Give more helpful error messages when files are missing

The current error message talks a lot about $srctree, but $srctree is
seldom the culprit in practice. More common is
'source "$(SOME_ENV_VAR)/foo"`, where SOME_ENV_VAR hasn't been set.

Include the complete 'source ...' line for missing Kconfig files, and
mention unset environment variables as a hint. Only mention $srctree
briefly.

Also shorten the message when a .config can't be a found a bit. This
message would usually only be seen when working directly with the
library.

2 files changed, 19 insertions, 26 deletions

diff --git a/kconfiglib.py b/kconfiglib.py
index aa27967..8c704e7 100644
--- a/kconfiglib.py
+++ b/kconfiglib.py
@@ -529,7 +529,6 @@ import platform
 import re
 import subprocess
 import sys
-import textwrap
 
 # File layout:
 #
@@ -1829,11 +1828,12 @@ class Kconfig(object):
                 # https://docs.python.org/3/reference/compound_stmts.html#the-try-statement
                 e = e2
 
-            raise _KconfigIOError(e, "\n" + textwrap.fill(
-                "Could not open '{}' ({}: {}){}".format(
-                    filename, errno.errorcode[e.errno], e.strerror,
-                    self._srctree_hint()),
-                80))
+            raise _KconfigIOError(e,
+                "Could not open '{}' ({}: {}). Check that the $srctree "
+                "environment variable ({}) is set correctly."
+                .format(filename, errno.errorcode[e.errno], e.strerror,
+                        "set to '{}'".format(self.srctree) if self.srctree
+                            else "unset or blank"))
 
     def _enter_file(self, full_filename, rel_filename):
         # Jumps to the beginning of a sourced Kconfig file, saving the previous
@@ -1873,7 +1873,7 @@ class Kconfig(object):
         for name, _ in self._include_path:
             if name == rel_filename:
                 raise KconfigError(
-                    "\n{}:{}: Recursive 'source' of '{}' detected. Check that "
+                    "\n{}:{}: recursive 'source' of '{}' detected. Check that "
                     "environment variables are set correctly.\n"
                     "Include path:\n{}"
                     .format(self._filename, self._linenr, rel_filename,
@@ -2628,11 +2628,15 @@ class Kconfig(object):
                     sorted(glob.iglob(os.path.join(self.srctree, pattern)))
 
                 if not filenames and t0 in _OBL_SOURCE_TOKENS:
-                    raise KconfigError("\n" + textwrap.fill(
-                        "{}:{}: '{}' does not exist{}".format(
-                            self._filename, self._linenr, pattern,
-                            self._srctree_hint()),
-                        80))
+                    raise KconfigError(
+                        "{}:{}: '{}' not found (in '{}'). Check that "
+                        "environment variables are set correctly (e.g. "
+                        "$srctree, which is {}). Also note that unset "
+                        "environment variables expand to the empty string."
+                        .format(self._filename, self._linenr, pattern,
+                                self._line.strip(),
+                                "set to '{}'".format(self.srctree)
+                                    if self.srctree else "unset or blank"))
 
                 for filename in filenames:
                     self._enter_file(
@@ -3659,17 +3663,6 @@ class Kconfig(object):
         if self._warn_for_redun_assign:
             self._warn(msg, filename, linenr)
 
-    def _srctree_hint(self):
-        # Hint printed when Kconfig files can't be found or .config files can't
-        # be opened
-
-        return ". Perhaps the $srctree environment variable ({}) " \
-               "is set incorrectly. Note that the current value of $srctree " \
-               "is saved when the Kconfig instance is created (for " \
-               "consistency and to cleanly separate instances)." \
-               .format("set to '{}'".format(self.srctree) if self.srctree
-                           else "unset or blank")
-
 class Symbol(object):
     """
     Represents a configuration symbol:
diff --git a/testsuite.py b/testsuite.py
index fbca36c..3301ed5 100644
--- a/testsuite.py
+++ b/testsuite.py
@@ -1059,7 +1059,7 @@ g
             Kconfig("tests/Krecursive1")
         except KconfigError as e:
             verify_equal(str(e), """
-tests/Krecursive2:1: Recursive 'source' of 'tests/Krecursive1' detected. Check that environment variables are set correctly.
+tests/Krecursive2:1: recursive 'source' of 'tests/Krecursive1' detected. Check that environment variables are set correctly.
 Include path:
 tests/Krecursive1:1
 tests/Krecursive2:1
@@ -1076,7 +1076,7 @@ tests/Krecursive2:1
         try:
             Kconfig("tests/Kmissingsource")
         except KconfigError as e:
-            if "does not exist" not in str(e):
+            if "not found" not in str(e):
                 fail("'source' with missing file raised wrong KconfigError")
         except:
             fail("'source' with missing file raised wrong exception")
@@ -1086,7 +1086,7 @@ tests/Krecursive2:1
         try:
             Kconfig("tests/Kmissingrsource")
         except KconfigError as e:
-            if "does not exist" not in str(e):
+            if "not found" not in str(e):
                 fail("'rsource' with missing file raised wrong KconfigError")
         except:
             fail("'rsource' with missing file raised wrong exception")