[llvm] [CMake] Make specifying invalid build type a fatal error (PR #72021)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/72021

This patch makes it so that specifying an invalid value for CMAKE_BUILD_TYPE is a fatal error. Having this simply as a warning has caused me (and probably others) a decent amount of headache. The check was present before, but was proposed to be modified to a warning in https://github.com/llvm/llvm-project/issues/60975 and changed to a warning in c75dbeda15c10424910ddc83a9ff7669776c19ac. This patch reenables that behavior to hopefully reduce frustration for people building LLVM in the common case while still allowing for alternative build types to be setup without needing to perform source modification through the addition of a CMake flag.

>From 36bec6d6e893f3be9e8d28759f2bb6de72ee0e86 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <agrossman154 at yahoo.com>
Date: Sat, 11 Nov 2023 01:19:11 -0800
Subject: [PATCH] [CMake] Make specifying invalid build type a fatal error

This patch makes it so that specifying an invalid value for
CMAKE_BUILD_TYPE is a fatal error. Having this simply as a warning has
caused me (and probably others) a decent amount of headache. The check
was present before, but was proposed to be modified to a warning in
https://github.com/llvm/llvm-project/issues/60975 and changed to a
warning in c75dbeda15c10424910ddc83a9ff7669776c19ac. This patch
reenables that behavior to hopefully reduce frustration for people
building LLVM in the common case while still allowing for alternative
build types to be setup without needing to perform source modification
through the addition of a CMake flag.
---
 llvm/CMakeLists.txt | 10 ++++++++--
 llvm/docs/CMake.rst |  5 +++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index 7ff3acd48304de7..1c983165b2ef003 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -392,9 +392,15 @@ endif()
 
 string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
 
+option(LLVM_ADDITIONAL_BUILD_TYPES "Additional build types that are allowed to be passed into CMAKE_BUILD_TYPE" "")
+
+set(ALLOWED_BUILD_TYPES DEBUG RELEASE RELWITHDEBINFO MINSIZEREL ${LLVM_ADDITIONAL_BUILD_TYPES})
+string (REPLACE ";" "|" ALLOWED_BUILD_TYPES_STRING "${ALLOWED_BUILD_TYPES}")
+string (TOUPPER "${ALLOWED_BUILD_TYPES_STRING}" uppercase_ALLOWED_BUILD_TYPES)
+
 if (CMAKE_BUILD_TYPE AND
-    NOT uppercase_CMAKE_BUILD_TYPE MATCHES "^(DEBUG|RELEASE|RELWITHDEBINFO|MINSIZEREL)$")
-  message(WARNING "Unknown value for CMAKE_BUILD_TYPE: ${CMAKE_BUILD_TYPE}")
+    NOT uppercase_CMAKE_BUILD_TYPE MATCHES "^(${uppercase_ALLOWED_BUILD_TYPES})$")
+  message(FATAL_ERROR "Unknown value for CMAKE_BUILD_TYPE: ${CMAKE_BUILD_TYPE}")
 endif()
 
 # LLVM_INSTALL_PACKAGE_DIR needs to be declared prior to adding the tools
diff --git a/llvm/docs/CMake.rst b/llvm/docs/CMake.rst
index 17b76996af85739..4b86eb9c01d26ba 100644
--- a/llvm/docs/CMake.rst
+++ b/llvm/docs/CMake.rst
@@ -321,6 +321,11 @@ enabled sub-projects. Nearly all of these variable names begin with
   enabled or not.  A version of LLVM built with ABI breaking checks
   is not ABI compatible with a version built without it.
 
+**LLVM_ADDITIONAL_BUILD_TYPES**:LIST
+  Adding a semicolon separated list of additional build types to this flag
+  allows for them to be specified as values in CMAKE_BUILD_TYPE without
+  encountering a fatal error during the configuration process.
+
 **LLVM_UNREACHABLE_OPTIMIZE**:BOOL
   This flag controls the behavior of `llvm_unreachable()` in release build
   (when assertions are disabled in general). When ON (default) then