From cd74cdfdaf5157704b836c8de1c32b5a03dddcae Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Tue, 8 Aug 2023 14:57:25 +0100
Subject: [PATCH] Remove `switch in` in favour of `switch _ in`

---
 core/net/addr.odin           | 4 ++--
 core/net/dns.odin            | 6 +++---
 core/odin/ast/clone.odin     | 2 +-
 core/odin/parser/parser.odin | 2 +-
 examples/demo/demo.odin      | 4 ++--
 src/parser.cpp               | 5 ++++-
 6 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/core/net/addr.odin b/core/net/addr.odin
index e6b503aaf..be04be15e 100644
--- a/core/net/addr.odin
+++ b/core/net/addr.odin
@@ -471,7 +471,7 @@ join_port :: proc(address_or_host: string, port: int, allocator := context.alloc
 		// hostname
 		fmt.sbprintf(&b, "%v:%v", addr_or_host, port)
 	} else {
-		switch in addr {
+		switch _ in addr {
 		case IP4_Address:
 			fmt.sbprintf(&b, "%v:%v", address_to_string(addr), port)
 		case IP6_Address:
@@ -606,7 +606,7 @@ to_string :: proc{address_to_string, endpoint_to_string}
 
 
 family_from_address :: proc(addr: Address) -> Address_Family {
-	switch in addr {
+	switch _ in addr {
 	case IP4_Address: return .IP4
 	case IP6_Address: return .IP6
 	case:
diff --git a/core/net/dns.odin b/core/net/dns.odin
index 6afa844fe..27713d790 100644
--- a/core/net/dns.odin
+++ b/core/net/dns.odin
@@ -96,7 +96,7 @@ resolve :: proc(hostname_and_maybe_port: string) -> (ep4, ep6: Endpoint, err: Ne
 	switch t in target {
 	case Endpoint:
 		// NOTE(tetra): The hostname was actually an IP address; nothing to resolve, so just return it.
-		switch in t.address {
+		switch _ in t.address {
 		case IP4_Address: ep4 = t
 		case IP6_Address: ep6 = t
 		case:             unreachable()
@@ -122,7 +122,7 @@ resolve_ip4 :: proc(hostname_and_maybe_port: string) -> (ep4: Endpoint, err: Net
 	switch t in target {
 	case Endpoint:
 		// NOTE(tetra): The hostname was actually an IP address; nothing to resolve, so just return it.
-		switch in t.address {
+		switch _ in t.address {
 		case IP4_Address:
 			return t, nil
 		case IP6_Address:
@@ -149,7 +149,7 @@ resolve_ip6 :: proc(hostname_and_maybe_port: string) -> (ep6: Endpoint, err: Net
 	switch t in target {
 	case Endpoint:
 		// NOTE(tetra): The hostname was actually an IP address; nothing to resolve, so just return it.
-		switch in t.address {
+		switch _ in t.address {
 		case IP4_Address:
 			err = .Unable_To_Resolve
 			return
diff --git a/core/odin/ast/clone.odin b/core/odin/ast/clone.odin
index b8c0b8087..407ddf2cc 100644
--- a/core/odin/ast/clone.odin
+++ b/core/odin/ast/clone.odin
@@ -77,7 +77,7 @@ clone_node :: proc(node: ^Node) -> ^Node {
 		align = elem.align
 	}
 
-	#partial switch in node.derived {
+	#partial switch _ in node.derived {
 	case ^Package, ^File:
 		panic("Cannot clone this node type")
 	}
diff --git a/core/odin/parser/parser.odin b/core/odin/parser/parser.odin
index 32154aff7..122e73b9c 100644
--- a/core/odin/parser/parser.odin
+++ b/core/odin/parser/parser.odin
@@ -1091,7 +1091,7 @@ parse_attribute :: proc(p: ^Parser, tok: tokenizer.Token, open_kind, close_kind:
 
 parse_foreign_block_decl :: proc(p: ^Parser) -> ^ast.Stmt {
 	decl := parse_stmt(p)
-	#partial switch in decl.derived_stmt {
+	#partial switch _ in decl.derived_stmt {
 	case ^ast.Empty_Stmt, ^ast.Bad_Stmt, ^ast.Bad_Decl:
 		// Ignore
 		return nil
diff --git a/examples/demo/demo.odin b/examples/demo/demo.odin
index e9e0a8d63..94aafe8b2 100644
--- a/examples/demo/demo.odin
+++ b/examples/demo/demo.odin
@@ -1354,13 +1354,13 @@ partial_switch :: proc() {
 	{ // union
 		Foo :: union {int, bool}
 		f: Foo = 123
-		switch in f {
+		switch _ in f {
 		case int:  fmt.println("int")
 		case bool: fmt.println("bool")
 		case:
 		}
 
-		#partial switch in f {
+		#partial switch _ in f {
 		case bool: fmt.println("bool")
 		}
 	}
diff --git a/src/parser.cpp b/src/parser.cpp
index bfbd7b32a..a2de85d84 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -4382,7 +4382,10 @@ gb_internal Ast *parse_switch_stmt(AstFile *f) {
 		f->expr_level = -1;
 		defer (f->expr_level = prev_level);
 
-		if (allow_token(f, Token_in)) {
+		if (f->curr_token.kind == Token_in) {
+			Token in_token = expect_token(f, Token_in);
+			syntax_error(in_token, "Prefer 'switch _ in' over 'switch in'");
+
 			auto lhs = array_make<Ast *>(heap_allocator(), 0, 1);
 			auto rhs = array_make<Ast *>(heap_allocator(), 0, 1);
 			Token blank_ident = token;