BLD: change default of the allow-noblas option to true.

Having it set to false caused more disruption and complaints than
the silent performance regressions for `true` ever did.
So now that the dust has settled a bit on the transition to Meson,
go back to the more permissive default.

The warning that is emitted when BLAS and/or LAPACK are not found
is already much more visible than it was with distutils, so this
new situation is still an improvement over where we were until
1.25.x.

Closes gh-24703.

.github/workflows/linux_blas.yml

@@ -93,7 +93,7 @@ jobs:
       env:
         TERM: xterm-256color
       run:
-        spin build -- --werror
+        spin build -- --werror -Dallow-noblas=false
 
     - name: Check build-internal dependencies
       run:
@@ -135,15 +135,15 @@ jobs:
         pip install pytest hypothesis typing_extensions
 
     - name: Build (LP64)
-      run: spin build -- -Dblas=openblas -Dlapack=openblas -Ddisable-optimization=true
+      run: spin build -- -Dblas=openblas -Dlapack=openblas -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test
       run: spin test -- numpy/linalg
 
     - name: Build (ILP64)
       run: |
         rm -rf build
-        spin build -- -Duse-ilp64=true -Ddisable-optimization=true
+        spin build -- -Duse-ilp64=true -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test
       run: spin test -- numpy/linalg
@@ -170,15 +170,15 @@ jobs:
         pip install pytest hypothesis typing_extensions
 
     - name: Build
-      run: spin build -- -Ddisable-optimization=true
+      run: spin build -- -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test
       run: spin test -- numpy/linalg
 
     - name: Build (ILP64)
       run: |
         rm -rf build
-        spin build -- -Ddisable-optimization=true -Duse-ilp64=true
+        spin build -- -Ddisable-optimization=true -Duse-ilp64=true -Dallow-noblas=false
 
     - name: Test (ILP64)
       run: spin test -- numpy/linalg
@@ -205,7 +205,7 @@ jobs:
         sudo apt-get remove pkg-config
 
     - name: Build
-      run: spin build -- -Ddisable-optimization=true
+      run: spin build -- -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test
       run: spin test -j auto -- numpy/linalg
@@ -231,7 +231,7 @@ jobs:
 
     - name: Build
       run: |
-        spin build -- -Ddisable-optimization=true
+        spin build -- -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test
       run: |
@@ -307,7 +307,7 @@ jobs:
     - name: Build with defaults (LP64)
       run: |
         pkg-config --libs mkl-dynamic-lp64-seq  # check link flags
-        spin build -- -Ddisable-optimization=true
+        spin build -- -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test
       run: spin test -- numpy/linalg
@@ -316,7 +316,7 @@ jobs:
       run: |
         git clean -xdf > /dev/null
         pkg-config --libs mkl-dynamic-ilp64-seq
-        spin build -- -Duse-ilp64=true -Ddisable-optimization=true
+        spin build -- -Duse-ilp64=true -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test
       run: spin test -- numpy/linalg
@@ -328,7 +328,7 @@ jobs:
         rm mkl*.pc
         popd
         export MKLROOT=$Python3_ROOT_DIR
-        spin build -- -Ddisable-optimization=true
+        spin build -- -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test
       run: spin test -- numpy/linalg
@@ -363,7 +363,7 @@ jobs:
         pkg-config --cflags blis
 
     - name: Build
-      run: spin build -- -Dblas=blis -Ddisable-optimization=true
+      run: spin build -- -Dblas=blis -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test
       run: spin test -- numpy/linalg
@@ -388,7 +388,7 @@ jobs:
         sudo apt-get install libatlas-base-dev pkg-config
 
     - name: Build
-      run: spin build -- -Dblas=blas-atlas -Dlapack=lapack-atlas -Ddisable-optimization=true
+      run: spin build -- -Dblas=blas-atlas -Dlapack=lapack-atlas -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test
       run: spin test -- numpy/linalg

.github/workflows/macos.yml

@@ -84,7 +84,7 @@ jobs:
       shell: bash -l {0}
       run: |
         conda activate numpy-dev
-        CC="ccache $CC" spin build -j2
+        CC="ccache $CC" spin build -j2 -- -Dallow-noblas=false
 
     - name: Run test suite (full)
       shell: bash -l {0}
@@ -123,14 +123,14 @@ jobs:
         pip install pytest pytest-xdist hypothesis
 
     - name: Build against Accelerate (LP64)
-      run: spin build -- -Ddisable-optimization=true
+      run: spin build -- -Ddisable-optimization=true -Dallow-noblas=false
 
     - name: Test (linalg only)
       run: spin test -j2 -- numpy/linalg
 
     - name: Build NumPy against Accelerate (ILP64)
       run: |
-        spin build -- -Duse-ilp64=true
+        spin build -- -Duse-ilp64=true -Dallow-noblas=false
 
     - name: Test (fast tests)
       run: spin test -j2

meson_options.txt

@@ -2,7 +2,7 @@ option('blas', type: 'string', value: 'auto',
         description: 'Option for BLAS library selection. By default, try to find any in the order given by `blas-order`')
 option('lapack', type: 'string', value: 'auto',
         description: 'Option for LAPACK library selection. By default, try to find any in the order given by `lapack-order`')
-option('allow-noblas', type: 'boolean', value: false,
+option('allow-noblas', type: 'boolean', value: true,
         description: 'If set to true, allow building with (slow!) internal fallback routines')
 option('blas-order', type: 'array',
         value: ['mkl', 'accelerate', 'openblas', 'flexiblas', 'blis', 'blas'])

pyproject.toml

@@ -153,7 +153,7 @@ tracker = "https://github.com/numpy/numpy/issues"
 skip = "cp36-* cp37-* cp-38* pp37-* pp38-* *-manylinux_i686 *_ppc64le *_s390x"
 build-verbosity = "3"
 before-build = "bash {project}/tools/wheels/cibw_before_build.sh {project}"
-config-settings = "setup-args=-Duse-ilp64=true setup-args=-Dblas=openblas setup-args=-Dlapack=openblas setup-args=-Dblas-symbol-suffix=64_"
+config-settings = "setup-args=-Duse-ilp64=true setup-args=-Dblas=openblas setup-args=-Dlapack=openblas setup-args=-Dblas-symbol-suffix=64_ setup-args=-Dallow-noblas=false"
 # meson has a hard dependency on ninja, and we need meson to build
 # c-extensions in tests. There is a ninja PyPI package used in
 # build_requirements.txt for macOS, windows, linux but it cannot be in