A member's product directory holds every graph-built shared library of its closure

Author: speak-agent

.agents/docs/2026-09-29-workspace-build-graph-design.md

@@ -557,6 +557,7 @@ read from the member, or made a value of the plan:
 | a member's `[resources]`, `windows_code_page` | the virtual root's (empty) | per member: its directory and include directories, `res/<member>/`, its images only | e2e 837 |
 | `[build] linkage` | not copied to the virtual root | a root-position value | unit `RootPositionValuesSeparateMembers` |
 | unknown `mcpp:` capability, cfg() and schema warnings | not reported for a member | refused and reported for each selected member | e2e 836 M2, M3 |
+| the shared libraries of a member's closure | only those the member's units link were placed | every graph-built shared library of the closure, with its aliases, as §15 states | e2e 835 L3 |
 
 Each criterion fails on 2026.9.29.1 and passes on 2026.9.29.2. The resource
 case also showed a defect of every build: a quoted `#include` in a script was
@@ -565,5 +566,10 @@ include directories, so a script that relied on them could not be built. The
 scan now resolves as the compiler does (unit
 `InputsAreResolvedThroughTheIncludeDirectories`).
 
+The last row is not a read of the root's manifest: a root's program sits in
+`bin/` beside every graph-built library, so no build before the workspace plan
+needed the transitive set named. The index member `wayland` (libffi under
+libwayland-client) showed it.
+
 The rule the inventory missed is general: a virtual root answers for the plan,
 and a read of the root's manifest is correct only for a value of the plan.

CHANGELOG.md

@@ -9,8 +9,9 @@
 This release corrects what a workspace plan reads from its members. The plan's
 root is a virtual root that holds the values shared by the whole graph; five
 statements that a member makes about itself were read from that root in
-2026.9.29.1 and were therefore empty. The mcpp-index sweep of 2026.9.29.1 found
-the first two.
+2026.9.29.1 and were therefore empty, and a member's product directory lacked
+the shared libraries that its libraries need. The mcpp-index sweep of
+2026.9.29.1 found the first two.
 
 ### Fixed
 
@@ -28,6 +29,10 @@ the first two.
   member's programs and shared libraries only (e2e 837). A quoted `#include`
   or resource file in a script is now found through the include directories as
   the resource compiler finds it, in every build.
+- **A member's product directory holds every graph-built shared library of its
+  closure.** Only the libraries a member's own units link were placed, so a
+  library that another library needs (libffi under libwayland-client) was
+  missing and the program did not start (e2e 835 L3).
 - **`[build] linkage` is a value of the plan.** It chooses the C runtime that
   every object is compiled against, so members that differ in it are separate
   configurations, and the plan takes it from its members.

src/build/plan.cppm

@@ -3018,6 +3018,30 @@ make_plan(const mcpp::manifest::Manifest&         manifest,
             }
             units.push_back(std::move(lu));
         }
+        // Every graph-built shared library of the closure is placed beside
+        // the member's images, not only those its units link: a library that
+        // another shared library needs (libffi under libwayland-client) is
+        // found there, as it is in `bin/` beside a root's program.
+        const bool loadsLibraries = std::ranges::any_of(units, [](const LinkUnit& u) {
+            return u.kind != LinkUnit::StaticLibrary;
+        });
+        for (auto i : closureIdx) {
+            if (!loadsLibraries) break;
+            auto it = sharedTargetsByPackage.find(i);
+            if (it == sharedTargetsByPackage.end()) continue;
+            for (auto t : it->second) {
+                auto const& dep = sharedDepTargets[t];
+                std::vector<std::filesystem::path> files{dep.output};
+                for (auto const& alias : runtime_aliases_for_target(dep.target, naming))
+                    files.push_back(alias);
+                for (auto const& f : files) {
+                    if (f.parent_path() == productDir) continue;
+                    const bool seen = std::ranges::any_of(group.placements,
+                        [&](auto const& pl) { return pl.source == f; });
+                    if (!seen) group.placements.push_back({f, place(f)});
+                }
+            }
+        }
         // A program the closure ships through `artifacts` (mcpp#711) is linked
         // once, at `bin/`, and placed beside the member's programs, where a
         // program that launches it looks for it.

tests/e2e/835_a_shared_library_is_placed_by_a_link.sh

@@ -10,7 +10,10 @@
 #
 #   L1  each program runs from its product directory;
 #   L2  the library in the two product directories is one file (one inode),
-#       or, where links are not possible, two copies with equal content.
+#       or, where links are not possible, two copies with equal content;
+#   L3  a shared library that another shared library of the closure needs is
+#       placed too (2026.9.29.1 placed only the libraries a member's own units
+#       link, so a program whose library needs libffi did not start).
 set -e
 
 TMP=$(mktemp -d)
@@ -21,18 +24,30 @@ MCPP="${MCPP:-mcpp}"
 
 cat > mcpp.toml <<'EOF'
 [workspace]
-members = ["shlib", "p1", "p2"]
+members = ["base", "shlib", "p1", "p2"]
 EOF
-mkdir -p shlib/src p1/src p2/src
+mkdir -p base/src shlib/src p1/src p2/src
+cat > base/mcpp.toml <<'EOF'
+[package]
+name = "base"
+version = "0.1.0"
+
+[targets.base]
+kind = "shared"
+EOF
+printf 'export module basis;\nexport int base_v() { return 6; }\n' > base/src/base.cppm
 cat > shlib/mcpp.toml <<'EOF'
 [package]
 name = "shlib"
 version = "0.1.0"
 
+[dependencies]
+base = { path = "../base" }
+
 [targets.shlib]
 kind = "shared"
 EOF
-printf 'export module shlib;\nexport int shared_v() { return 7; }\n' > shlib/src/shlib.cppm
+printf 'export module shlib;\nimport basis;\nexport int shared_v() { return base_v() + 1; }\n' > shlib/src/shlib.cppm
 for p in p1 p2; do
     cat > $p/mcpp.toml <<EOF
 [package]
@@ -71,4 +86,10 @@ if [ "$ia" != "$ib" ]; then
     echo "note: the placements are copies on this file system"
 fi
 
+# L3
+for p in p1 p2; do
+    [ -n "$(find "$dir/$p" -maxdepth 1 -name 'libbase.so*' | head -1)" ] \
+        || fail "L3: libbase, which libshlib needs, is not placed in bin/$p/" b.log
+done
+
 echo "PASS: 835_a_shared_library_is_placed_by_a_link"