From d5e10c18d323218991b20e61f4926117b83a3b68 Mon Sep 17 00:00:00 2001
From: Thomas Jarosch <thomas.jarosch@intra2net.com>
Date: Mon, 22 Dec 2014 11:15:22 +0100
Subject: [PATCH] checkUnreachableCode(): fix FP for statements that just hide
 compiler warnings about unused function arguments

Seen throughout the rockbox codebase.
---
 lib/checkother.cpp | 18 +++++++++++++++++-
 test/testother.cpp | 21 +++++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index dc97baa05..9295a0995 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -1189,7 +1189,23 @@ void CheckOther::checkUnreachableCode()
                             }
                         }
                     }
-                    if (!labelInFollowingLoop)
+
+                    // hide FP for statements that just hide compiler warnings about unused function arguments
+                    bool silencedCompilerWarningOnly = false;
+                    const Token *silencedWarning = secondBreak;
+                    for (;;) {
+                        if (Token::Match(silencedWarning, "( void ) %var% ;")) {
+                            silencedWarning = silencedWarning->tokAt(5);
+                            continue;
+                        } else if (silencedWarning && silencedWarning == scope->classEnd)
+                            silencedCompilerWarningOnly = true;
+
+                        break;
+                    }
+                    if (silencedWarning)
+                        secondBreak = silencedWarning;
+
+                    if (!labelInFollowingLoop && !silencedCompilerWarningOnly)
                         unreachableCodeError(secondBreak, inconclusive);
                     tok = Token::findmatch(secondBreak, "[}:]");
                 } else
diff --git a/test/testother.cpp b/test/testother.cpp
index e49c6da42..7c2605442 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -2965,6 +2965,27 @@ private:
               "}", 0, false, false, false, false);
         ASSERT_EQUALS("[test.cpp:3]: (style) Statements following return, break, continue, goto or throw will never be executed.\n", errout.str());
 
+        check("int foo(int unused) {\n"
+              "    return 0;\n"
+              "    (void)unused;\n"
+              "}", 0, false, false, false, false);
+        ASSERT_EQUALS("", errout.str());
+
+        check("int foo(int unused1, int unused2) {\n"
+              "    return 0;\n"
+              "    (void)unused1;\n"
+              "    (void)unused2;\n"
+              "}", 0, false, false, false, false);
+        ASSERT_EQUALS("", errout.str());
+
+        check("int foo(int unused1, int unused2) {\n"
+              "    return 0;\n"
+              "    (void)unused1;\n"
+              "    (void)unused2;\n"
+              "    foo();\n"
+              "}", 0, false, false, false, false);
+        ASSERT_EQUALS("[test.cpp:5]: (style) Statements following return, break, continue, goto or throw will never be executed.\n", errout.str());
+
         check("int foo() {\n"
               "    if(bar)\n"
               "        return 0;\n"