From 7377dce368090e3c49a15d8996cc812adadd3d43 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Tue, 30 Aug 2022 12:43:10 -0700
Subject: avoid exposing supportsTailCall in the standard library

This is problematic because in practice it depends on whether the
compiler backend supports it too, as evidenced by the TODO comment about
LLVM not supporting some architectures that in fact do support tail
calls.

Instead this logic is organized strategically in src/target.zig, part of
the internal compiler source code, and the behavior tests in question
duplicate some logic for deciding whether to proceed with the test.

The proper place to expose this flag is in `@import("builtin")` - the
generated source file - so that third party compilers can advertise
whether they support tail calls.
---
 src/Compilation.zig | 36 +++++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 17 deletions(-)

(limited to 'src/Compilation.zig')

diff --git a/src/Compilation.zig b/src/Compilation.zig
index 8e4b322230..c1321e40cf 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -4766,6 +4766,24 @@ pub fn dump_argv(argv: []const []const u8) void {
     std.debug.print("{s}\n", .{argv[argv.len - 1]});
 }
 
+pub fn getZigBackend(comp: Compilation) std.builtin.CompilerBackend {
+    const use_stage1 = build_options.have_stage1 and comp.bin_file.options.use_stage1;
+    if (use_stage1) return .stage1;
+    if (build_options.have_llvm and comp.bin_file.options.use_llvm) return .stage2_llvm;
+    const target = comp.bin_file.options.target;
+    if (target.ofmt == .c) return .stage2_c;
+    return switch (target.cpu.arch) {
+        .wasm32, .wasm64 => std.builtin.CompilerBackend.stage2_wasm,
+        .arm, .armeb, .thumb, .thumbeb => .stage2_arm,
+        .x86_64 => .stage2_x86_64,
+        .i386 => .stage2_x86,
+        .aarch64, .aarch64_be, .aarch64_32 => .stage2_aarch64,
+        .riscv64 => .stage2_riscv64,
+        .sparc64 => .stage2_sparc64,
+        else => .other,
+    };
+}
+
 pub fn generateBuiltinZigSource(comp: *Compilation, allocator: Allocator) Allocator.Error![:0]u8 {
     const tracy_trace = trace(@src());
     defer tracy_trace.end();
@@ -4775,23 +4793,7 @@ pub fn generateBuiltinZigSource(comp: *Compilation, allocator: Allocator) Alloca
 
     const target = comp.getTarget();
     const generic_arch_name = target.cpu.arch.genericName();
-    const use_stage1 = build_options.have_stage1 and comp.bin_file.options.use_stage1;
-
-    const zig_backend: std.builtin.CompilerBackend = blk: {
-        if (use_stage1) break :blk .stage1;
-        if (build_options.have_llvm and comp.bin_file.options.use_llvm) break :blk .stage2_llvm;
-        if (target.ofmt == .c) break :blk .stage2_c;
-        break :blk switch (target.cpu.arch) {
-            .wasm32, .wasm64 => std.builtin.CompilerBackend.stage2_wasm,
-            .arm, .armeb, .thumb, .thumbeb => .stage2_arm,
-            .x86_64 => .stage2_x86_64,
-            .i386 => .stage2_x86,
-            .aarch64, .aarch64_be, .aarch64_32 => .stage2_aarch64,
-            .riscv64 => .stage2_riscv64,
-            .sparc64 => .stage2_sparc64,
-            else => .other,
-        };
-    };
+    const zig_backend = comp.getZigBackend();
 
     @setEvalBranchQuota(4000);
     try buffer.writer().print(
-- 
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