Unset comiler flags for before_all

Author: oscarbenjamin

bin/cibw_before_all_pyodide.sh

@@ -13,6 +13,13 @@ fi
 
 mkdir -p "$WASM_LIBRARY_DIR"
 
-export CFLAGS="-fPIC ${CFLAGS:-}"
+# The Pyodide cibuildwheel environment for building python-flint itself sets
+# include/library flags that reference libgmp/libmpfr/libflint. Those libraries
+# do not exist yet while bootstrapping the static dependencies here, so letting
+# them leak into configure would break link tests such as "does the C compiler
+# work?" for GMP. Use a minimal environment for the bootstrap step.
+unset PKG_CONFIG_PATH
+unset LDFLAGS
+export CFLAGS="-fPIC"
 
 "$SCRIPT_DIR/pyodide_build_dependencies.sh" --wasm-library-dir "$WASM_LIBRARY_DIR"