From 0cc033e333261bb4b4f7e9689c5fafdc5cc65c23 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2@gmail.com>
Date: Mon, 22 Aug 2022 12:00:40 -0400
Subject: [PATCH] [runtimes] Handle interface targets in runtimes distribution
 components

As reported in [1], cxx-headers is not a valid distribution target
because it is an interface target in CMake. This breaks the most
basic MultiDistributionExample of the runtimes build.

This patch handles interface targets by getting rid of the assumption
that all distribution components have a target associated to them. It
is valid for a distribution component to only have a `install-FOO`
target.

In the case where only `cxx-headers` is provided as a distribution
component, `ninja toolchain-distribution` will not build anything
after this patch, since there is effectively nothing to build for
the `cxx-headers` target. However, running `ninja install-toolchain-distribution`
will build everything, as expected.

[1]: https://discord.com/channels/636084430946959380/636732894974312448/1010013287464828968

Differential Revision: https://reviews.llvm.org/D132387

(cherry picked from commit 5905e699342fd476d7eb9e35db5d84248a7e9156)
---
 llvm/cmake/modules/LLVMDistributionSupport.cmake | 4 ++--
 llvm/runtimes/CMakeLists.txt                     | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/llvm/cmake/modules/LLVMDistributionSupport.cmake b/llvm/cmake/modules/LLVMDistributionSupport.cmake
index a2fe69df1e7e63..526f36dcda830c 100644
--- a/llvm/cmake/modules/LLVMDistributionSupport.cmake
+++ b/llvm/cmake/modules/LLVMDistributionSupport.cmake
@@ -260,10 +260,10 @@ function(llvm_distribution_add_targets)
     add_custom_target(install-${distribution_target}-stripped)
 
     foreach(target ${distribution_components})
+      # Note that some distribution components may not have an actual target, but only an install-FOO target.
+      # This happens for example if a target is an INTERFACE target.
       if(TARGET ${target})
         add_dependencies(${distribution_target} ${target})
-      else()
-        message(SEND_ERROR "Specified distribution component '${target}' doesn't have a target")
       endif()
 
       if(TARGET install-${target})
diff --git a/llvm/runtimes/CMakeLists.txt b/llvm/runtimes/CMakeLists.txt
index 34fcccab100c5f..1ba462c51ae87c 100644
--- a/llvm/runtimes/CMakeLists.txt
+++ b/llvm/runtimes/CMakeLists.txt
@@ -214,7 +214,7 @@ function(runtime_default_target)
   endforeach()
   foreach(component ${LLVM_RUNTIME_DISTRIBUTION_COMPONENTS})
     if(NOT ${component} IN_LIST SUB_COMPONENTS)
-      list(APPEND extra_targets ${component} install-${component} install-${component}-stripped)
+      list(APPEND extra_targets install-${component} install-${component}-stripped)
     endif()
   endforeach()