From f8b38a174f0c4a843688fe8adac09dc4f66cd585 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Mon, 13 Nov 2023 14:30:21 -0700
Subject: [PATCH] adjust building from source without LLVM process

The idea here is that the zig2 executable is perhaps the more useful
deliverable until we implement our own optimization passes. This will
allow system packages to provide Zig, and use it to compile Zig
projects, all without LLVM!
---
 README.md                  | 16 +++++++++-------
 bootstrap.c                | 11 -----------
 ci/x86_64-linux-debug.sh   |  3 ++-
 ci/x86_64-linux-release.sh |  3 ++-
 4 files changed, 13 insertions(+), 20 deletions(-)

diff --git a/README.md b/README.md
index 8eaeab7b95..13214b5bed 100644
--- a/README.md
+++ b/README.md
@@ -70,14 +70,13 @@ In this case, the only system dependency is a C compiler.
 
 ```
 cc -o bootstrap bootstrap.c
-./bootstrap build
+./bootstrap
 ```
 
-You can pass any options to this that you would pass to `zig build` (see
-`--help` for options).
-
-[Without LLVM extensions](https://github.com/ziglang/zig/issues/16270), a Zig
-compiler is missing these features:
+This produces a `zig2` executable in the current working directory. This is a
+"stage2" build of the compiler,
+[without LLVM extensions](https://github.com/ziglang/zig/issues/16270), and is
+therefore lacking these features:
 - Release mode optimizations
 - aarch64 machine code backend
 - `@cImport` / `zig translate-c`
@@ -86,7 +85,6 @@ compiler is missing these features:
 - [Some ELF linking features](https://github.com/ziglang/zig/issues/17749)
 - [Most COFF/PE linking features](https://github.com/ziglang/zig/issues/17751)
 - [Some WebAssembly linking features](https://github.com/ziglang/zig/issues/17750)
-- [COFF linking](https://github.com/ziglang/zig/issues/17751)
 - [Ability to output LLVM bitcode](https://github.com/ziglang/zig/issues/13265)
 - [Windows resource file compilation](https://github.com/ziglang/zig/issues/17752)
 - [Ability to create import libs from def files](https://github.com/ziglang/zig/issues/17807)
@@ -94,6 +92,10 @@ compiler is missing these features:
 - [Ability to create static archives from object files](https://github.com/ziglang/zig/issues/9828)
 - Ability to compile C++, Objective-C, and Objective-C++ files
 
+However, a compiler built this way does provide a C backend, which may be
+useful for creating system packages of Zig projects using the system C
+toolchain. In such case, LLVM is not needed!
+
 ## Contributing
 
 [Donate monthly](https://ziglang.org/zsf/).
diff --git a/bootstrap.c b/bootstrap.c
index 35ad33d266..f083c1cc1c 100644
--- a/bootstrap.c
+++ b/bootstrap.c
@@ -42,11 +42,6 @@ static void run(char **argv) {
     if (WEXITSTATUS(status) != 0)
         panic("child process failed");
 }
-
-static void run_execv(char **argv) {
-    if (execv(argv[0], argv) == -1 && errno == ENOENT) return;
-    perror("execv failed");
-}
 #endif
 
 static void print_and_run(const char **argv) {
@@ -87,9 +82,6 @@ static const char *get_host_triple(void) {
 }
 
 int main(int argc, char **argv) {
-    argv[0] = "./zig2";
-    run_execv(argv);
-
     const char *cc = get_c_compiler();
     const char *host_triple = get_host_triple();
 
@@ -188,7 +180,4 @@ int main(int argc, char **argv) {
         };
         print_and_run(child_argv);
     }
-
-    run_execv(argv);
-    panic("build script failed to create valid zig2 executable");
 }
diff --git a/ci/x86_64-linux-debug.sh b/ci/x86_64-linux-debug.sh
index bbab0c564d..6f3ebf642d 100755
--- a/ci/x86_64-linux-debug.sh
+++ b/ci/x86_64-linux-debug.sh
@@ -24,7 +24,8 @@ git fetch --tags
 git clean -fd
 rm -rf zig-out
 cc -o bootstrap bootstrap.c
-./bootstrap build -Dno-lib
+./bootstrap
+./zig2 build -Dno-lib
 # In order to run these behavior tests we need to move the `@cImport` ones to somewhere else.
 # ./zig-out/bin/zig test test/behavior.zig
 
diff --git a/ci/x86_64-linux-release.sh b/ci/x86_64-linux-release.sh
index 61320ce0f9..22222c7740 100755
--- a/ci/x86_64-linux-release.sh
+++ b/ci/x86_64-linux-release.sh
@@ -24,7 +24,8 @@ git fetch --tags
 git clean -fd
 rm -rf zig-out
 cc -o bootstrap bootstrap.c
-./bootstrap build -Dno-lib
+./bootstrap
+./zig2 build -Dno-lib
 # In order to run these behavior tests we need to move the `@cImport` ones to somewhere else.
 # ./zig-out/bin/zig test test/behavior.zig