# Unreachable code in builtin-merge.c ? 4 messages from 2009-10-23 to 2009-10-23. Participants: Zivkov, Sasa, Mikael Magnusson, Joshua Roys. Thread: https://gitlist.dev/t/21337 ## Zivkov, Sasa, 2009-10-23 15:03 Subject: Unreachable code in builtin-merge.c ? Message-ID: URL: https://gitlist.dev/e/B221C4384AE5104EB414A877DFD0372C0B0092C0C5%40DEWDFECCR04.wdf.sap.corp ``` In the try_merge_strategy function the expression in the following if statement seems to always evaluate to TRUE: if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) { If strategy is "recursive" then !strcmp(strategy, "subtree") evaluates to TRUE. If strategy is "subtree" then !strcmp(strategy, "recursive") evaluates to TRUE. If strategy is neither "recursive" nor "subtree" then any side of || evaluates to TRUE. Looks like the code in the else block is unreachable? Saša Živkov ``` ## Mikael Magnusson, 2009-10-23 15:12 Subject: Re: Unreachable code in builtin-merge.c ? Message-ID: <237967ef0910230812r621ac705qb029dade20c455a7@mail.gmail.com> URL: https://gitlist.dev/e/237967ef0910230812r621ac705qb029dade20c455a7%40mail.gmail.com In-Reply-To: ``` 2009/10/23 Zivkov, Sasa : > In the try_merge_strategy function the expression in the following if statement seems to always evaluate to TRUE: > > if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) { > > If strategy is "recursive" then !strcmp(strategy, "subtree") evaluates to TRUE. > If strategy is "subtree" then !strcmp(strategy, "recursive") evaluates to TRUE. > If strategy is neither "recursive" nor "subtree" then any side of || evaluates to TRUE. > > Looks like the code in the else block is unreachable? You seem to have forgotten that strcmp returns 0 when the strings match. (It returns -1 or 1 when they don't, depending on their alphabetical ordering). -- Mikael Magnusson ``` ## Joshua Roys, 2009-10-23 15:14 Subject: Re: Unreachable code in builtin-merge.c ? Message-ID: <4AE1C863.3070907@gmail.com> URL: https://gitlist.dev/e/4AE1C863.3070907%40gmail.com In-Reply-To: ``` On 10/23/2009 11:03 AM, Zivkov, Sasa wrote: > In the try_merge_strategy function the expression in the following if statement seems to always evaluate to TRUE: > > if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) { > > If strategy is "recursive" then !strcmp(strategy, "subtree") evaluates to TRUE. > If strategy is "subtree" then !strcmp(strategy, "recursive") evaluates to TRUE. > If strategy is neither "recursive" nor "subtree" then any side of || evaluates to TRUE. > > Looks like the code in the else block is unreachable? > > > Saša Živkov > -- > To unsubscribe from this list: send the line "unsubscribe git" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Hello, Not quite :) The strcmp() function actually returns 0 when the strings match (I know, it looks weird "!strcmp" -> "not string compare?!"), so the "if" really means: "if strategy is equal to 'recursive' or 'subtree', do the following..." Hope to help, Josh ``` ## Zivkov, Sasa, 2009-10-23 15:39 Subject: RE: Unreachable code in builtin-merge.c ? Message-ID: URL: https://gitlist.dev/e/B221C4384AE5104EB414A877DFD0372C0B0092C117%40DEWDFECCR04.wdf.sap.corp In-Reply-To: <4AE1C863.3070907@gmail.com> ``` > Not quite :) The strcmp() function actually returns 0 when the strings > match (I know, it looks weird "!strcmp" -> "not string compare?!"), so Right! Now I remember it :-) This is what happens when one looks at C code after some 10+ years of !C development ;-) Saša Živkov ```