40,7 +40,7 @@ describe "at_exit" do
   end
 
   it "runs handlers in reverse order" do
-    status, output = compile_and_run_source <<-CODE
+    status, output, _ = compile_and_run_source <<-CODE
       at_exit do
         puts "first handler code"
       end
@@ -59,7 +59,7 @@ describe "at_exit" do
   end
 
   it "runs all handlers maximum once" do
-    status, output = compile_and_run_source <<-CODE
+    status, output, _ = compile_and_run_source <<-CODE
       at_exit do
         puts "first handler code"
       end
@@ -86,7 +86,7 @@ describe "at_exit" do
   end
 
   it "allows handlers to change the exit code with explicit `exit` call" do
-    status, output = compile_and_run_source <<-'CODE'
+    status, output, _ = compile_and_run_source <<-'CODE'
       at_exit do |exit_code|
         puts "first handler code, exit code: #{exit_code}"
       end
@@ -114,7 +114,7 @@ describe "at_exit" do
   end
 
   it "allows handlers to change the exit code with explicit `exit` call (2)" do
-    status, output = compile_and_run_source <<-'CODE'
+    status, output, _ = compile_and_run_source <<-'CODE'
       at_exit do |exit_code|
         puts "first handler code, exit code: #{exit_code}"
       end
@@ -210,7 +210,7 @@ describe "at_exit" do
   end
 
   it "allows at_exit inside at_exit" do
-    status, output = compile_and_run_source <<-CODE
+    status, output, _ = compile_and_run_source <<-CODE
       at_exit do
         puts "1"
         at_exit do

spec/std/process_spec.cr

@@ -165,7 +165,7 @@ describe Process do
   end
 
   pending_win32 "chroot raises when unprivileged" do
-    status, output = compile_and_run_source <<-'CODE'
+    status, output, _ = compile_and_run_source <<-'CODE'
       begin
         Process.chroot("/usr")
         puts "FAIL"

src/compiler/crystal/codegen/primitives.cr

@@ -1136,8 +1136,8 @@ class Crystal::CodeGenVisitor
     success_ordering = atomic_ordering_from_symbol_literal(call.args[-2])
     failure_ordering = atomic_ordering_from_symbol_literal(call.args[-1])
 
-    pointer, cmp, new = call_args
-    value = builder.cmpxchg(pointer, cmp, new, success_ordering, failure_ordering)
+    ptr, cmp, new, _, _ = call_args
+    value = builder.cmpxchg(ptr, cmp, new, success_ordering, failure_ordering)
     value_ptr = alloca llvm_type(node.type)
     store extract_value(value, 0), gep(value_ptr, 0, 0)
     store extract_value(value, 1), gep(value_ptr, 0, 1)
@@ -1150,8 +1150,8 @@ class Crystal::CodeGenVisitor
     ordering = atomic_ordering_from_symbol_literal(call.args[-2])
     singlethread = bool_from_bool_literal(call.args[-1])
 
-    _, pointer, val = call_args
-    builder.atomicrmw(op, pointer, val, ordering, singlethread)
+    _, ptr, val, _, _ = call_args
+    builder.atomicrmw(op, ptr, val, ordering, singlethread)
   end
 
   def codegen_primitive_fence(call, node, target_def, call_args)
@@ -1168,7 +1168,7 @@ class Crystal::CodeGenVisitor
     ordering = atomic_ordering_from_symbol_literal(call.args[-2])
     volatile = bool_from_bool_literal(call.args[-1])
 
-    ptr = call_args.first
+    ptr, _, _ = call_args
 
     inst = builder.load(ptr)
     inst.ordering = ordering
@@ -1182,7 +1182,7 @@ class Crystal::CodeGenVisitor
     ordering = atomic_ordering_from_symbol_literal(call.args[-2])
     volatile = bool_from_bool_literal(call.args[-1])
 
-    ptr, value = call_args
+    ptr, value, _, _ = call_args
 
     inst = builder.store(value, ptr)
     inst.ordering = ordering