[clang-tools-extra][cmake] Use `GNUInstallDirs` to support custom installation dirs.

This is the original patch in my GNUInstallDirs series, now last to merge as the final piece!

It arose as a new draft of D28234. I initially did the unorthodox thing of pushing to that when I wasn't the original author, but since I ended up

 - Using `GNUInstallDirs`, rather than mimicking it, as the original author was hesitant to do but others requested.

 - Converting all the packages, not just LLVM, effecting many more projects than LLVM itself.

I figured it was time to make a new revision.

I have used this patch series (and many back-ports) as the basis of https://github.com/NixOS/nixpkgs/pull/111487 for my distro (NixOS), which was merged last spring (2021). It looked like people were generally on board in D28234, but I make note of this here in case extra motivation is useful.

---

As pointed out in the original issue, a central tension is that LLVM already has some partial support for these sorts of things. Variables like `COMPILER_RT_INSTALL_PATH` have already been dealt with. Variables like `LLVM_LIBDIR_SUFFIX` however, will require further work, so that we may use `CMAKE_INSTALL_LIBDIR`.

These remaining items will be addressed in further patches. What is here is now rote and so we should get it out of the way before dealing more intricately with the remainder.

Reviewed By: #libunwind, #libc, #libc_abi, compnerd

Differential Revision: https://reviews.llvm.org/D99484

7 files changed, 10 insertions, 9 deletions

diff --git a/clang-tools-extra/CMakeLists.txt b/clang-tools-extra/CMakeLists.txt
index 2e73b6ba81d2..7b8274a97336 100644
--- a/clang-tools-extra/CMakeLists.txt
+++ b/clang-tools-extra/CMakeLists.txt
@@ -1,4 +1,5 @@
 include(CMakeDependentOption)
+include(GNUInstallDirs)
 
 option(CLANG_TIDY_ENABLE_STATIC_ANALYZER
   "Include static analyzer checks in clang-tidy" ON)
diff --git a/clang-tools-extra/clang-doc/tool/CMakeLists.txt b/clang-tools-extra/clang-doc/tool/CMakeLists.txt
index 7e7147886916..fb8317b27293 100644
--- a/clang-tools-extra/clang-doc/tool/CMakeLists.txt
+++ b/clang-tools-extra/clang-doc/tool/CMakeLists.txt
@@ -19,9 +19,9 @@ target_link_libraries(clang-doc
   )
 
 install(FILES ../assets/clang-doc-default-stylesheet.css
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-doc)
 
 install(FILES ../assets/index.js
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-doc)
diff --git a/clang-tools-extra/clang-include-fixer/find-all-symbols/tool/CMakeLists.txt b/clang-tools-extra/clang-include-fixer/find-all-symbols/tool/CMakeLists.txt
index 8f5509d22e24..e6926a0d5bd1 100644
--- a/clang-tools-extra/clang-include-fixer/find-all-symbols/tool/CMakeLists.txt
+++ b/clang-tools-extra/clang-include-fixer/find-all-symbols/tool/CMakeLists.txt
@@ -20,5 +20,5 @@ target_link_libraries(find-all-symbols
   )
 
 install(PROGRAMS run-find-all-symbols.py
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT find-all-symbols)
diff --git a/clang-tools-extra/clang-include-fixer/tool/CMakeLists.txt b/clang-tools-extra/clang-include-fixer/tool/CMakeLists.txt
index 3936ac1e8a5a..5b9e00ab87cd 100644
--- a/clang-tools-extra/clang-include-fixer/tool/CMakeLists.txt
+++ b/clang-tools-extra/clang-include-fixer/tool/CMakeLists.txt
@@ -21,8 +21,8 @@ target_link_libraries(clang-include-fixer
   )
 
 install(PROGRAMS clang-include-fixer.el
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-include-fixer)
 install(PROGRAMS clang-include-fixer.py
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-include-fixer)
diff --git a/clang-tools-extra/clang-tidy/CMakeLists.txt b/clang-tools-extra/clang-tidy/CMakeLists.txt
index 455645050d93..075e9f9909d6 100644
--- a/clang-tools-extra/clang-tidy/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/CMakeLists.txt
@@ -113,7 +113,7 @@ add_subdirectory(utils)
 
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY .
-    DESTINATION include/clang-tidy
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/clang-tidy"
     COMPONENT clang-tidy-headers
     FILES_MATCHING
     PATTERN "*.h"
diff --git a/clang-tools-extra/clang-tidy/tool/CMakeLists.txt b/clang-tools-extra/clang-tidy/tool/CMakeLists.txt
index ad3255b024fc..4b8c93801501 100644
--- a/clang-tools-extra/clang-tidy/tool/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/tool/CMakeLists.txt
@@ -52,9 +52,9 @@ target_link_libraries(clang-tidy
 
 
 install(PROGRAMS clang-tidy-diff.py
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-tidy)
 install(PROGRAMS run-clang-tidy.py
-  DESTINATION bin
+  DESTINATION "${CMAKE_INSTALL_BINDIR}"
   COMPONENT clang-tidy
   RENAME run-clang-tidy)
diff --git a/clang-tools-extra/modularize/CMakeLists.txt b/clang-tools-extra/modularize/CMakeLists.txt
index 4caae81c49b6..fb17e353c39f 100644
--- a/clang-tools-extra/modularize/CMakeLists.txt
+++ b/clang-tools-extra/modularize/CMakeLists.txt
@@ -23,5 +23,5 @@ clang_target_link_libraries(modularize
   )
 
 install(TARGETS modularize
-        RUNTIME DESTINATION bin
+        RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
         COMPONENT clang-extras)