1 files changed, 58 insertions, 19 deletions

diff --git a/src/Compilation.zig b/src/Compilation.zig
index 23f67f5b37..5b06bd6370 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -26,6 +26,8 @@ const Module = @import("Module.zig");
 const Cache = @import("Cache.zig");
 const stage1 = @import("stage1.zig");
 const translate_c = @import("translate_c.zig");
+const c_codegen = @import("codegen/c.zig");
+const c_link = @import("link/C.zig");
 const ThreadPool = @import("ThreadPool.zig");
 const WaitGroup = @import("WaitGroup.zig");
 
@@ -131,6 +133,7 @@ emit_asm: ?EmitLoc,
 emit_llvm_ir: ?EmitLoc,
 emit_analysis: ?EmitLoc,
 emit_docs: ?EmitLoc,
+c_header: ?c_link.Header,
 
 pub const InnerError = Module.InnerError;
 
@@ -895,10 +898,6 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             };
         };
 
-        if (!use_llvm and options.emit_h != null) {
-            fatal("TODO implement support for -femit-h in the self-hosted backend", .{});
-        }
-
         var system_libs: std.StringArrayHashMapUnmanaged(void) = .{};
         errdefer system_libs.deinit(gpa);
         try system_libs.ensureCapacity(gpa, options.system_libs.len);
@@ -975,6 +974,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             .global_cache_directory = options.global_cache_directory,
             .bin_file = bin_file,
             .emit_h = options.emit_h,
+            .c_header = if (!use_llvm and options.emit_h != null) c_link.Header.init(gpa) else null,
             .emit_asm = options.emit_asm,
             .emit_llvm_ir = options.emit_llvm_ir,
             .emit_analysis = options.emit_analysis,
@@ -1286,6 +1286,20 @@ pub fn update(self: *Compilation) !void {
             module.root_scope.unload(self.gpa);
         }
     }
+
+    // If we've chosen to emit a C header, flush the header to the disk.
+    if (self.c_header) |header| {
+        const header_path = self.emit_h.?;
+        // If a directory has been provided, write the header there. Otherwise, just write it to the
+        // cache directory.
+        const header_dir = if (header_path.directory) |dir|
+            dir.handle
+        else
+            self.local_cache_directory.handle;
+        const header_file = try header_dir.createFile(header_path.basename, .{});
+        defer header_file.close();
+        try header.flush(header_file.writer());
+    }
 }
 
 /// Having the file open for writing is problematic as far as executing the
@@ -1385,6 +1399,9 @@ pub fn performAllTheWork(self: *Compilation) error{ TimerUnsupported, OutOfMemor
     var c_comp_progress_node = main_progress_node.start("Compile C Objects", self.c_source_files.len);
     defer c_comp_progress_node.end();
 
+    var arena = std.heap.ArenaAllocator.init(self.gpa);
+    defer arena.deinit();
+
     var wg = WaitGroup{};
     defer wg.wait();
 
@@ -1432,22 +1449,44 @@ pub fn performAllTheWork(self: *Compilation) error{ TimerUnsupported, OutOfMemor
 
                 assert(decl.typed_value.most_recent.typed_value.ty.hasCodeGenBits());
 
-                self.bin_file.updateDecl(module, decl) catch |err| switch (err) {
-                    error.OutOfMemory => return error.OutOfMemory,
-                    error.AnalysisFail => {
-                        decl.analysis = .dependency_failure;
-                    },
-                    else => {
-                        try module.failed_decls.ensureCapacity(module.gpa, module.failed_decls.items().len + 1);
-                        module.failed_decls.putAssumeCapacityNoClobber(decl, try ErrorMsg.create(
-                            module.gpa,
-                            decl.src(),
-                            "unable to codegen: {}",
-                            .{@errorName(err)},
-                        ));
-                        decl.analysis = .codegen_failure_retryable;
-                    },
+                self.bin_file.updateDecl(module, decl) catch |err| {
+                    switch (err) {
+                        error.OutOfMemory => return error.OutOfMemory,
+                        error.AnalysisFail => {
+                            decl.analysis = .dependency_failure;
+                        },
+                        else => {
+                            try module.failed_decls.ensureCapacity(module.gpa, module.failed_decls.items().len + 1);
+                            module.failed_decls.putAssumeCapacityNoClobber(decl, try ErrorMsg.create(
+                                module.gpa,
+                                decl.src(),
+                                "unable to codegen: {}",
+                                .{@errorName(err)},
+                            ));
+                            decl.analysis = .codegen_failure_retryable;
+                        },
+                    }
+                    return;
                 };
+
+                if (self.c_header) |*header| {
+                    c_codegen.generateHeader(&arena, module, &header.*, decl) catch |err| switch (err) {
+                        error.OutOfMemory => return error.OutOfMemory,
+                        error.AnalysisFail => {
+                            decl.analysis = .dependency_failure;
+                        },
+                        else => {
+                            try module.failed_decls.ensureCapacity(module.gpa, module.failed_decls.items().len + 1);
+                            module.failed_decls.putAssumeCapacityNoClobber(decl, try ErrorMsg.create(
+                                module.gpa,
+                                decl.src(),
+                                "unable to generate C header: {}",
+                                .{@errorName(err)},
+                            ));
+                            decl.analysis = .codegen_failure_retryable;
+                        },
+                    };
+                }
             },
         },
         .analyze_decl => |decl| {