Sema: fix and improve errors for `for` loop objects and non-indexables

Operands to @memcpy and @memset were being called "for loop operands" in
the error.

1 files changed, 23 insertions, 31 deletions

diff --git a/src/Sema.zig b/src/Sema.zig
index 0288ff8132..36538ba8f8 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -3401,8 +3401,8 @@ fn indexablePtrLen(
 ) CompileError!Air.Inst.Ref {
     const object_ty = sema.typeOf(object);
     const is_pointer_to = object_ty.isSinglePointer();
-    const array_ty = if (is_pointer_to) object_ty.childType() else object_ty;
-    try checkIndexable(sema, block, src, array_ty);
+    const indexable_ty = if (is_pointer_to) object_ty.childType() else object_ty;
+    try checkIndexable(sema, block, src, indexable_ty);
     return sema.fieldVal(block, src, object, "len", src);
 }
 
@@ -3413,7 +3413,7 @@ fn indexablePtrLenOrNone(
     object: Air.Inst.Ref,
 ) CompileError!Air.Inst.Ref {
     const object_ty = sema.typeOf(object);
-    const array_ty = t: {
+    const indexable_ty = t: {
         const ptr_size = object_ty.ptrSizeOrNull() orelse break :t object_ty;
         break :t switch (ptr_size) {
             .Many => return .none,
@@ -3421,7 +3421,7 @@ fn indexablePtrLenOrNone(
             else => object_ty,
         };
     };
-    try checkIndexable(sema, block, src, array_ty);
+    try checkIndexable(sema, block, src, indexable_ty);
     return sema.fieldVal(block, src, object, "len", src);
 }
 
@@ -3991,7 +3991,16 @@ fn zirForLen(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air.
             .input_index = i,
         } };
         const arg_len_uncoerced = if (is_int) object else l: {
-            try checkIndexable(sema, block, arg_src, object_ty);
+            if (!object_ty.isIndexable()) {
+                // Instead of using checkIndexable we customize this error.
+                const msg = msg: {
+                    const msg = try sema.errMsg(block, arg_src, "type '{}' is not indexable and not a range", .{object_ty.fmt(sema.mod)});
+                    errdefer msg.destroy(sema.gpa);
+                    try sema.errNote(block, arg_src, msg, "for loop operand must be a range, array, slice, tuple, or vector", .{});
+                    break :msg msg;
+                };
+                return sema.failWithOwnedErrorMsg(msg);
+            }
             if (!object_ty.indexableHasLen()) continue;
 
             break :l try sema.fieldVal(block, arg_src, object, "len", arg_src);
@@ -24767,9 +24776,7 @@ fn elemPtr(
         .Pointer => indexable_ptr_ty.elemType(),
         else => return sema.fail(block, indexable_ptr_src, "expected pointer, found '{}'", .{indexable_ptr_ty.fmt(sema.mod)}),
     };
-    if (!indexable_ty.isIndexable()) {
-        return sema.fail(block, src, "element access of non-indexable type '{}'", .{indexable_ty.fmt(sema.mod)});
-    }
+    try checkIndexable(sema, block, src, indexable_ty);
 
     switch (indexable_ty.zigTypeTag()) {
         .Array, .Vector => return sema.elemPtrArray(block, src, indexable_ptr_src, indexable_ptr, elem_index_src, elem_index, init, oob_safety),
@@ -24801,9 +24808,7 @@ fn elemPtrOneLayerOnly(
     const indexable_ty = sema.typeOf(indexable);
     const target = sema.mod.getTarget();
 
-    if (!indexable_ty.isIndexable()) {
-        return sema.fail(block, src, "element access of non-indexable type '{}'", .{indexable_ty.fmt(sema.mod)});
-    }
+    try checkIndexable(sema, block, src, indexable_ty);
 
     switch (indexable_ty.ptrSize()) {
         .Slice => return sema.elemPtrSlice(block, src, indexable_src, indexable, elem_index_src, elem_index, oob_safety),
@@ -24824,7 +24829,7 @@ fn elemPtrOneLayerOnly(
             return block.addPtrElemPtr(indexable, elem_index, result_ty);
         },
         .One => {
-            assert(indexable_ty.childType().zigTypeTag() == .Array); // Guaranteed by isIndexable
+            assert(indexable_ty.childType().zigTypeTag() == .Array); // Guaranteed by checkIndexable
             return sema.elemPtrArray(block, src, indexable_src, indexable, elem_index_src, elem_index, init, oob_safety);
         },
     }
@@ -24843,9 +24848,7 @@ fn elemVal(
     const indexable_ty = sema.typeOf(indexable);
     const target = sema.mod.getTarget();
 
-    if (!indexable_ty.isIndexable()) {
-        return sema.fail(block, src, "element access of non-indexable type '{}'", .{indexable_ty.fmt(sema.mod)});
-    }
+    try checkIndexable(sema, block, src, indexable_ty);
 
     // TODO in case of a vector of pointers, we need to detect whether the element
     // index is a scalar or vector instead of unconditionally casting to usize.
@@ -24873,7 +24876,7 @@ fn elemVal(
                 return block.addBinOp(.ptr_elem_val, indexable, elem_index);
             },
             .One => {
-                assert(indexable_ty.childType().zigTypeTag() == .Array); // Guaranteed by isIndexable
+                assert(indexable_ty.childType().zigTypeTag() == .Array); // Guaranteed by checkIndexable
                 const elem_ptr = try sema.elemPtr(block, indexable_src, indexable, elem_index, elem_index_src, false, oob_safety);
                 return sema.analyzeLoad(block, indexable_src, elem_ptr, elem_index_src);
             },
@@ -30997,23 +31000,12 @@ fn checkBackingIntType(sema: *Sema, block: *Block, src: LazySrcLoc, backing_int_
     }
 }
 
-fn checkIndexable(sema: *Sema, block: *Block, src: LazySrcLoc, array_ty: Type) !void {
-    if (!array_ty.isIndexable()) {
+fn checkIndexable(sema: *Sema, block: *Block, src: LazySrcLoc, ty: Type) !void {
+    if (!ty.isIndexable()) {
         const msg = msg: {
-            const msg = try sema.errMsg(
-                block,
-                src,
-                "type '{}' does not support indexing",
-                .{array_ty.fmt(sema.mod)},
-            );
+            const msg = try sema.errMsg(block, src, "type '{}' does not support indexing", .{ty.fmt(sema.mod)});
             errdefer msg.destroy(sema.gpa);
-            try sema.errNote(
-                block,
-                src,
-                msg,
-                "for loop operand must be an array, slice, tuple, or vector",
-                .{},
-            );
+            try sema.errNote(block, src, msg, "operand must be an array, slice, tuple, or vector", .{});
             break :msg msg;
         };
         return sema.failWithOwnedErrorMsg(msg);