also find base project package

base/loading.jl

@@ -693,6 +693,14 @@ function manifest_uuid_path(env::String, pkg::PkgId)::Union{Nothing,String,Missi
  # if `pkg` matches the project, return the project itself
  return project_file_path(project_file)
  end
+ base_project_file = base_project(project_file)
+ if base_proejct_file !== nothing
+ base_proj = project_file_name_uuid(base_project_file, pkg.name)
+ if base_proj == pkg
+ # if `pkg` matches the project, return the project itself
+ return project_file_path(base_project_file)
+ end
+ end
  mby_ext = project_file_ext_path(project_file, pkg.name)
  mby_ext === nothing || return mby_ext
  # look for manifest file and `where` stanza

test/loading.jl

@@ -1561,6 +1561,8 @@ end
  @test isfile(Base.locate_package(id))
  id2 = Base.identify_package("Devved2")
  @test isfile(Base.locate_package(id2))
+ id3 = Base.identify_package("MyPkg")
+ @test isfile(Base.locate_package(id3))
  finally
  copy!(LOAD_PATH, old_load_path)
  end

test/project/SubProject/Manifest.toml

@@ -0,0 +1,15 @@
+# This file is machine-generated - editing it directly is not advised
+
+julia_version = "1.12.0-DEV"
+manifest_format = "2.0"
+project_hash = "620b9377bc807ff657e6618c8ccc24887eb40285"
+
+[[deps.Devved]]
+path = "Devved"
+uuid = "cbce3a6e-7a3d-4e84-8e6d-b87208df7599"
+version = "0.1.0"
+
+[[deps.Devved2]]
+path = "Devved2"
+uuid = "08f74b90-50f5-462f-80b9-a72b1258a17b"
+version = "0.1.0"

test/project/SubProject/Project.toml

@@ -1,3 +1,6 @@
+name = "MyPkg"
+uuid = "0cafdeb2-d7a2-40d0-8d22-4411fcc2c4ee"
+
 subprojects = ["sub"]
 
 [deps]

test/project/SubProject/src/MyPkg.jl

@@ -0,0 +1,3 @@
+module MyPkg
+
+end