From fb50ae9e71003bf4a7445267fdc92036d1016637 Mon Sep 17 00:00:00 2001
From: Evan Haas <evan@lagerdata.com>
Date: Tue, 31 Aug 2021 10:30:36 -0700
Subject: [PATCH] translate-c: emit compileError for undefined identifiers in
 macros

---
 src/translate_c.zig  | 20 ++++++++++++++++++++
 test/translate_c.zig | 12 ++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/src/translate_c.zig b/src/translate_c.zig
index 6b7165176b68..0f13d4176fa3 100644
--- a/src/translate_c.zig
+++ b/src/translate_c.zig
@@ -5248,6 +5248,23 @@ const MacroCtx = struct {
     fn makeSlicer(self: *const MacroCtx) MacroSlicer {
         return MacroSlicer{ .source = self.source, .tokens = self.list };
     }
+
+    fn containsUndefinedIdentifier(self: *MacroCtx, scope: *Scope) ?[]const u8 {
+        const slicer = self.makeSlicer();
+        var i: usize = 1; // index 0 is the macro name
+        while (i < self.list.len) : (i += 1) {
+            const token = self.list[i];
+            switch (token.id) {
+                .Period => i += 1, // skip next token since field identifiers can be unknown
+                .Identifier => {
+                    const identifier = slicer.slice(token);
+                    if (!scope.contains(identifier)) return identifier;
+                },
+                else => {},
+            }
+        }
+        return null;
+    }
 };
 
 fn tokenizeMacro(source: []const u8, tok_list: *std.ArrayList(CToken)) Error!void {
@@ -5344,6 +5361,9 @@ fn transPreprocessorEntities(c: *Context, unit: *clang.ASTUnit) Error!void {
 fn transMacroDefine(c: *Context, m: *MacroCtx) ParseError!void {
     const scope = &c.global_scope.base;
 
+    if (m.containsUndefinedIdentifier(scope)) |ident|
+        return m.fail(c, "unable to translate macro: undefined identifier `{s}`", .{ident});
+
     const init_node = try parseCExpr(c, m, scope);
     const last = m.next().?;
     if (last != .Eof and last != .Nl)
diff --git a/test/translate_c.zig b/test/translate_c.zig
index 70ff464c8aa4..8286843d8730 100644
--- a/test/translate_c.zig
+++ b/test/translate_c.zig
@@ -228,6 +228,7 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
     });
 
     cases.add("macro expressions respect C operator precedence",
+        \\int *foo = 0;
         \\#define FOO *((foo) + 2)
         \\#define VALUE  (1 + 2 * 3 + 4 * 5 + 6 << 7 | 8 == 9)
         \\#define _AL_READ3BYTES(p)   ((*(unsigned char *)(p))            \
@@ -459,6 +460,7 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
     });
 
     cases.add("macro line continuation",
+        \\int BAR = 0;
         \\#define FOO -\
         \\BAR
     , &[_][]const u8{
@@ -1833,6 +1835,7 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
     });
 
     cases.add("macro pointer cast",
+        \\#define NRF_GPIO_BASE 0
         \\typedef struct { int dummy; } NRF_GPIO_Type;
         \\#define NRF_GPIO ((NRF_GPIO_Type *) NRF_GPIO_BASE)
     , &[_][]const u8{
@@ -1873,6 +1876,7 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
     });
 
     cases.add("macro add",
+        \\#define D3_AHB1PERIPH_BASE 0
         \\#define PERIPH_BASE               (0x40000000UL) /*!< Base address of : AHB/APB Peripherals                                                   */
         \\#define D3_APB1PERIPH_BASE       (PERIPH_BASE + 0x18000000UL)
         \\#define RCC_BASE              (D3_AHB1PERIPH_BASE + 0x4400UL)
@@ -3138,6 +3142,7 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
         \\#define FOO(bar) baz((void *)(baz))
         \\#define BAR (void*) a
         \\#define BAZ (uint32_t)(2)
+        \\#define a 2
     , &[_][]const u8{
         \\pub inline fn FOO(bar: anytype) @TypeOf(baz(@import("std").zig.c_translation.cast(?*c_void, baz))) {
         \\    _ = bar;
@@ -3160,6 +3165,7 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
     });
 
     cases.add("macro conditional operator",
+        \\ int a, b, c;
         \\#define FOO a ? b : c
     , &[_][]const u8{
         \\pub const FOO = if (a) b else c;
@@ -3649,4 +3655,10 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
         ,
         \\_ = p[@intCast(c_uint, @as(c_int, 1))];
     });
+
+    cases.add("Undefined macro identifier",
+        \\#define FOO BAR
+    , &[_][]const u8{
+        \\pub const FOO = @compileError("unable to translate macro: undefined identifier `BAR`");
+    });
 }