From: whitequark <whitequark@whitequark.org>
Date: Sat, 3 Aug 2019 18:52:24 +0000 (+0000)
Subject: hdl.dsl: reword m.If(~True) warning to be more clear.
X-Git-Tag: locally_working~54
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=99d205494a8930eac8f7da85a9558dd7e7b933f6;p=nmigen.git

hdl.dsl: reword m.If(~True) warning to be more clear.

Before this commit, it only suggested one thing (silencing it) and
that's wrong almost all of the time, so suggest the right thing
instead.
---

diff --git a/nmigen/hdl/dsl.py b/nmigen/hdl/dsl.py
index e090b09..9a7d598 100644
--- a/nmigen/hdl/dsl.py
+++ b/nmigen/hdl/dsl.py
@@ -171,8 +171,9 @@ class Module(_ModuleBuilderRoot, Elaboratable):
         if sign:
             warnings.warn("Signed values in If/Elif conditions usually result from inverting "
                           "Python booleans with ~, which leads to unexpected results: ~True is "
-                          "-2, which is truthful. "
-                          "(Silence this warning with `m.If(x)` → `m.If(x.bool())`.)",
+                          "-2, which is truthful. Replace `~flag` with `not flag`. (If this is "
+                          "a false positive, silence this warning with "
+                          "`m.If(x)` → `m.If(x.bool())`.)",
                           SyntaxWarning, stacklevel=4)
         return cond
 
diff --git a/nmigen/test/test_hdl_dsl.py b/nmigen/test/test_hdl_dsl.py
index 0ff7fef..1da5a6a 100644
--- a/nmigen/test/test_hdl_dsl.py
+++ b/nmigen/test/test_hdl_dsl.py
@@ -273,7 +273,8 @@ class DSLTestCase(FHDLTestCase):
         with self.assertWarns(SyntaxWarning,
                 msg="Signed values in If/Elif conditions usually result from inverting Python "
                     "booleans with ~, which leads to unexpected results: ~True is -2, which is "
-                    "truthful. (Silence this warning with `m.If(x)` → `m.If(x.bool())`.)"):
+                    "truthful. Replace `~flag` with `not flag`. (If this is a false positive, "
+                    "silence this warning with `m.If(x)` → `m.If(x.bool())`.)"):
             with m.If(~True):
                 pass
 
@@ -284,7 +285,8 @@ class DSLTestCase(FHDLTestCase):
         with self.assertWarns(SyntaxWarning,
                 msg="Signed values in If/Elif conditions usually result from inverting Python "
                     "booleans with ~, which leads to unexpected results: ~True is -2, which is "
-                    "truthful. (Silence this warning with `m.If(x)` → `m.If(x.bool())`.)"):
+                    "truthful. Replace `~flag` with `not flag`. (If this is a false positive, "
+                    "silence this warning with `m.If(x)` → `m.If(x.bool())`.)"):
             with m.Elif(~True):
                 pass