move installation logic to the build script where it belongs

* build.zig: introduce `-Dflat` option which makes the installation
  match what we want to ship for our download tarballs. This allows
  deleting a bunch of shell script logic from the CI.
  - for example it puts the executable directly in prefix/zig rather
    than prefix/bin/zig and it additionally includes prefix/LICENSE.
* build.zig: by default also install std lib documentation to doc/std/
  - this can be disabled by `-Dno-autodocs` similar to how there is
    already `-Dno-langref`.
* build.zig: add `std-docs` and `langref` steps which build and install
  the std lib autodocs and langref to prefix/doc/std and
  prefix/doc/langref.html, respectively.

* std.Build: implement proper handling of `-femit-docs` using the
  LazyPath system. This is a breaking change.
  - this is a partial implementation of #16351
* frontend: fixed the handling of Autodocs with regards to caching and
  putting the artifacts in the proper location to integrate with the
  build system.
  - closes #15864

* CI: delete the logic for autodocs since it is now handled by build.zig
  and is enabled by default.
  - in the future we should strive to have nearly all the CI shell
    script logic deleted in favor of `zig build` commands.
* CI: pass `-DZIG_NO_LIB=ON`/`-Dno-lib` except for the one command where
  we want to actually generate the langref and autodocs. Generating the
  langref takes 14 minutes right now (why?!) so we don't want to do that
  more times than necessary.

* Autodoc: fixed use of a global variable. It works fine as a local
  variable instead.
  - note that in the future we will want to make Autodoc run
    simultaneously using the job system, but for now the principle of
    YAGNI dictates that we don't have an init()/deinit() API and instead
    simply call the function that does the things.
* Autodoc: only do it when there are no compile errors

1 files changed, 17 insertions, 3 deletions

diff --git a/lib/std/Build/Step/Compile.zig b/lib/std/Build/Step/Compile.zig
index 22e88a0d71..7ff82e4b7b 100644
--- a/lib/std/Build/Step/Compile.zig
+++ b/lib/std/Build/Step/Compile.zig
@@ -49,7 +49,6 @@ verbose_cc: bool,
 emit_analysis: EmitOption = .default,
 emit_asm: EmitOption = .default,
 emit_bin: EmitOption = .default,
-emit_docs: EmitOption = .default,
 emit_implib: EmitOption = .default,
 emit_llvm_bc: EmitOption = .default,
 emit_llvm_ir: EmitOption = .default,
@@ -217,6 +216,7 @@ output_lib_path_source: GeneratedFile,
 output_h_path_source: GeneratedFile,
 output_pdb_path_source: GeneratedFile,
 output_dirname_source: GeneratedFile,
+generated_docs: ?*GeneratedFile,
 
 pub const CSourceFiles = struct {
     files: []const []const u8,
@@ -433,7 +433,7 @@ pub fn create(owner: *std.Build, options: Options) *Compile {
     }) catch @panic("OOM");
 
     const self = owner.allocator.create(Compile) catch @panic("OOM");
-    self.* = Compile{
+    self.* = .{
         .strip = null,
         .unwind_tables = null,
         .verbose_link = false,
@@ -486,6 +486,7 @@ pub fn create(owner: *std.Build, options: Options) *Compile {
         .output_h_path_source = GeneratedFile{ .step = &self.step },
         .output_pdb_path_source = GeneratedFile{ .step = &self.step },
         .output_dirname_source = GeneratedFile{ .step = &self.step },
+        .generated_docs = null,
 
         .target_info = target_info,
 
@@ -1004,6 +1005,15 @@ pub fn getOutputPdbSource(self: *Compile) FileSource {
     return .{ .generated = &self.output_pdb_path_source };
 }
 
+pub fn getOutputDocs(self: *Compile) FileSource {
+    assert(self.generated_docs == null); // This function may only be called once.
+    const arena = self.step.owner.allocator;
+    const generated_file = arena.create(GeneratedFile) catch @panic("OOM");
+    generated_file.* = .{ .step = &self.step };
+    self.generated_docs = generated_file;
+    return .{ .generated = generated_file };
+}
+
 pub fn addAssemblyFile(self: *Compile, path: []const u8) void {
     const b = self.step.owner;
     self.link_objects.append(.{
@@ -1509,7 +1519,7 @@ fn make(step: *Step, prog_node: *std.Progress.Node) !void {
     if (self.emit_analysis.getArg(b, "emit-analysis")) |arg| try zig_args.append(arg);
     if (self.emit_asm.getArg(b, "emit-asm")) |arg| try zig_args.append(arg);
     if (self.emit_bin.getArg(b, "emit-bin")) |arg| try zig_args.append(arg);
-    if (self.emit_docs.getArg(b, "emit-docs")) |arg| try zig_args.append(arg);
+    if (self.generated_docs != null) try zig_args.append("-femit-docs");
     if (self.emit_implib.getArg(b, "emit-implib")) |arg| try zig_args.append(arg);
     if (self.emit_llvm_bc.getArg(b, "emit-llvm-bc")) |arg| try zig_args.append(arg);
     if (self.emit_llvm_ir.getArg(b, "emit-llvm-ir")) |arg| try zig_args.append(arg);
@@ -2022,6 +2032,10 @@ fn make(step: *Step, prog_node: *std.Progress.Node) !void {
                 &.{ output_dir, self.out_pdb_filename },
             );
         }
+
+        if (self.generated_docs) |generated_docs| {
+            generated_docs.path = b.pathJoin(&.{ output_dir, "docs" });
+        }
     }
 
     if (self.kind == .lib and self.linkage != null and self.linkage.? == .dynamic and