AstGen: lower function addrspace expression correctly

Also, add some basic behavior tests for addrspace and linksection which
would have caught this bug in CI.

test/behavior/addrspace_and_linksection.zig

@@ -0,0 +1,120 @@
+const builtin = @import("builtin");
+
+/// Elements are const_linksection, var_linksection, fn_linksection
+const linksections: ?[3][]const u8 = switch (builtin.target.ofmt) {
+    .elf => .{ ".rodata", ".data", ".text" },
+    .coff => .{ ".rdata", ".data", ".text" },
+    .macho => .{ "__TEXT,__const", "__DATA,__data", "__TEXT,__text" },
+    else => null,
+};
+const const_linksection = linksections.?[0];
+const var_linksection = linksections.?[1];
+const fn_linksection = linksections.?[2];
+
+test "addrspace on container-level const" {
+    const S = struct {
+        const a: u32 addrspace(.generic) = 123;
+        fn check(ptr: anytype) !void {
+            if (ptr.* != 123) return error.TestFailed;
+        }
+    };
+    try S.check(&S.a);
+    try comptime S.check(&S.a);
+}
+
+test "linksection on container-level const" {
+    if (linksections == null) return;
+    const S = struct {
+        const a: u32 linksection(const_linksection) = 123;
+        fn check(ptr: anytype) !void {
+            if (ptr.* != 123) return error.TestFailed;
+        }
+    };
+    try S.check(&S.a);
+    try comptime S.check(&S.a);
+}
+
+test "addrspace and linksection on container-level const" {
+    if (linksections == null) return;
+    const S = struct {
+        const a: u32 addrspace(.generic) linksection(const_linksection) = 123;
+        fn check(ptr: anytype) !void {
+            if (ptr.* != 123) return error.TestFailed;
+        }
+    };
+    try S.check(&S.a);
+    try comptime S.check(&S.a);
+}
+
+test "addrspace on container-level var" {
+    const S = struct {
+        var a: u32 addrspace(.generic) = 123;
+        fn check(ptr: anytype) !void {
+            if (ptr.* != 123) return error.TestFailed;
+        }
+    };
+    try S.check(&S.a);
+}
+
+test "linksection on container-level var" {
+    if (linksections == null) return;
+    const S = struct {
+        var a: u32 linksection(var_linksection) = 123;
+        fn check(ptr: anytype) !void {
+            if (ptr.* != 123) return error.TestFailed;
+        }
+    };
+    try S.check(&S.a);
+}
+
+test "addrspace and linksection on container-level var" {
+    if (linksections == null) return;
+    const S = struct {
+        var a: u32 addrspace(.generic) linksection(var_linksection) = 123;
+        fn check(ptr: anytype) !void {
+            if (ptr.* != 123) return error.TestFailed;
+        }
+    };
+    try S.check(&S.a);
+}
+
+test "addrspace on fn" {
+    const S = struct {
+        fn f() addrspace(.generic) u32 {
+            return 123;
+        }
+        fn check(fnPtr: anytype) !void {
+            if (fnPtr() != 123) return error.TestFailed;
+        }
+    };
+    try S.check(&S.f);
+    try comptime S.check(&S.f);
+}
+
+test "linksection on fn" {
+    if (linksections == null) return;
+    const S = struct {
+        fn f() linksection(fn_linksection) u32 {
+            return 123;
+        }
+        fn check(fnPtr: anytype) !void {
+            if (fnPtr() != 123) return error.TestFailed;
+        }
+    };
+    try S.check(&S.f);
+    try comptime S.check(&S.f);
+}
+
+test "addrspace and linksection on fn" {
+    if (linksections == null) return;
+    const S = struct {
+        fn f() addrspace(.generic) linksection(fn_linksection) u32 {
+            return 123;
+        }
+        fn check(fnPtr: anytype) !void {
+            if (fnPtr() != 123) return error.TestFailed;
+        }
+    };
+    try S.check(&S.f);
+    try comptime S.check(&S.f);
+}

test/behavior/type_info_mul_linksection_addrspace_decls.zig

@@ -1,12 +0,0 @@
-const std = @import("std");
-const expect = std.testing.expect;
-
-pub const a linksection("sec_a") = 0;
-pub const b linksection("sec_b") = 0;
-pub const c addrspace("space_c") = 0;
-pub const d addrspace("space_d") = 0;
-
-test {
-    const decls = @typeInfo(@This()).@"struct".decls;
-    try expect(decls.len == 4);
-}