environment: guard state depending on a repository

In "environment.h" we have quite a lot of functions and variables that
either explicitly or implicitly depend on `the_repository`.

The implicit set of stateful declarations includes for example variables
which get populated when parsing a repository's Git configuration. This
set of variables is broken by design, as their state often depends on
the last repository config that has been parsed. So they may or may not
represent the state of `the_repository`.

Fixing that is quite a big undertaking, and later patches in this series
will demonstrate a solution for a first small set of those variables. So
for now, let's guard these with `USE_THE_REPOSITORY_VARIABLE` so that
callers are aware of the implicit dependency.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

compat/mingw.c

@@ -1,3 +1,5 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "../git-compat-util.h"
 #include "win32.h"
 #include <aclapi.h>

compat/win32/path-utils.c

@@ -1,3 +1,5 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "../../git-compat-util.h"
 #include "../../environment.h"
 

config.c

@@ -6,6 +6,8 @@
  *
  */
 
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "abspath.h"
 #include "advice.h"

environment.h

@@ -102,6 +102,28 @@ int use_optional_locks(void);
 const char *get_git_namespace(void);
 const char *strip_namespace(const char *namespaced_ref);
 
+/*
+ * TODO: All the below state either explicitly or implicitly relies on
+ * `the_repository`. We should eventually get rid of these and make the
+ * dependency on a repository explicit:
+ *
+ *   - `setup_git_env()` ideally shouldn't exist as it modifies global state,
+ *     namely the environment. The current process shouldn't ever access that
+ *     state via envvars though, but should instead consult a `struct
+ *     repository`. When spawning new processes, we would ideally also pass a
+ *     `struct repository` and then set up the environment variables for the
+ *     child process, only.
+ *
+ *   - `have_git_dir()` should not have to exist at all. Instead, we should
+ *     decide on whether or not we have a `struct repository`.
+ *
+ *   - All the global config variables should become tied to a repository. Like
+ *     this, we'd correctly honor repository-local configuration and be able to
+ *     distinguish configuration values from different repositories.
+ *
+ * Please do not add new global config variables here.
+ */
+# ifdef USE_THE_REPOSITORY_VARIABLE
 void setup_git_env(const char *git_dir);
 
 /*
@@ -213,4 +235,5 @@ extern const char *comment_line_str;
 extern char *comment_line_str_to_free;
 extern int auto_comment_line_char;
 
-#endif
+# endif /* USE_THE_REPOSITORY_VARIABLE */
+#endif /* ENVIRONMENT_H */

name-hash.c

@@ -5,6 +5,9 @@
  *
  * Copyright (C) 2008 Linus Torvalds
  */
+
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "environment.h"
 #include "gettext.h"

path.c

@@ -2,6 +2,8 @@
  * Utilities for paths and pathnames
  */
 
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "abspath.h"
 #include "environment.h"

preload-index.c

@@ -1,6 +1,9 @@
 /*
  * Copyright (C) 2008 Linus Torvalds
  */
+
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "pathspec.h"
 #include "dir.h"

prompt.c

@@ -1,3 +1,5 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "parse.h"
 #include "environment.h"

refs/files-backend.c

@@ -1,3 +1,5 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "../git-compat-util.h"
 #include "../copy.h"
 #include "../environment.h"

sparse-index.c

@@ -1,3 +1,5 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "environment.h"
 #include "gettext.h"

statinfo.c

@@ -1,3 +1,5 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "environment.h"
 #include "statinfo.h"

t/helper/test-path-utils.c

@@ -1,3 +1,5 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "test-tool.h"
 #include "abspath.h"
 #include "environment.h"

tree-diff.c

@@ -1,6 +1,9 @@
 /*
  * Helper functions for tree diff generation
  */
+
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "diff.h"
 #include "diffcore.h"

userdiff.c

@@ -1,3 +1,5 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "config.h"
 #include "userdiff.h"