Account for dependency boundaries when duping headers

This is a temporary workaround that can be revered if/when 'path'
lazy paths are updated to encode which build root they are relative to.

1 files changed, 27 insertions, 4 deletions

diff --git a/lib/std/Build/Step/Compile.zig b/lib/std/Build/Step/Compile.zig
index 2883992c73..4a5364176a 100644
--- a/lib/std/Build/Step/Compile.zig
+++ b/lib/std/Build/Step/Compile.zig
@@ -264,8 +264,20 @@ pub const HeaderInstallation = union(enum) {
         dest_rel_path: []const u8,
 
         pub fn dupe(self: File, b: *std.Build) File {
+            // 'path' lazy paths are relative to the build root of some step, inferred from the step
+            // in which they are used. This means that we can't dupe such paths, because they may
+            // come from dependencies with their own build roots and duping the paths as is might
+            // cause the build script to search for the file relative to the wrong root.
+            // As a temporary workaround, we convert build root-relative paths to absolute paths.
+            // If/when the build-root relative paths are updated to encode which build root they are
+            // relative to, this workaround should be removed.
+            const duped_source: LazyPath = switch (self.source) {
+                .path => |root_rel| .{ .cwd_relative = b.pathFromRoot(root_rel) },
+                else => self.source.dupe(b),
+            };
+
             return .{
-                .source = self.source.dupe(b),
+                .source = duped_source,
                 .dest_rel_path = b.dupePath(self.dest_rel_path),
             };
         }
@@ -293,8 +305,20 @@ pub const HeaderInstallation = union(enum) {
         };
 
         pub fn dupe(self: Directory, b: *std.Build) Directory {
+            // 'path' lazy paths are relative to the build root of some step, inferred from the step
+            // in which they are used. This means that we can't dupe such paths, because they may
+            // come from dependencies with their own build roots and duping the paths as is might
+            // cause the build script to search for the file relative to the wrong root.
+            // As a temporary workaround, we convert build root-relative paths to absolute paths.
+            // If/when the build-root relative paths are updated to encode which build root they are
+            // relative to, this workaround should be removed.
+            const duped_source: LazyPath = switch (self.source) {
+                .path => |root_rel| .{ .cwd_relative = b.pathFromRoot(root_rel) },
+                else => self.source.dupe(b),
+            };
+
             return .{
-                .source = self.source.dupe(b),
+                .source = duped_source,
                 .dest_rel_path = b.dupePath(self.dest_rel_path),
                 .options = self.options.dupe(b),
             };
@@ -492,9 +516,8 @@ pub fn installConfigHeader(cs: *Compile, config_header: *Step.ConfigHeader) void
 /// module's include search path.
 pub fn installLibraryHeaders(cs: *Compile, lib: *Compile) void {
     assert(lib.kind == .lib);
-    const b = cs.step.owner;
     for (lib.installed_headers.items) |installation| {
-        const installation_copy = installation.dupe(b);
+        const installation_copy = installation.dupe(lib.step.owner);
         cs.installed_headers.append(installation_copy) catch @panic("OOM");
         cs.addHeaderInstallationToIncludeTree(installation_copy);
         installation_copy.getSource().addStepDependencies(&cs.step);