Declare LLVM 21 as "officially" supported (#1254)

Author: Akuli

.github/workflows/linux.yml

@@ -26,6 +26,7 @@ jobs:
           - { llvm-version: 18, opt-level: '-O1' }
           - { llvm-version: 19, opt-level: '-O1' }
           # Latest version: all opt levels
+          # TODO: LLVM 21 is not available from apt yet.
           - { llvm-version: 20, opt-level: '-O0' }
           - { llvm-version: 20, opt-level: '-O1' }
           - { llvm-version: 20, opt-level: '-O2' }

.github/workflows/macos.yml

@@ -65,11 +65,12 @@ jobs:
           - { llvm-version: 17, opt-level: '-O1' }
           - { llvm-version: 18, opt-level: '-O1' }
           - { llvm-version: 19, opt-level: '-O1' }
-          # Latest version: all opt levels
-          - { llvm-version: 20, opt-level: '-O0' }
           - { llvm-version: 20, opt-level: '-O1' }
-          - { llvm-version: 20, opt-level: '-O2' }
-          - { llvm-version: 20, opt-level: '-O3' }
+          # Latest version: all opt levels
+          - { llvm-version: 21, opt-level: '-O0' }
+          - { llvm-version: 21, opt-level: '-O1' }
+          - { llvm-version: 21, opt-level: '-O2' }
+          - { llvm-version: 21, opt-level: '-O3' }
     steps:
       - uses: actions/checkout@v6
         with:

.github/workflows/valgrind.yml

@@ -53,6 +53,7 @@ jobs:
           - { llvm-version: 18, opt-level: '-O1' }
           - { llvm-version: 19, opt-level: '-O1' }
           # Latest version: all opt levels
+          # TODO: LLVM 21 is not available from apt yet.
           - { llvm-version: 20, opt-level: '-O0' }
           - { llvm-version: 20, opt-level: '-O1' }
           - { llvm-version: 20, opt-level: '-O2' }

Makefile.posix

@@ -2,10 +2,11 @@
 # On macos, brew installs LLVM to a weird place in /usr/local/
 # On NetBSD, llvm-config is unversioned.
 # On any platform, it can be set as environment variable or make parameter.
-#
-# TODO: Move LLVM 21 to the top when officially supported
 LLVM_CONFIG != \
 	command -v "$(LLVM_CONFIG)" \
+	|| command -v llvm-config-21 \
+	|| command -v /usr/local/opt/llvm@21/bin/llvm-config \
+	|| command -v /opt/homebrew/opt/llvm@21/bin/llvm-config \
 	|| command -v llvm-config-20 \
 	|| command -v /usr/local/opt/llvm@20/bin/llvm-config \
 	|| command -v /opt/homebrew/opt/llvm@20/bin/llvm-config \
@@ -24,15 +25,12 @@ LLVM_CONFIG != \
 	|| command -v llvm-config-15 \
 	|| command -v /usr/local/opt/llvm@15/bin/llvm-config \
 	|| command -v /opt/homebrew/opt/llvm@15/bin/llvm-config \
-	|| command -v llvm-config \
-	|| command -v llvm-config-21 \
-	|| command -v /usr/local/opt/llvm@21/bin/llvm-config \
-	|| command -v /opt/homebrew/opt/llvm@21/bin/llvm-config \
+	|| command -v llvm-config
 
 all: jou
 
 config.jou: Makefile.posix
-	@v=`$(LLVM_CONFIG) --version`; case "$$v" in 15.*|16.*|17.*|18.*|19.*|20.*) ;; 21.*) ;; *) echo "Error: Found unsupported LLVM version $$v. Only LLVM 15,16,17,18,19,20 are supported."; exit 1; esac
+	@v=`$(LLVM_CONFIG) --version`; case "$$v" in 15.*|16.*|17.*|18.*|19.*|20.*|21.*) ;; *) echo "Error: Found unsupported LLVM version $$v. Only LLVM 15,16,17,18,19,20,21 are supported."; exit 1; esac
 	echo '# auto-generated by Makefile.posix' > config.jou
 	echo '' >> config.jou
 	printf 'link "%s"\n' `$(LLVM_CONFIG) --ldflags --libs` >> config.jou

README.md

@@ -92,6 +92,7 @@ The instructions for developing Jou are in [CONTRIBUTING.md](CONTRIBUTING.md).
     ```
     Let me know if you use a distro that doesn't have `apt`,
     and you need help with this step.
+    See also the list of supported LLVM/clang versions below.
 2. Download and compile Jou.
     ```
     $ git clone https://github.com/Akuli/jou
@@ -126,8 +127,6 @@ These LLVM/clang versions are supported:
 - LLVM 18 with clang 18
 - LLVM 19 with clang 19
 - LLVM 20 with clang 20
-
-These versions are not covered by automated tests but seem to work anyway:
 - LLVM 21 with clang 21
 
 By default, the `make` command picks the latest available version.
@@ -157,6 +156,7 @@ $ LLVM_CONFIG=llvm-config-15 make
     - `llvm@18`
     - `llvm@19`
     - `llvm@20`
+    - `llvm@21`
 2. Install Python if you don't have it already.
     Any reasonably new version will work.
 3. Download and compile Jou.