meson: add sparse support

Do not use cgcc; instead, extract compilation commands from compile_commands.json
and invoke sparse directly.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Makefile

@@ -1261,6 +1261,7 @@ endif
 	$(call print-help,install,Install QEMU, documentation and tools)
 	$(call print-help,ctags/TAGS,Generate tags file for editors)
 	$(call print-help,cscope,Generate cscope index)
+	$(call print-help,sparse,Run sparse on the QEMU source)
 	@echo  ''
 	@$(if $(TARGET_DIRS), \
 		echo 'Architecture specific targets:'; \

configure

@@ -3058,7 +3058,7 @@ fi
 ##########################################
 # Sparse probe
 if test "$sparse" != "no" ; then
-  if has cgcc; then
+  if has sparse; then
     sparse=yes
   else
     if test "$sparse" = "yes" ; then
@@ -7859,11 +7859,7 @@ echo "QEMU_CFLAGS=$QEMU_CFLAGS" >> $config_host_mak
 echo "QEMU_CXXFLAGS=$QEMU_CXXFLAGS" >> $config_host_mak
 echo "QEMU_INCLUDES=$QEMU_INCLUDES" >> $config_host_mak
 if test "$sparse" = "yes" ; then
-  echo "CC           := REAL_CC=\"\$(CC)\" cgcc"       >> $config_host_mak
-  echo "CPP          := REAL_CC=\"\$(CPP)\" cgcc"      >> $config_host_mak
-  echo "CXX          := REAL_CC=\"\$(CXX)\" cgcc"      >> $config_host_mak
-  echo "HOST_CC      := REAL_CC=\"\$(HOST_CC)\" cgcc"  >> $config_host_mak
-  echo "QEMU_CFLAGS  += -Wbitwise -Wno-transparent-union -Wno-old-initializer -Wno-non-pointer-null" >> $config_host_mak
+  echo "SPARSE_CFLAGS = -Wbitwise -Wno-transparent-union -Wno-old-initializer -Wno-non-pointer-null" >> $config_host_mak
 fi
 echo "QEMU_LDFLAGS=$QEMU_LDFLAGS" >> $config_host_mak
 echo "LDFLAGS_NOPIE=$LDFLAGS_NOPIE" >> $config_host_mak

meson.build

@@ -25,6 +25,13 @@ if host_machine.system() == 'darwin'
   add_languages('objc', required: false, native: false)
 endif
 
+if 'SPARSE_CFLAGS' in config_host
+  run_target('sparse',
+             command: [find_program('scripts/check_sparse.py'),
+                       config_host['SPARSE_CFLAGS'].split(),
+                       'compile_commands.json'])
+endif
+
 configure_file(input: files('scripts/ninjatool.py'),
                output: 'ninjatool',
                configuration: config_host)

scripts/check_sparse.py

@@ -0,0 +1,25 @@
+#! /usr/bin/env python3
+
+# Invoke sparse based on the contents of compile_commands.json
+
+import json
+import subprocess
+import sys
+import shlex
+
+def extract_cflags(shcmd):
+    cflags = shlex.split(shcmd)
+    return [x for x in cflags
+            if x.startswith('-D') or x.startswith('-I') or x.startswith('-W')
+               or x.startswith('-std=')]
+
+cflags = sys.argv[1:-1]
+with open(sys.argv[-1], 'r') as fd:
+    compile_commands = json.load(fd)
+
+for cmd in compile_commands:
+    cmd = ['sparse'] + cflags + extract_cflags(cmd['command']) + [cmd['file']]
+    print(' '.join((shlex.quote(x) for x in cmd)))
+    r = subprocess.run(cmd)
+    if r.returncode != 0:
+        sys.exit(r.returncode)