Instrument.adb: Disambiguate hash-based slugs for Ada units

Change the string from which the hash is computed when generating
a slug for an Ada unit to avoid collisions.

The hash was computed from the symbol string of the unit name, but
this transformation can result in the same symbol name being produced
for two units: Foo.Bar and Foo_Bar will both be turned into foo_bar.

Instead, use the human readable slug as a basis to compute the hash.

Author: leocreuse

testsuite/tests/147-slug_collision/src/pkg-child.adb

@@ -0,0 +1,8 @@
+package body Pkg.Child is
+
+   function Foo (X : Integer) return Integer is
+   begin
+      return X; -- # stmt
+   end Foo;
+
+end Pkg.Child;

testsuite/tests/147-slug_collision/src/pkg-child.ads

@@ -0,0 +1,3 @@
+package Pkg.Child is
+   function Foo (X : Integer) return Integer;
+end Pkg.Child;

testsuite/tests/147-slug_collision/src/pkg.ads

@@ -0,0 +1,2 @@
+package Pkg is
+end Pkg;

testsuite/tests/147-slug_collision/src/pkg_child.adb

@@ -0,0 +1,8 @@
+package body Pkg_Child is
+
+   function Bar (X : Integer) return Integer is
+   begin
+      return X; -- # stmt
+   end Bar;
+
+end Pkg_Child;

testsuite/tests/147-slug_collision/src/pkg_child.ads

@@ -0,0 +1,3 @@
+package Pkg_Child is
+   function Bar (X : Integer) return Integer;
+end Pkg_Child;

testsuite/tests/147-slug_collision/src/test_collision.adb

@@ -0,0 +1,13 @@
+with Support; use Support;
+
+with Pkg.Child;
+with Pkg_Child;
+
+procedure Test_Collision is
+begin
+   Assert (Pkg.Child.Foo (3) = Pkg_Child.Bar (3));
+end Test_Collision;
+
+--# pkg-child.adb pkg_child.adb
+--
+-- /stmt/ l+ ## 0

testsuite/tests/147-slug_collision/test.py

@@ -0,0 +1,14 @@
+"""
+Regression test: gnatcov used to generated homonym buffer units for a
+"Pkg.Child" unit and a "Pkg_Child" unit, as well as duplicate constant
+declarations in some generated units, which prevented the build of the
+instrumented sources.
+"""
+
+from SCOV.tc import TestCase
+from SCOV.tctl import CAT
+from SUITE.context import thistest
+
+
+TestCase(category=CAT.stmt).run()
+thistest.result()

tools/gnatcov/instrument.adb

@@ -154,18 +154,6 @@ package body Instrument is
       First  : Boolean := True;
       Result : Ada_Identifier;
    begin
-      if Use_Hash then
-
-         --  Prefix the hash with "z_" to ensure the unit name slug doesn't
-         --  start with a digit.
-
-         return
-           "z" & Strip_Zero_Padding
-                    (Hex_Image
-                       (Unsigned_32
-                          (Ada.Strings.Hash (To_Symbol_Name (Name)))));
-      end if;
-
       --  Create a unique slug from the qualified name: replace occurrences of
       --  'z' with 'zz' and insert '_z_' between identifiers.
 
@@ -187,7 +175,20 @@ package body Instrument is
             end;
          end loop;
       end loop;
-      return To_String (Result);
+
+      if Use_Hash then
+
+         --  Prefix the hash with "z" to ensure the unit name slug doesn't
+         --  start with a digit.
+
+         return
+           "z" & Strip_Zero_Padding
+                    (Hex_Image
+                       (Unsigned_32
+                          (Ada.Strings.Hash (To_String (Result)))));
+      else
+         return To_String (Result);
+      end if;
    end Qualified_Name_Slug;
 
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