rework std.Io.Writer.Allocating to support runtime-known alignment

Also, breaking API changes to:
* std.fs.Dir.readFileAlloc
* std.fs.Dir.readFileAllocOptions

3 files changed, 7 insertions, 8 deletions

diff --git a/lib/std/Build/Step/CheckFile.zig b/lib/std/Build/Step/CheckFile.zig
index 699e6d2e9d..5e664b3bc3 100644
--- a/lib/std/Build/Step/CheckFile.zig
+++ b/lib/std/Build/Step/CheckFile.zig
@@ -53,7 +53,7 @@ fn make(step: *Step, options: Step.MakeOptions) !void {
     try step.singleUnchangingWatchInput(check_file.source);
 
     const src_path = check_file.source.getPath2(b, step);
-    const contents = fs.cwd().readFileAlloc(b.allocator, src_path, check_file.max_bytes) catch |err| {
+    const contents = fs.cwd().readFileAlloc(src_path, b.allocator, .limited(check_file.max_bytes)) catch |err| {
         return step.fail("unable to read '{s}': {s}", .{
             src_path, @errorName(err),
         });
diff --git a/lib/std/Build/Step/CheckObject.zig b/lib/std/Build/Step/CheckObject.zig
index 5fa039b772..2f7afa8dba 100644
--- a/lib/std/Build/Step/CheckObject.zig
+++ b/lib/std/Build/Step/CheckObject.zig
@@ -553,14 +553,13 @@ fn make(step: *Step, make_options: Step.MakeOptions) !void {
 
     const src_path = check_object.source.getPath3(b, step);
     const contents = src_path.root_dir.handle.readFileAllocOptions(
-        gpa,
         src_path.sub_path,
-        check_object.max_bytes,
-        null,
+        gpa,
+        .limited(check_object.max_bytes),
         .of(u64),
         null,
-    ) catch |err| return step.fail("unable to read '{f}': {s}", .{
-        std.fmt.alt(src_path, .formatEscapeChar), @errorName(err),
+    ) catch |err| return step.fail("unable to read '{f}': {t}", .{
+        std.fmt.alt(src_path, .formatEscapeChar), err,
     });
 
     var vars: std.StringHashMap(u64) = .init(gpa);
diff --git a/lib/std/Build/Step/ConfigHeader.zig b/lib/std/Build/Step/ConfigHeader.zig
index 3c7f9a70c2..3f89bf8ec9 100644
--- a/lib/std/Build/Step/ConfigHeader.zig
+++ b/lib/std/Build/Step/ConfigHeader.zig
@@ -208,7 +208,7 @@ fn make(step: *Step, options: Step.MakeOptions) !void {
         .autoconf_undef, .autoconf_at => |file_source| {
             try bw.writeAll(c_generated_line);
             const src_path = file_source.getPath2(b, step);
-            const contents = std.fs.cwd().readFileAlloc(arena, src_path, config_header.max_bytes) catch |err| {
+            const contents = std.fs.cwd().readFileAlloc(src_path, arena, .limited(config_header.max_bytes)) catch |err| {
                 return step.fail("unable to read autoconf input file '{s}': {s}", .{
                     src_path, @errorName(err),
                 });
@@ -222,7 +222,7 @@ fn make(step: *Step, options: Step.MakeOptions) !void {
         .cmake => |file_source| {
             try bw.writeAll(c_generated_line);
             const src_path = file_source.getPath2(b, step);
-            const contents = std.fs.cwd().readFileAlloc(arena, src_path, config_header.max_bytes) catch |err| {
+            const contents = std.fs.cwd().readFileAlloc(src_path, arena, .limited(config_header.max_bytes)) catch |err| {
                 return step.fail("unable to read cmake input file '{s}': {s}", .{
                     src_path, @errorName(err),
                 });