Fix iOS combined feature for single architecture targets

If list of valid target architectures is empty for given SDK then there will
be no VALID_ARCHS build setting returned by Xcode. Return "" (empty string)
explicitly in this case. This may happens if CMAKE_IOS_INSTALL_COMBINED is ON
but only one architecture used in target.

Modules/CMakeIOSInstallCombined.cmake

@@ -52,7 +52,14 @@ function(_ios_install_combined_get_build_setting sdk variable resultvar)
   endif()
 
   if(NOT output MATCHES " ${variable} = ([^\n]*)")
-    message(FATAL_ERROR "${variable} not found.")
+    if("${variable}" STREQUAL "VALID_ARCHS")
+      # VALID_ARCHS may be unset by user for given SDK
+      # (e.g. for build without simulator).
+      set("${resultvar}" "" PARENT_SCOPE)
+      return()
+    else()
+      message(FATAL_ERROR "${variable} not found.")
+    endif()
   endif()
 
   set("${resultvar}" "${CMAKE_MATCH_1}" PARENT_SCOPE)
@@ -72,6 +79,9 @@ function(_ios_install_combined_get_valid_archs sdk resultvar)
   list(REMOVE_ITEM valid_archs "") # remove empty elements
   list(REMOVE_DUPLICATES valid_archs)
 
+  string(REPLACE ";" " " printable "${valid_archs}")
+  _ios_install_combined_message("Architectures (${sdk}): ${printable}")
+
   set("${resultvar}" "${valid_archs}" PARENT_SCOPE)
 endfunction()
 

Tests/RunCMake/XcodeProject/RunCMakeTest.cmake

@@ -97,6 +97,7 @@ if(NOT XCODE_VERSION VERSION_LESS 7)
 endif()
 
 if(NOT XCODE_VERSION VERSION_LESS 6)
+  # XcodeIOSInstallCombined
   set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/XcodeIOSInstallCombined-build)
   set(RunCMake_TEST_NO_CLEAN 1)
   set(RunCMake_TEST_OPTIONS
@@ -114,6 +115,7 @@ if(NOT XCODE_VERSION VERSION_LESS 6)
   unset(RunCMake_TEST_NO_CLEAN)
   unset(RunCMake_TEST_OPTIONS)
 
+  # XcodeIOSInstallCombinedPrune
   set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/XcodeIOSInstallCombinedPrune-build)
   set(RunCMake_TEST_NO_CLEAN 1)
   set(RunCMake_TEST_OPTIONS
@@ -130,4 +132,22 @@ if(NOT XCODE_VERSION VERSION_LESS 6)
   unset(RunCMake_TEST_BINARY_DIR)
   unset(RunCMake_TEST_NO_CLEAN)
   unset(RunCMake_TEST_OPTIONS)
+
+  # XcodeIOSInstallCombinedSingleArch
+  set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/XcodeIOSInstallCombinedSingleArch-build)
+  set(RunCMake_TEST_NO_CLEAN 1)
+  set(RunCMake_TEST_OPTIONS
+    "-DCMAKE_INSTALL_PREFIX:PATH=${RunCMake_TEST_BINARY_DIR}/_install"
+    "-DCMAKE_IOS_INSTALL_COMBINED=YES")
+
+  file(REMOVE_RECURSE "${RunCMake_TEST_BINARY_DIR}")
+  file(MAKE_DIRECTORY "${RunCMake_TEST_BINARY_DIR}")
+
+  run_cmake(XcodeIOSInstallCombinedSingleArch)
+  run_cmake_command(XcodeIOSInstallCombinedSingleArch-build ${CMAKE_COMMAND} --build .)
+  run_cmake_command(XcodeIOSInstallCombinedSingleArch-install ${CMAKE_COMMAND} --build . --target install)
+
+  unset(RunCMake_TEST_BINARY_DIR)
+  unset(RunCMake_TEST_NO_CLEAN)
+  unset(RunCMake_TEST_OPTIONS)
 endif()

Tests/RunCMake/XcodeProject/XcodeIOSInstallCombinedSingleArch-install-check.cmake

@@ -0,0 +1,25 @@
+function(verify_architecture file)
+  execute_process(
+    COMMAND xcrun lipo -info ${RunCMake_TEST_BINARY_DIR}/_install/${file}
+    OUTPUT_VARIABLE lipo_out
+    ERROR_VARIABLE lipo_err
+    RESULT_VARIABLE lipo_result)
+  if(NOT lipo_result EQUAL "0")
+    message(SEND_ERROR "lipo -info failed: ${lipo_err}")
+    return()
+  endif()
+
+  string(REGEX MATCHALL "is architecture: [^ \n\t]+" architecture "${lipo_out}")
+  string(REGEX REPLACE "is architecture: " "" actual "${architecture}")
+
+  set(expected armv7)
+
+  if(NOT actual STREQUAL expected)
+    message(SEND_ERROR
+      "The actual library architecture:\n ${actual} \n"
+      "which do not match expected ones:\n ${expected} \n"
+      "lipo output:\n${lipo_out}")
+  endif()
+endfunction()
+
+verify_architecture(lib/libfoo.dylib)

Tests/RunCMake/XcodeProject/XcodeIOSInstallCombinedSingleArch.cmake

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.3)
+
+project(XcodeIOSInstallCombinedSingleArch CXX)
+
+set(CMAKE_OSX_SYSROOT iphoneos)
+set(CMAKE_XCODE_ATTRIBUTE_CODE_SIGNING_REQUIRED "NO")
+set(CMAKE_XCODE_ATTRIBUTE_DEBUG_INFORMATION_FORMAT "dwarf")
+
+add_library(foo SHARED foo.cpp)
+install(TARGETS foo DESTINATION lib)
+
+set_target_properties(
+  foo
+  PROPERTIES
+  XCODE_ATTRIBUTE_ARCHS[sdk=iphoneos*] armv7
+  XCODE_ATTRIBUTE_VALID_ARCHS[sdk=iphoneos*] armv7
+  XCODE_ATTRIBUTE_ARCHS[sdk=iphonesimulator*] ""
+  XCODE_ATTRIBUTE_VALID_ARCHS[sdk=iphonesimulator*] ""
+)