Always mention explicit export when relevant (#13925)

Related to #13917 and #13908. This handles situations involving
per-module re-exports correctly / is consistent with the error you'd get
with attribute access.

mypy/semanal.py

@@ -2346,10 +2346,9 @@ def report_missing_module_attribute(
         # Suggest alternatives, if any match is found.
         module = self.modules.get(import_id)
         if module:
-            if not self.options.implicit_reexport and source_id in module.names.keys():
+            if source_id in module.names.keys() and not module.names[source_id].module_public:
                 message = (
-                    'Module "{}" does not explicitly export attribute "{}"'
-                    "; implicit reexport disabled".format(import_id, source_id)
+                    f'Module "{import_id}" does not explicitly export attribute "{source_id}"'
                 )
             else:
                 alternatives = set(module.names.keys()).difference({source_id})

test-data/unit/check-flags.test

@@ -1613,7 +1613,7 @@ a = 5
 [file other_module_2.py]
 from other_module_1 import a
 [out]
-main:2: error: Module "other_module_2" does not explicitly export attribute "a"; implicit reexport disabled
+main:2: error: Module "other_module_2" does not explicitly export attribute "a"
 
 [case testNoImplicitReexportRespectsAll]
 # flags: --no-implicit-reexport
@@ -1627,7 +1627,7 @@ from other_module_1 import a, b
 __all__ = ('b',)
 [builtins fixtures/tuple.pyi]
 [out]
-main:2: error: Module "other_module_2" does not explicitly export attribute "a"; implicit reexport disabled
+main:2: error: Module "other_module_2" does not explicitly export attribute "a"
 
 [case testNoImplicitReexportStarConsideredExplicit]
 # flags: --no-implicit-reexport
@@ -1643,7 +1643,7 @@ __all__ = ('b',)
 
 [case testNoImplicitReexportGetAttr]
 # flags: --no-implicit-reexport --python-version 3.7
-from other_module_2 import a  # E: Module "other_module_2" does not explicitly export attribute "a"; implicit reexport disabled
+from other_module_2 import a  # E: Module "other_module_2" does not explicitly export attribute "a"
 [file other_module_1.py]
 from typing import Any
 def __getattr__(name: str) -> Any: ...
@@ -1661,7 +1661,7 @@ attr_2 = 6
 [file other_module_2.py]
 from other_module_1 import attr_1, attr_2
 [out]
-main:2: error: Module "other_module_2" does not explicitly export attribute "attr_1"; implicit reexport disabled
+main:2: error: Module "other_module_2" does not explicitly export attribute "attr_1"
 
 [case testNoImplicitReexportMypyIni]
 # flags: --config-file tmp/mypy.ini
@@ -1679,7 +1679,7 @@ implicit_reexport = True
 \[mypy-other_module_2]
 implicit_reexport = False
 [out]
-main:2: error: Module "other_module_2" has no attribute "a"
+main:2: error: Module "other_module_2" does not explicitly export attribute "a"
 
 
 [case testNoImplicitReexportPyProjectTOML]
@@ -1700,7 +1700,7 @@ module = 'other_module_2'
 implicit_reexport = false
 
 [out]
-main:2: error: Module "other_module_2" has no attribute "a"
+main:2: error: Module "other_module_2" does not explicitly export attribute "a"
 
 
 [case testImplicitAnyOKForNoArgs]

test-data/unit/check-modules.test

@@ -1787,8 +1787,8 @@ m = n  # E: Cannot assign multiple modules to name "m" without explicit "types.M
 [builtins fixtures/module.pyi]
 
 [case testNoReExportFromStubs]
-from stub import Iterable  # E: Module "stub" has no attribute "Iterable"
-from stub import D  # E: Module "stub" has no attribute "D"
+from stub import Iterable  # E: Module "stub" does not explicitly export attribute "Iterable"
+from stub import D  # E: Module "stub" does not explicitly export attribute "D"
 from stub import C
 
 c = C()
@@ -1884,7 +1884,7 @@ class C:
 from util import mod
 reveal_type(mod)  # N: Revealed type is "def () -> package.mod.mod"
 
-from util import internal_detail  # E: Module "util" has no attribute "internal_detail"
+from util import internal_detail  # E: Module "util" does not explicitly export attribute "internal_detail"
 
 [file package/__init__.pyi]
 from .mod import mod as mod
@@ -1899,7 +1899,7 @@ from package import mod as internal_detail
 [builtins fixtures/module.pyi]
 
 [case testNoReExportUnrelatedModule]
-from mod2 import unrelated  # E: Module "mod2" has no attribute "unrelated"
+from mod2 import unrelated  # E: Module "mod2" does not explicitly export attribute "unrelated"
 
 [file mod1/__init__.pyi]
 [file mod1/unrelated.pyi]
@@ -1910,7 +1910,7 @@ from mod1 import unrelated
 [builtins fixtures/module.pyi]
 
 [case testNoReExportUnrelatedSiblingPrefix]
-from pkg.unrel import unrelated  # E: Module "pkg.unrel" has no attribute "unrelated"
+from pkg.unrel import unrelated  # E: Module "pkg.unrel" does not explicitly export attribute "unrelated"
 
 [file pkg/__init__.pyi]
 [file pkg/unrelated.pyi]
@@ -1922,7 +1922,7 @@ from pkg import unrelated
 
 [case testNoReExportChildStubs]
 import mod
-from mod import C, D  # E: Module "mod" has no attribute "C"
+from mod import C, D  # E: Module "mod" does not explicitly export attribute "C"
 
 reveal_type(mod.x)  # N: Revealed type is "mod.submod.C"
 mod.C  # E: "Module mod" does not explicitly export attribute "C"
@@ -1940,7 +1940,7 @@ class D:
 [builtins fixtures/module.pyi]
 
 [case testNoReExportNestedStub]
-from stub import substub  # E: Module "stub" has no attribute "substub"
+from stub import substub  # E: Module "stub" does not explicitly export attribute "substub"
 
 [file stub.pyi]
 import substub
@@ -2887,10 +2887,10 @@ CustomDict = TypedDict(
 [builtins fixtures/tuple.pyi]
 
 [case testNoReExportFromMissingStubs]
-from stub import a  # E: Module "stub" has no attribute "a"
+from stub import a  # E: Module "stub" does not explicitly export attribute "a"
 from stub import b
 from stub import c  # E: Module "stub" has no attribute "c"
-from stub import d  # E: Module "stub" has no attribute "d"
+from stub import d  # E: Module "stub" does not explicitly export attribute "d"
 
 [file stub.pyi]
 from mystery import a, b as b, c as d