CMake: Disable installation when using bundled third party libraries

If gRPC is not getting its (link-time) dependencies from the system, it
should not be attempting installation.

CMakeLists.txt

@@ -48,11 +48,12 @@ project(${PACKAGE_NAME} C CXX)
 # Options
 option(gRPC_BUILD_TESTS "Build tests" OFF)
 
-if (NOT MSVC)
-  set(gRPC_INSTALL ON CACHE BOOL "Generate installation target")
-else()
-  set(gRPC_INSTALL OFF CACHE BOOL "Generate installation target")
+set(gRPC_INSTALL_default ON)
+if (MSVC)
+    set(gRPC_INSTALL_default OFF)
 endif()
+set(gRPC_INSTALL ${gRPC_INSTALL_default} CACHE BOOL
+    "Generate installation target: gRPC_ZLIB_PROVIDER, gRPC_CARES_PROVIDER, gRPC_SSL_PROVIDER and gRPC_PROTOBUF_PROVIDER must all be \"package\"")
 
 set(gRPC_ZLIB_PROVIDER "module" CACHE STRING "Provider of zlib library")
 set_property(CACHE gRPC_ZLIB_PROVIDER PROPERTY STRINGS "module" "package")
@@ -118,6 +119,10 @@ if("${gRPC_ZLIB_PROVIDER}" STREQUAL "module")
   else()
       message(WARNING "gRPC_ZLIB_PROVIDER is \"module\" but ZLIB_ROOT_DIR is wrong")
   endif()
+  if(gRPC_INSTALL)
+    message(WARNING "gRPC_INSTALL will be forced to FALSE because gRPC_ZLIB_PROVIDER is \"module\"")
+    set(gRPC_INSTALL FALSE)
+  endif()
 elseif("${gRPC_ZLIB_PROVIDER}" STREQUAL "package")
   find_package(ZLIB)
   if(TARGET ZLIB::ZLIB)
@@ -149,6 +154,10 @@ if("${gRPC_CARES_PROVIDER}" STREQUAL "module")
   else()
     message(WARNING "gRPC_CARES_PROVIDER is \"module\" but CARES_ROOT_DIR is wrong")
   endif()
+  if(gRPC_INSTALL)
+    message(WARNING "gRPC_INSTALL will be forced to FALSE because gRPC_CARES_PROVIDER is \"module\"")
+    set(gRPC_INSTALL FALSE)
+  endif()
 elseif("${gRPC_CARES_PROVIDER}" STREQUAL "package")
   find_package(c-ares CONFIG)
   if(TARGET c-ares::cares)
@@ -183,6 +192,10 @@ if("${gRPC_PROTOBUF_PROVIDER}" STREQUAL "module")
   else()
       message(WARNING "gRPC_PROTOBUF_PROVIDER is \"module\" but PROTOBUF_ROOT_DIR is wrong")
   endif()
+  if(gRPC_INSTALL)
+    message(WARNING "gRPC_INSTALL will be forced to FALSE because gRPC_PROTOBUF_PROVIDER is \"module\"")
+    set(gRPC_INSTALL FALSE)
+  endif()
 elseif("${gRPC_PROTOBUF_PROVIDER}" STREQUAL "package")
   find_package(protobuf CONFIG)
   if(protobuf_FOUND)
@@ -216,6 +229,10 @@ if("${gRPC_SSL_PROVIDER}" STREQUAL "module")
   else()
       message(WARNING "gRPC_SSL_PROVIDER is \"module\" but BORINGSSL_ROOT_DIR is wrong")
   endif()
+  if(gRPC_INSTALL)
+    message(WARNING "gRPC_INSTALL will be forced to FALSE because gRPC_SSL_PROVIDER is \"module\"")
+    set(gRPC_INSTALL FALSE)
+  endif()
 elseif("${gRPC_SSL_PROVIDER}" STREQUAL "package")
   find_package(OpenSSL)
   if(TARGET OpenSSL::SSL)

templates/CMakeLists.txt.template

@@ -92,11 +92,12 @@
   # Options
   option(gRPC_BUILD_TESTS "Build tests" OFF)
 
-  if (NOT MSVC)
-    set(gRPC_INSTALL ON CACHE BOOL "Generate installation target")
-  else()
-    set(gRPC_INSTALL OFF CACHE BOOL "Generate installation target")
+  set(gRPC_INSTALL_default ON)
+  if (MSVC)
+      set(gRPC_INSTALL_default OFF)
   endif()
+  set(gRPC_INSTALL <%text>${gRPC_INSTALL_default}</%text> CACHE BOOL
+      "Generate installation target: gRPC_ZLIB_PROVIDER, gRPC_CARES_PROVIDER, gRPC_SSL_PROVIDER and gRPC_PROTOBUF_PROVIDER must all be \"package\"")
 
   set(gRPC_ZLIB_PROVIDER "module" CACHE STRING "Provider of zlib library")
   set_property(CACHE gRPC_ZLIB_PROVIDER PROPERTY STRINGS "module" "package")
@@ -163,6 +164,10 @@
     else()
         message(WARNING "gRPC_ZLIB_PROVIDER is \"module\" but ZLIB_ROOT_DIR is wrong")
     endif()
+    if(gRPC_INSTALL)
+      message(WARNING "gRPC_INSTALL will be forced to FALSE because gRPC_ZLIB_PROVIDER is \"module\"")
+      set(gRPC_INSTALL FALSE)
+    endif()
   elseif("<%text>${gRPC_ZLIB_PROVIDER}</%text>" STREQUAL "package")
     find_package(ZLIB)
     if(TARGET ZLIB::ZLIB)
@@ -194,6 +199,10 @@
     else()
       message(WARNING "gRPC_CARES_PROVIDER is \"module\" but CARES_ROOT_DIR is wrong")
     endif()
+    if(gRPC_INSTALL)
+      message(WARNING "gRPC_INSTALL will be forced to FALSE because gRPC_CARES_PROVIDER is \"module\"")
+      set(gRPC_INSTALL FALSE)
+    endif()
   elseif("<%text>${gRPC_CARES_PROVIDER}</%text>" STREQUAL "package")
     find_package(c-ares CONFIG)
     if(TARGET c-ares::cares)
@@ -228,6 +237,10 @@
     else()
         message(WARNING "gRPC_PROTOBUF_PROVIDER is \"module\" but PROTOBUF_ROOT_DIR is wrong")
     endif()
+    if(gRPC_INSTALL)
+      message(WARNING "gRPC_INSTALL will be forced to FALSE because gRPC_PROTOBUF_PROVIDER is \"module\"")
+      set(gRPC_INSTALL FALSE)
+    endif()
   elseif("<%text>${gRPC_PROTOBUF_PROVIDER}</%text>" STREQUAL "package")
     find_package(protobuf CONFIG)
     if(protobuf_FOUND)
@@ -261,6 +274,10 @@
     else()
         message(WARNING "gRPC_SSL_PROVIDER is \"module\" but BORINGSSL_ROOT_DIR is wrong")
     endif()
+    if(gRPC_INSTALL)
+      message(WARNING "gRPC_INSTALL will be forced to FALSE because gRPC_SSL_PROVIDER is \"module\"")
+      set(gRPC_INSTALL FALSE)
+    endif()
   elseif("<%text>${gRPC_SSL_PROVIDER}</%text>" STREQUAL "package")
     find_package(OpenSSL)
     if(TARGET OpenSSL::SSL)