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remove unreachable code paths from std.zig.Ast.lastToken
This function checks for various possibilities that are never produced by the parser. Given that lastToken is unsafe to call on an Ast with errors, I also removed code paths that would be reachable on an Ast with errors.
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+15
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‎lib/std/zig/Ast.zig

Lines changed: 15 additions & 132 deletions
Original file line numberDiff line numberDiff line change
@@ -800,7 +800,6 @@ pub fn lastToken(tree: Ast, node: Node.Index) TokenIndex {
800800
const tags = tree.nodes.items(.tag);
801801
const datas = tree.nodes.items(.data);
802802
const main_tokens = tree.nodes.items(.main_token);
803-
const token_starts = tree.tokens.items(.start);
804803
const token_tags = tree.tokens.items(.tag);
805804
var n = node;
806805
var end_offset: TokenIndex = 0;
@@ -816,6 +815,7 @@ pub fn lastToken(tree: Ast, node: Node.Index) TokenIndex {
816815
.@"try",
817816
.@"await",
818817
.optional_type,
818+
.@"suspend",
819819
.@"resume",
820820
.@"nosuspend",
821821
.@"comptime",
@@ -880,6 +880,9 @@ pub fn lastToken(tree: Ast, node: Node.Index) TokenIndex {
880880
.for_simple,
881881
.fn_proto_simple,
882882
.fn_proto_multi,
883+
.fn_proto_one,
884+
.fn_proto,
885+
.fn_decl,
883886
.ptr_type_aligned,
884887
.ptr_type_sentinel,
885888
.ptr_type,
@@ -928,9 +931,7 @@ pub fn lastToken(tree: Ast, node: Node.Index) TokenIndex {
928931
.call, .async_call => {
929932
end_offset += 1; // for the rparen
930933
const params = tree.extraData(datas[n].rhs, Node.SubRange);
931-
if (params.end - params.start == 0) {
932-
return main_tokens[n] + end_offset;
933-
}
934+
assert(params.end - params.start > 0);
934935
n = tree.extra_data[params.end - 1]; // last parameter
935936
},
936937
.tagged_union_enum_tag => {
@@ -1122,48 +1123,28 @@ pub fn lastToken(tree: Ast, node: Node.Index) TokenIndex {
11221123
n = datas[n].rhs;
11231124
} else {
11241125
const extra = tree.extraData(datas[n].lhs, Node.LocalVarDecl);
1125-
if (extra.align_node != 0) {
1126-
end_offset += 1; // for the rparen
1127-
n = extra.align_node;
1128-
} else if (extra.type_node != 0) {
1129-
n = extra.type_node;
1130-
} else {
1131-
end_offset += 1; // from mut token to name
1132-
return main_tokens[n] + end_offset;
1133-
}
1126+
assert(extra.align_node != 0);
1127+
end_offset += 1; // for the rparen
1128+
n = extra.align_node;
11341129
}
11351130
},
11361131
.container_field_init => {
11371132
if (datas[n].rhs != 0) {
11381133
n = datas[n].rhs;
1139-
} else if (datas[n].lhs != 0) {
1140-
n = datas[n].lhs;
11411134
} else {
1142-
return main_tokens[n] + end_offset;
1135+
assert(datas[n].lhs != 0);
1136+
n = datas[n].lhs;
11431137
}
11441138
},
11451139
.container_field_align => {
1146-
if (datas[n].rhs != 0) {
1147-
end_offset += 1; // for the rparen
1148-
n = datas[n].rhs;
1149-
} else if (datas[n].lhs != 0) {
1150-
n = datas[n].lhs;
1151-
} else {
1152-
return main_tokens[n] + end_offset;
1153-
}
1140+
assert(datas[n].rhs != 0);
1141+
end_offset += 1; // for the rparen
1142+
n = datas[n].rhs;
11541143
},
11551144
.container_field => {
11561145
const extra = tree.extraData(datas[n].rhs, Node.ContainerField);
1157-
if (extra.value_expr != 0) {
1158-
n = extra.value_expr;
1159-
} else if (extra.align_expr != 0) {
1160-
end_offset += 1; // for the rparen
1161-
n = extra.align_expr;
1162-
} else if (datas[n].lhs != 0) {
1163-
n = datas[n].lhs;
1164-
} else {
1165-
return main_tokens[n] + end_offset;
1166-
}
1146+
assert(extra.value_expr != 0);
1147+
n = extra.value_expr;
11671148
},
11681149

