From 1dd9314f4d5c466427e6683cabc6bf15406f48ef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Erik=20Nordstr=C3=B6m?= <erik@timescale.com>
Date: Thu, 28 May 2020 12:37:16 +0200
Subject: [PATCH] Improve linting support with clang-tidy

This change replaces the existing `clang-tidy` linter target with
CMake's built-in support for it. The old way of invoking the linter
relied on the `run-clang-tidy` wrapper script, which is not installed
by default on some platforms. Discovery of the `clang-tidy` tool has
also been improved to work with more installation locations.

As a result, linting now happens at compile time and is enabled
automatically when `clang-tidy` is installed and found.

In enabling `clang-tidy`, several non-trivial issues were discovered
in compression-related code. These might be false positives, but,
until a proper solution can be found, "warnings-as-errors" have been
disabled for that code to allow compilation to succeed with the linter
enabled.
---
 CMakeLists.txt                  | 42 +++++++++++++++++++++++----------
 tsl/src/compression/.clang-tidy |  8 +++++++
 2 files changed, 37 insertions(+), 13 deletions(-)
 create mode 100644 tsl/src/compression/.clang-tidy

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a426748a8..a3efd3a0c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -68,6 +68,9 @@ set(PROJECT_INSTALL_METHOD source CACHE STRING "Specify what install platform th
 is built for")
 message(STATUS "Install method is '${PROJECT_INSTALL_METHOD}'")
 
+# Build compilation database by default
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
 # Code coverage is optional and OFF by default
 option(CODECOVERAGE "Enable code coverage for the build" OFF)
 
@@ -251,6 +254,12 @@ install(
 # in standard installation paths.
 find_program(CLANG_FORMAT
   NAMES clang-format-8 clang-format-7 clang-format
+  PATHS
+  /usr/bin
+  /usr/local/bin
+  /usr/local/opt/
+  /usr/local/opt/llvm/bin
+  /opt/bin
   DOC "The path to clang-format")
 
 if (CLANG_FORMAT)
@@ -287,20 +296,27 @@ else()
   )
 endif ()
 
-find_program(RUN_CLANG_TIDY run-clang-tidy DOC "The path to run-clang-tidy")
+# Linter support via clang-tidy. Enabled by default.
+option(LINTER "Enable linter support using clang-tidy (default ON)" ON)
 
-if(RUN_CLANG_TIDY)
-  message(STATUS "Found clang-tidy at ${RUN_CLANG_TIDY}")
-  if(CMAKE_EXPORT_COMPILE_COMMANDS)
-    add_custom_target(clang-tidy COMMAND ${RUN_CLANG_TIDY} -quiet)
-  else()
-    message(WARNING "You need to add -DCMAKE_EXPORT_COMPILE_COMMANDS=ON to use clang-tidy")
-    add_custom_target(clang-tidy
-      COMMAND ${CMAKE_COMMAND} -E echo "clang-tidy found but -DCMAKE_EXPORT_COMPILE_COMMAND was not set")
-  endif()
-else()
-  message(WARNING "Did not find clang-tidy, not defining clang-tidy target.")
-endif()
+if (LINTER)
+  find_program(CLANG_TIDY
+    clang-tidy
+    PATHS
+    /usr/bin
+    /usr/local/bin
+    /usr/local/opt/
+    /usr/local/opt/llvm/bin
+    /opt/bin
+    DOC "The path to the clang-tidy linter")
+
+  if (CLANG_TIDY)
+    message(STATUS "Linter support (clang-tidy) enabled")
+    set(CMAKE_C_CLANG_TIDY "${CLANG_TIDY};--quiet")
+  else ()
+    message(STATUS "Install clang-tidy to enable code linting")
+  endif (CLANG_TIDY)
+endif (LINTER)
 
 option(USE_OPENSSL "Enable use of OpenSSL if available" ON)
 option(SEND_TELEMETRY_DEFAULT "The default value for whether to send telemetry" ON)
diff --git a/tsl/src/compression/.clang-tidy b/tsl/src/compression/.clang-tidy
new file mode 100644
index 000000000..77b1143ff
--- /dev/null
+++ b/tsl/src/compression/.clang-tidy
@@ -0,0 +1,8 @@
+# Disable warnings as errors on compression code since it currently
+# doesn't pass those tests
+---
+Checks:          '-*,clang-analyzer-core.*,clang-diagnostic-*'
+WarningsAsErrors: 'clang-analyzer-unix.*'
+HeaderFilterRegex: ''
+AnalyzeTemporaryDtors: false
+...