first pass at zig build system

 * `zig build --export [obj|lib|exe]` changed to `zig build_obj`,
   `zig build_lib` and `zig build_exe` respectively.
 * `--name` parameter is optional when it can be inferred from the
   root source filename. closes #207
 * `zig build` now looks for `build.zig` which interacts with
   `std.build.Builder` to describe the targets, and then the zig
   build system prints TODO: build these targets. See #204
 * add `@bitcast` which is mainly used for pointer reinterpret
   casting and make explicit casting not do pointer reinterpretation.
   Closes #290
 * fix debug info for byval parameters
 * sort command line help options
 * `std.debug.panic` supports format string printing
 * add `std.mem.IncrementingAllocator`
 * fix const ptr to a variable with data changing at runtime.
   closes #289

1 files changed, 59 insertions, 0 deletions

diff --git a/std/build.zig b/std/build.zig
new file mode 100644
index 0000000000..746800668a
--- /dev/null
+++ b/std/build.zig
@@ -0,0 +1,59 @@
+const io = @import("io.zig");
+const mem = @import("mem.zig");
+const debug = @import("debug.zig");
+const List = @import("list.zig").List;
+const Allocator = @import("mem.zig").Allocator;
+
+error ExtraArg;
+
+pub const Builder = struct {
+    zig_exe: []const u8,
+    allocator: &Allocator,
+    exe_list: List(&Exe),
+
+    pub fn init(zig_exe: []const u8, allocator: &Allocator) -> Builder {
+        Builder {
+            .zig_exe = zig_exe,
+            .allocator = allocator,
+            .exe_list = List(&Exe).init(allocator),
+        }
+    }
+
+    pub fn addExe(self: &Builder, root_src: []const u8, name: []const u8) -> &Exe {
+        return self.addExeErr(root_src, name) %% |err| handleErr(err);
+    }
+
+    pub fn addExeErr(self: &Builder, root_src: []const u8, name: []const u8) -> %&Exe {
+        const exe = %return self.allocator.create(Exe);
+        *exe = Exe {
+            .root_src = root_src,
+            .name = name,
+        };
+        %return self.exe_list.append(exe);
+        return exe;
+    }
+
+    pub fn make(self: &Builder, args: []const []const u8) -> %void {
+        var verbose = false;
+        for (args) |arg| {
+            if (mem.eql(u8, arg, "--verbose")) {
+                verbose = true;
+            } else {
+                %%io.stderr.printf("Unrecognized argument: '{}'\n", arg);
+                return error.ExtraArg;
+            }
+        }
+        for (self.exe_list.toSlice()) |exe| {
+            %%io.stderr.printf("TODO: invoke this command:\nzig build_exe {} --name {}\n", exe.root_src, exe.name);
+        }
+    }
+};
+
+const Exe = struct {
+    root_src: []const u8,
+    name: []const u8,
+};
+
+fn handleErr(err: error) -> noreturn {
+    debug.panic("error: {}\n", @errorName(err));
+}