translate-c: add framework for special-casing macros

Some macros (for example any macro that uses token pasting) cannot be
directly translated to Zig, but may nevertheless still admit a Zig
implementation. This provides a mechanism for matching macros against
templates and mapping them to functions implemented in c_translation.zig.

A macro matches a template if it contains the same sequence of tokens, except
that the name and parameters may be renamed. No attempt is made to
semantically analyze the macro. For example the following two macros are
considered equivalent:

```C
```

But the following two are not:

```C
```

1 files changed, 80 insertions, 0 deletions

diff --git a/lib/std/zig/c_translation.zig b/lib/std/zig/c_translation.zig
index 7851525bb7..071ce01396 100644
--- a/lib/std/zig/c_translation.zig
+++ b/lib/std/zig/c_translation.zig
@@ -350,3 +350,83 @@ test "Flexible Array Type" {
     try testing.expectEqual(FlexibleArrayType(*volatile Container, c_int), [*c]volatile c_int);
     try testing.expectEqual(FlexibleArrayType(*const volatile Container, c_int), [*c]const volatile c_int);
 }
+
+pub const Macros = struct {
+    pub fn U_SUFFIX(comptime n: comptime_int) @TypeOf(promoteIntLiteral(c_uint, n, .decimal)) {
+        return promoteIntLiteral(c_uint, n, .decimal);
+    }
+
+    fn L_SUFFIX_ReturnType(comptime number: anytype) type {
+        switch (@TypeOf(number)) {
+            comptime_int => return @TypeOf(promoteIntLiteral(c_long, number, .decimal)),
+            comptime_float => return c_longdouble,
+            else => @compileError("Invalid value for L suffix"),
+        }
+    }
+    pub fn L_SUFFIX(comptime number: anytype) L_SUFFIX_ReturnType(number) {
+        switch (@TypeOf(number)) {
+            comptime_int => return promoteIntLiteral(c_long, number, .decimal),
+            comptime_float => @compileError("TODO: c_longdouble initialization from comptime_float not supported"),
+            else => @compileError("Invalid value for L suffix"),
+        }
+    }
+
+    pub fn UL_SUFFIX(comptime n: comptime_int) @TypeOf(promoteIntLiteral(c_ulong, n, .decimal)) {
+        return promoteIntLiteral(c_ulong, n, .decimal);
+    }
+
+    pub fn LL_SUFFIX(comptime n: comptime_int) @TypeOf(promoteIntLiteral(c_longlong, n, .decimal)) {
+        return promoteIntLiteral(c_longlong, n, .decimal);
+    }
+
+    pub fn ULL_SUFFIX(comptime n: comptime_int) @TypeOf(promoteIntLiteral(c_ulonglong, n, .decimal)) {
+        return promoteIntLiteral(c_ulonglong, n, .decimal);
+    }
+
+    pub fn F_SUFFIX(comptime f: comptime_float) f32 {
+        return @as(f32, f);
+    }
+
+    pub fn WL_CONTAINER_OF(ptr: anytype, sample: anytype, comptime member: []const u8) @TypeOf(sample) {
+        return @fieldParentPtr(@TypeOf(sample.*), member, ptr);
+    }
+};
+
+test "Macro suffix functions" {
+    try testing.expect(@TypeOf(Macros.F_SUFFIX(1)) == f32);
+
+    try testing.expect(@TypeOf(Macros.U_SUFFIX(1)) == c_uint);
+    if (math.maxInt(c_ulong) > math.maxInt(c_uint)) {
+        try testing.expect(@TypeOf(Macros.U_SUFFIX(math.maxInt(c_uint) + 1)) == c_ulong);
+    }
+    if (math.maxInt(c_ulonglong) > math.maxInt(c_ulong)) {
+        try testing.expect(@TypeOf(Macros.U_SUFFIX(math.maxInt(c_ulong) + 1)) == c_ulonglong);
+    }
+
+    try testing.expect(@TypeOf(Macros.L_SUFFIX(1)) == c_long);
+    if (math.maxInt(c_long) > math.maxInt(c_int)) {
+        try testing.expect(@TypeOf(Macros.L_SUFFIX(math.maxInt(c_int) + 1)) == c_long);
+    }
+    if (math.maxInt(c_longlong) > math.maxInt(c_long)) {
+        try testing.expect(@TypeOf(Macros.L_SUFFIX(math.maxInt(c_long) + 1)) == c_longlong);
+    }
+
+    try testing.expect(@TypeOf(Macros.UL_SUFFIX(1)) == c_ulong);
+    if (math.maxInt(c_ulonglong) > math.maxInt(c_ulong)) {
+        try testing.expect(@TypeOf(Macros.UL_SUFFIX(math.maxInt(c_ulong) + 1)) == c_ulonglong);
+    }
+
+    try testing.expect(@TypeOf(Macros.LL_SUFFIX(1)) == c_longlong);
+    try testing.expect(@TypeOf(Macros.ULL_SUFFIX(1)) == c_ulonglong);
+}
+
+test "WL_CONTAINER_OF" {
+    const S = struct {
+        a: u32 = 0,
+        b: u32 = 0,
+    };
+    var x = S{};
+    var y = S{};
+    var ptr = Macros.WL_CONTAINER_OF(&x.b, &y, "b");
+    try testing.expectEqual(&x, ptr);
+}