[lit] Prevent hang when lit sees non-ASCII characters

As per discussion in D69207, have lit ignore UnicodeDecodeErrors
when running with python 2 in an ASCII shell.

Differential Revision: https://reviews.llvm.org/D82754

llvm/utils/lit/lit/display.py

@@ -86,7 +86,10 @@ def print_result(self, test):
                                      errors="replace")
                 except UnicodeDecodeError:
                     pass
-                out = out.decode(encoding=sys.stdout.encoding)
+                # Python 2 can raise UnicodeDecodeError here too in cases
+                # where the stdout encoding is ASCII. Ignore decode errors
+                # in this case.
+                out = out.decode(encoding=sys.stdout.encoding, errors="ignore")
             print(out)
             print("*" * 20)
 

llvm/utils/lit/tests/shtest-shell.py

@@ -6,6 +6,14 @@
 # RUN: cat %t.out
 # RUN: FileCheck --input-file %t.out %s
 #
+# Test again in non-UTF shell to catch potential errors with python 2 seen
+# on stdout-encoding.txt
+# RUN: env PYTHONIOENCODING=ascii not %{lit} -j 1 -a %{inputs}/shtest-shell > %t.ascii.out
+# FIXME: Temporarily dump test output so we can debug failing tests on
+# buildbots.
+# RUN: cat %t.ascii.out
+# RUN: FileCheck --input-file %t.ascii.out %s
+#
 # END.
 
 # CHECK: -- Testing:
@@ -64,7 +72,7 @@
 # CHECK-NEXT: @@
 # CHECK-NEXT: {{^ .f.o.o.$}}
 # CHECK-NEXT: {{^-.b.a.r.$}}
-# CHECK-NEXT: {{^\+.b.a.r..}}
+# CHECK-NEXT: {{^\+.b.a.r.}}
 # CHECK-NEXT: {{^ .b.a.z.$}}
 # CHECK: error: command failed with exit status: 1
 # CHECK: $ "true"
@@ -78,7 +86,7 @@
 # CHECK-NEXT: -bar
 # CHECK-NEXT: -baz
 # CHECK-NEXT: {{^\+.f.o.o.$}}
-# CHECK-NEXT: {{^\+.b.a.r..}}
+# CHECK-NEXT: {{^\+.b.a.r.}}
 # CHECK-NEXT: {{^\+.b.a.z.$}}
 # CHECK: error: command failed with exit status: 1
 # CHECK: $ "true"
@@ -89,7 +97,7 @@
 # CHECK-NEXT: +++
 # CHECK-NEXT: @@
 # CHECK-NEXT: {{^\-.f.o.o.$}}
-# CHECK-NEXT: {{^\-.b.a.r..}}
+# CHECK-NEXT: {{^\-.b.a.r.}}
 # CHECK-NEXT: {{^\-.b.a.z.$}}
 # CHECK-NEXT: +foo
 # CHECK-NEXT: +bar
@@ -116,7 +124,7 @@
 # CHECK-NEXT: @@
 # CHECK-NEXT: {{^ .f.o.o.$}}
 # CHECK-NEXT: {{^-.b.a.r.$}}
-# CHECK-NEXT: {{^\+.b.a.r..}}
+# CHECK-NEXT: {{^\+.b.a.r.}}
 # CHECK-NEXT: {{^ .b.a.z.$}}
 # CHECK: error: command failed with exit status: 1
 # CHECK: $ "true"
@@ -132,7 +140,7 @@
 # CHECK-NEXT: -bar
 # CHECK-NEXT: -baz
 # CHECK-NEXT: {{^\+.f.o.o.$}}
-# CHECK-NEXT: {{^\+.b.a.r..}}
+# CHECK-NEXT: {{^\+.b.a.r.}}
 # CHECK-NEXT: {{^\+.b.a.z.$}}
 # CHECK: error: command failed with exit status: 1
 # CHECK: $ "true"
@@ -143,7 +151,7 @@
 # CHECK-NEXT: +++
 # CHECK-NEXT: @@
 # CHECK-NEXT: {{^\-.f.o.o.$}}
-# CHECK-NEXT: {{^\-.b.a.r..}}
+# CHECK-NEXT: {{^\-.b.a.r.}}
 # CHECK-NEXT: {{^\-.b.a.z.$}}
 # CHECK-NEXT: +foo
 # CHECK-NEXT: +bar
@@ -576,7 +584,7 @@
 # CHECK: $ "cat" "diff-in.bin"
 # CHECK: # command output:
 # CHECK-NEXT: {{^.f.o.o.$}}
-# CHECK-NEXT: {{^.b.a.r..}}
+# CHECK-NEXT: {{^.b.a.r.}}
 # CHECK-NEXT: {{^.b.a.z.$}}
 # CHECK-NOT: error
 # CHECK: $ "false"