From 759d1d9aeffbe1c5eaf7d5675b6d1c165757cdf1 Mon Sep 17 00:00:00 2001
From: Jacob G-W <jacoblevgw@gmail.com>
Date: Wed, 14 Jul 2021 18:03:15 -0400
Subject: [PATCH] astgen: errors for shadowing in loop captures

---
 src/AstGen.zig |  8 +++++++-
 test/cases.zig | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/src/AstGen.zig b/src/AstGen.zig
index f62a8f18ab..e30f3a272c 100644
--- a/src/AstGen.zig
+++ b/src/AstGen.zig
@@ -5264,7 +5264,9 @@ fn whileExpr(
                 const ident_token = if (payload_is_ref) payload_token + 1 else payload_token;
                 if (mem.eql(u8, "_", tree.tokenSlice(ident_token)))
                     break :s &then_scope.base;
-                const ident_name = try astgen.identAsString(payload_token + @boolToInt(payload_is_ref));
+                const payload_name_loc = payload_token + @boolToInt(payload_is_ref);
+                const ident_name = try astgen.identAsString(payload_name_loc);
+                try astgen.detectLocalShadowing(&then_scope.base, ident_name, payload_name_loc);
                 payload_val_scope = .{
                     .parent = &then_scope.base,
                     .gen_zir = &then_scope,
@@ -5287,6 +5289,7 @@ fn whileExpr(
             const ident_name = try astgen.identAsString(ident_token);
             if (mem.eql(u8, "_", tree.tokenSlice(ident_token)))
                 break :s &then_scope.base;
+            try astgen.detectLocalShadowing(&then_scope.base, ident_name, ident_token);
             payload_val_scope = .{
                 .parent = &then_scope.base,
                 .gen_zir = &then_scope,
@@ -5344,6 +5347,7 @@ fn whileExpr(
                 const ident_name = try astgen.identAsString(error_token);
                 if (mem.eql(u8, tree.tokenSlice(error_token), "_"))
                     break :s &else_scope.base;
+                try astgen.detectLocalShadowing(&else_scope.base, ident_name, error_token);
                 payload_val_scope = .{
                     .parent = &else_scope.base,
                     .gen_zir = &else_scope,
@@ -5483,6 +5487,7 @@ fn forExpr(
             const name_str_index = try astgen.identAsString(ident);
             const tag: Zir.Inst.Tag = if (is_ptr) .elem_ptr else .elem_val;
             const payload_inst = try then_scope.addBin(tag, array_ptr, index);
+            try astgen.detectLocalShadowing(&then_scope.base, name_str_index, ident);
             payload_val_scope = .{
                 .parent = &then_scope.base,
                 .gen_zir = &then_scope,
@@ -5506,6 +5511,7 @@ fn forExpr(
             return astgen.failTok(index_token, "discard of index capture; omit it instead", .{});
         }
         const index_name = try astgen.identAsString(index_token);
+        try astgen.detectLocalShadowing(payload_sub_scope, index_name, index_token);
         index_scope = .{
             .parent = payload_sub_scope,
             .gen_zir = &then_scope,
diff --git a/test/cases.zig b/test/cases.zig
index fe1579be44..f5eb566816 100644
--- a/test/cases.zig
+++ b/test/cases.zig
@@ -1065,6 +1065,49 @@ pub fn addCases(ctx: *TestContext) !void {
             ":5:19: error: redeclaration of local constant 'c'",
             ":4:19: note: previous declaration here",
         });
+        case.addError(
+            \\pub fn main() void {
+            \\    var i = 0;
+            \\    for (n) |_, i| {
+            \\    }
+            \\}
+        , &[_][]const u8{
+            ":3:17: error: redeclaration of local variable 'i'",
+            ":2:9: note: previous declaration here",
+        });
+        case.addError(
+            \\pub fn main() void {
+            \\    var i = 0;
+            \\    for (n) |i| {
+            \\    }
+            \\}
+        , &[_][]const u8{
+            ":3:14: error: redeclaration of local variable 'i'",
+            ":2:9: note: previous declaration here",
+        });
+        case.addError(
+            \\pub fn main() void {
+            \\    var i = 0;
+            \\    while (n) |i| {
+            \\    }
+            \\}
+        , &[_][]const u8{
+            ":3:16: error: redeclaration of local variable 'i'",
+            ":2:9: note: previous declaration here",
+        });
+        case.addError(
+            \\pub fn main() void {
+            \\    var i = 0;
+            \\    while (n) |bruh| {
+            \\        _ = bruh;
+            \\    } else |i| {
+            \\
+            \\    }
+            \\}
+        , &[_][]const u8{
+            ":5:13: error: redeclaration of local variable 'i'",
+            ":2:9: note: previous declaration here",
+        });
     }
 
     {