zig

commit a0ad2dee6a0b3bb7fd04032f6113206f7b4e73eb (tree)
parent 5c49a137d5948310d8abbf9d6f1fb899e7122239
Author: Jay Petacat <jay@jayschwa.net>
Date:   Mon,  4 Jan 2021 23:48:34 -0500

builtin: Add zig_version

This will enable code to perform version checks and make it easier to
support multiple versions of Zig.

Within the SemVer implementation, an intermediate value needed to be
coerced to a slice to workaround a comptime bug.

Closes #6466

Diffstat:
M
lib/std/SemanticVersion.zig
 | 
11
++++++++++-
M
src/Compilation.zig
 | 
6
++++++

2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/lib/std/SemanticVersion.zig b/lib/std/SemanticVersion.zig
@@ -102,7 +102,7 @@ pub fn parse(text: []const u8) !Version {
     if (extra_index == null) return ver;
 
     // Slice optional pre-release or build metadata components.
-    const extra = text[extra_index.?..text.len];
+    const extra: []const u8 = text[extra_index.?..text.len];
     if (extra[0] == '-') {
         const build_index = std.mem.indexOfScalar(u8, extra, '+');
         ver.pre = extra[1..(build_index orelse extra.len)];
@@ -293,3 +293,12 @@ fn testFmt(expected: []const u8, comptime template: []const u8, args: anytype) !
     std.debug.warn("\n======================================\n", .{});
     return error.TestFailed;
 }
+
+test "zig_version" {
+    // An approximate Zig build that predates this test.
+    const older_version = .{ .major = 0, .minor = 8, .patch = 0, .pre = "dev.874" };
+
+    // Simulated compatibility check using Zig version.
+    const compatible = comptime @import("builtin").zig_version.order(older_version) == .gt;
+    if (!compatible) @compileError("zig_version test failed");
+}
diff --git a/src/Compilation.zig b/src/Compilation.zig
@@ -2703,6 +2703,11 @@ pub fn generateBuiltinZigSource(comp: *Compilation, allocator: *Allocator) ![]u8
         \\pub const arch = Target.current.cpu.arch;
         \\/// Deprecated
         \\pub const endian = Target.current.cpu.arch.endian();
+        \\
+        \\/// Zig version. When writing code that supports multiple versions of Zig, prefer
+        \\/// feature detection (i.e. with `@hasDecl` or `@hasField`) over version checks.
+        \\pub const zig_version = try @import("std").SemanticVersion.parse("{s}");
+        \\
         \\pub const output_mode = OutputMode.{};
         \\pub const link_mode = LinkMode.{};
         \\pub const is_test = {};
@@ -2714,6 +2719,7 @@ pub fn generateBuiltinZigSource(comp: *Compilation, allocator: *Allocator) ![]u8
         \\    .features = Target.{}.featureSet(&[_]Target.{}.Feature{{
         \\
     , .{
+        build_options.version,
         std.zig.fmtId(@tagName(comp.bin_file.options.output_mode)),
         std.zig.fmtId(@tagName(comp.bin_file.options.link_mode)),
         comp.bin_file.options.is_test,