11691150
.array_init_one,
@@ -1208,97 +1189,6 @@ pub fn lastToken(tree: Ast, node: Node.Index) TokenIndex {
12081189
return main_tokens[n] + end_offset;
12091190
}
12101191
},
1211-
.fn_decl => {
1212-
if (datas[n].rhs != 0) {
1213-
n = datas[n].rhs;
1214-
} else {
1215-
n = datas[n].lhs;
1216-
}
1217-
},
1218-
.fn_proto_one => {
1219-
const extra = tree.extraData(datas[n].lhs, Node.FnProtoOne);
1220-
// addrspace, linksection, callconv, align can appear in any order, so we
1221-
// find the last one here.
1222-
var max_node: Node.Index = datas[n].rhs;
1223-
var max_start = token_starts[main_tokens[max_node]];
1224-
var max_offset: TokenIndex = 0;
1225-
if (extra.align_expr != 0) {
1226-
const start = token_starts[main_tokens[extra.align_expr]];
1227-
if (start > max_start) {
1228-
max_node = extra.align_expr;
1229-
max_start = start;
1230-
max_offset = 1; // for the rparen
1231-
}
1232-
}
1233-
if (extra.addrspace_expr != 0) {
1234-
const start = token_starts[main_tokens[extra.addrspace_expr]];
1235-
if (start > max_start) {
1236-
max_node = extra.addrspace_expr;
1237-
max_start = start;
1238-
max_offset = 1; // for the rparen
1239-
}
1240-
}
1241-
if (extra.section_expr != 0) {
1242-
const start = token_starts[main_tokens[extra.section_expr]];
1243-
if (start > max_start) {
1244-
max_node = extra.section_expr;
1245-
max_start = start;
1246-
max_offset = 1; // for the rparen
1247-
}
1248-
}
1249-
if (extra.callconv_expr != 0) {
1250-
const start = token_starts[main_tokens[extra.callconv_expr]];
1251-
if (start > max_start) {
1252-
max_node = extra.callconv_expr;
1253-
max_start = start;
1254-
max_offset = 1; // for the rparen
1255-
}
1256-
}
1257-
n = max_node;
1258-
end_offset += max_offset;
1259-
},
1260-
.fn_proto => {
1261-
const extra = tree.extraData(datas[n].lhs, Node.FnProto);
1262-
// addrspace, linksection, callconv, align can appear in any order, so we
1263-
// find the last one here.
1264-
var max_node: Node.Index = datas[n].rhs;
1265-
var max_start = token_starts[main_tokens[max_node]];
1266-
var max_offset: TokenIndex = 0;
1267-
if (extra.align_expr != 0) {
1268-
const start = token_starts[main_tokens[extra.align_expr]];
1269-
if (start > max_start) {
1270-
max_node = extra.align_expr;
1271-
max_start = start;
1272-
max_offset = 1; // for the rparen
1273-
}
1274-
}
1275-
if (extra.addrspace_expr != 0) {
1276-
const start = token_starts[main_tokens[extra.addrspace_expr]];
1277-
if (start > max_start) {
1278-
max_node = extra.addrspace_expr;
1279-
max_start = start;
1280-
max_offset = 1; // for the rparen
1281-
}
1282-
}
1283-
if (extra.section_expr != 0) {
1284-
const start = token_starts[main_tokens[extra.section_expr]];
1285-
if (start > max_start) {
1286-
max_node = extra.section_expr;
1287-
max_start = start;
1288-
max_offset = 1; // for the rparen
1289-
}
1290-
}
1291-
if (extra.callconv_expr != 0) {
1292-
const start = token_starts[main_tokens[extra.callconv_expr]];
1293-
if (start > max_start) {
1294-
max_node = extra.callconv_expr;
1295-
max_start = start;
1296-
max_offset = 1; // for the rparen
1297-
}
1298-
}
1299-
n = max_node;
1300-
end_offset += max_offset;
1301-
},
13021192
.while_cont => {
13031193
const extra = tree.extraData(datas[n].rhs, Node.WhileCont);
13041194
assert(extra.then_expr != 0);
@@ -1318,13 +1208,6 @@ pub fn lastToken(tree: Ast, node: Node.Index) TokenIndex {
13181208
const extra = @as(Node.For, @bitCast(datas[n].rhs));
13191209
n = tree.extra_data[datas[n].lhs + extra.inputs + @intFromBool(extra.has_else)];
13201210
},
1321-
.@"suspend" => {
1322-
if (datas[n].lhs != 0) {
1323-
n = datas[n].lhs;
1324-
} else {
1325-
return main_tokens[n] + end_offset;
1326-
}
1327-
},
13281211
.array_type_sentinel => {
13291212
const extra = tree.extraData(datas[n].rhs, Node.ArrayTypeSentinel);
13301213
n = extra.elem_type;

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