std.build.TranslateCStep: add C macro support

The string construction code is moved out of std.build.LibExeObjStep
into std.build.constructCMacroArg, to allow reusing it elsewhere.

2 files changed, 36 insertions, 9 deletions

diff --git a/lib/std/build.zig b/lib/std/build.zig
index 395ccc5cb4..104aceea76 100644
--- a/lib/std/build.zig
+++ b/lib/std/build.zig
@@ -1862,15 +1862,7 @@ pub const LibExeObjStep = struct {
     /// If the value is omitted, it is set to 1.
     /// `name` and `value` need not live longer than the function call.
     pub fn defineCMacro(self: *LibExeObjStep, name: []const u8, value: ?[]const u8) void {
-        var macro = self.builder.allocator.alloc(
-            u8,
-            name.len + if (value) |value_slice| value_slice.len + 1 else 0,
-        ) catch |err| if (err == error.OutOfMemory) @panic("Out of memory") else unreachable;
-        mem.copy(u8, macro, name);
-        if (value) |value_slice| {
-            macro[name.len] = '=';
-            mem.copy(u8, macro[name.len + 1 ..], value_slice);
-        }
+        const macro = constructCMacro(self.builder.allocator, name, value);
         self.c_macros.append(macro) catch unreachable;
     }
 
@@ -2934,6 +2926,22 @@ pub const LibExeObjStep = struct {
     }
 };
 
+/// Allocates a new string for assigning a value to a named macro.
+/// If the value is omitted, it is set to 1.
+/// `name` and `value` need not live longer than the function call.
+pub fn constructCMacro(allocator: Allocator, name: []const u8, value: ?[]const u8) []const u8 {
+    var macro = allocator.alloc(
+        u8,
+        name.len + if (value) |value_slice| value_slice.len + 1 else 0,
+    ) catch |err| if (err == error.OutOfMemory) @panic("Out of memory") else unreachable;
+    mem.copy(u8, macro, name);
+    if (value) |value_slice| {
+        macro[name.len] = '=';
+        mem.copy(u8, macro[name.len + 1 ..], value_slice);
+    }
+    return macro;
+}
+
 pub const InstallArtifactStep = struct {
     pub const base_id = .install_artifact;
 
diff --git a/lib/std/build/TranslateCStep.zig b/lib/std/build/TranslateCStep.zig
index 0d44ebd80a..1f9bee463c 100644
--- a/lib/std/build/TranslateCStep.zig
+++ b/lib/std/build/TranslateCStep.zig
@@ -16,6 +16,7 @@ step: Step,
 builder: *Builder,
 source: build.FileSource,
 include_dirs: std.ArrayList([]const u8),
+c_macros: std.ArrayList([]const u8),
 output_dir: ?[]const u8,
 out_basename: []const u8,
 target: CrossTarget = CrossTarget{},
@@ -28,6 +29,7 @@ pub fn create(builder: *Builder, source: build.FileSource) *TranslateCStep {
         .builder = builder,
         .source = source,
         .include_dirs = std.ArrayList([]const u8).init(builder.allocator),
+        .c_macros = std.ArrayList([]const u8).init(builder.allocator),
         .output_dir = null,
         .out_basename = undefined,
         .output_file = build.GeneratedFile{ .step = &self.step },
@@ -53,6 +55,18 @@ pub fn addCheckFile(self: *TranslateCStep, expected_matches: []const []const u8)
     return CheckFileStep.create(self.builder, .{ .generated = &self.output_file }, self.builder.dupeStrings(expected_matches));
 }
 
+/// If the value is omitted, it is set to 1.
+/// `name` and `value` need not live longer than the function call.
+pub fn defineCMacro(self: *TranslateCStep, name: []const u8, value: ?[]const u8) void {
+    const macro = build.constructCMacro(self.builder.allocator, name, value);
+    self.c_macros.append(macro) catch unreachable;
+}
+
+/// name_and_value looks like [name]=[value]. If the value is omitted, it is set to 1.
+pub fn defineCMacroRaw(self: *TranslateCStep, name_and_value: []const u8) void {
+    self.c_macros.append(self.builder.dupe(name_and_value)) catch unreachable;
+}
+
 fn make(step: *Step) !void {
     const self = @fieldParentPtr(TranslateCStep, "step", step);
 
@@ -73,6 +87,11 @@ fn make(step: *Step) !void {
         try argv_list.append(include_dir);
     }
 
+    for (self.c_macros.items) |c_macro| {
+        try argv_list.append("-D");
+        try argv_list.append(c_macro);
+    }
+
     try argv_list.append(self.source.getPath(self.builder));
 
     const output_path_nl = try self.builder.execFromStep(argv_list.items, &self.step);