From 8627858bbc2fee848e2f3e3ca64dc944f39591e5 Mon Sep 17 00:00:00 2001
From: Luuk de Gram <luuk@degram.dev>
Date: Fri, 26 Aug 2022 17:29:43 +0200
Subject: [PATCH] test/link: add test for extern resolution

Adds a linker tests to verify extern/undefined symbols
representing non-functions are being resolved correctly.
---
 src/arch/wasm/CodeGen.zig       |  2 +-
 test/link.zig                   |  6 ++++++
 test/link/wasm/extern/build.zig | 17 +++++++++++++++++
 test/link/wasm/extern/foo.c     |  1 +
 test/link/wasm/extern/main.zig  |  8 ++++++++
 5 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 test/link/wasm/extern/build.zig
 create mode 100644 test/link/wasm/extern/foo.c
 create mode 100644 test/link/wasm/extern/main.zig

diff --git a/src/arch/wasm/CodeGen.zig b/src/arch/wasm/CodeGen.zig
index e09822c208..b9637bf8e3 100644
--- a/src/arch/wasm/CodeGen.zig
+++ b/src/arch/wasm/CodeGen.zig
@@ -2355,7 +2355,7 @@ fn lowerDeclRefValue(self: *Self, tv: TypedValue, decl_index: Module.Decl.Index)
 
     const module = self.bin_file.base.options.module.?;
     const decl = module.declPtr(decl_index);
-    if (!decl.ty.hasRuntimeBitsIgnoreComptime()) {
+    if (decl.ty.zigTypeTag() != .Fn and !decl.ty.hasRuntimeBitsIgnoreComptime()) {
         return WValue{ .imm32 = 0xaaaaaaaa };
     }
 
diff --git a/test/link.zig b/test/link.zig
index 215a0511fc..b68353122c 100644
--- a/test/link.zig
+++ b/test/link.zig
@@ -52,6 +52,12 @@ fn addWasmCases(cases: *tests.StandaloneContext) void {
         .build_modes = true,
         .requires_stage2 = true,
     });
+
+    cases.addBuildFile("test/link/wasm/extern/build.zig", .{
+        .build_modes = true,
+        .requires_stage2 = true,
+        .use_emulation = true,
+    });
 }
 
 fn addMachOCases(cases: *tests.StandaloneContext) void {
diff --git a/test/link/wasm/extern/build.zig b/test/link/wasm/extern/build.zig
new file mode 100644
index 0000000000..88cce88d98
--- /dev/null
+++ b/test/link/wasm/extern/build.zig
@@ -0,0 +1,17 @@
+const std = @import("std");
+
+pub fn build(b: *std.build.Builder) void {
+    const mode = b.standardReleaseOptions();
+    const exe = b.addExecutable("extern", "main.zig");
+    exe.setTarget(.{ .cpu_arch = .wasm32, .os_tag = .wasi });
+    exe.setBuildMode(mode);
+    exe.addCSourceFile("foo.c", &.{});
+    exe.use_llvm = false;
+    exe.use_lld = false;
+
+    const run = exe.runEmulatable();
+    run.expectStdOutEqual("Result: 30");
+
+    const test_step = b.step("test", "Run linker test");
+    test_step.dependOn(&run.step);
+}
diff --git a/test/link/wasm/extern/foo.c b/test/link/wasm/extern/foo.c
new file mode 100644
index 0000000000..0dafd7e112
--- /dev/null
+++ b/test/link/wasm/extern/foo.c
@@ -0,0 +1 @@
+int foo = 30;
diff --git a/test/link/wasm/extern/main.zig b/test/link/wasm/extern/main.zig
new file mode 100644
index 0000000000..b9fa1226eb
--- /dev/null
+++ b/test/link/wasm/extern/main.zig
@@ -0,0 +1,8 @@
+const std = @import("std");
+
+extern const foo: u32;
+
+pub fn main() void {
+    const std_out = std.io.getStdOut();
+    std_out.writer().print("Result: {d}", .{foo}) catch {};
+}