[build] Update compile_commands.json when building

The compile_commands.json database is used by clangd to understand the
compilation settings of the project. Keep this up to date by making
ninja update it as part of the build, and have it depend on all build
and module files.

.gitignore

@@ -12,3 +12,4 @@ sysroot
 .peru
 __pycache__
 /venv
+compile_commands.json

configs/rules.ninja

@@ -76,3 +76,6 @@ rule strip
 
 rule touch
     command = touch $out
+
+rule compdb
+    command = ninja -t compdb > $out

scripts/bonnibel/module.py

@@ -141,7 +141,7 @@ class Module:
 
             inputs = []
             parse_deps = []
-            parse_dep = "${module_dir}/.parse_dep.phony"
+            parse_depfile = "${module_dir}/.parse_dep.phony"
 
             for start in self.sources:
                 source = start
@@ -150,7 +150,7 @@ class Module:
                     output = source.output
 
                     if source.action.parse_deps:
-                        oodeps = [parse_dep]
+                        oodeps = [parse_depfile]
                     else:
                         oodeps = []
 
@@ -177,7 +177,7 @@ class Module:
             build.newline()
             build.build(
                 rule = "touch",
-                outputs = [parse_dep],
+                outputs = [parse_depfile],
                 implicit = child_deps,
                 order_only = parse_deps,
             )

scripts/bonnibel/project.py

@@ -142,6 +142,8 @@ class Project:
                 build.default([out])
                 build.newline()
 
+            compdb = "${source_root}/compile_commands.json"
+
             build.rule("regen",
                 command = " ".join([str(root / 'configure')] + sys.argv[1:]),
                 description = "Regenerate build files",
@@ -156,6 +158,14 @@ class Project:
             for target in targets:
                 regen_implicits += target.depfiles
 
+            build.build(
+                rule = "compdb",
+                outputs = [compdb],
+                implicit = regen_implicits,
+                )
+            build.default([compdb])
+            build.newline()
+
             build.build(
                 rule = "regen",
                 outputs = ['build.ninja'],