Fix some possible performance issues found by clang-tidy

No obvious time differences when building AOSP, but these all seem like
reasonable changes.

6 files changed, 10 insertions, 5 deletions

diff --git a/Android.bp b/Android.bp
index f95b366..8dbb9cb 100644
--- a/Android.bp
+++ b/Android.bp
@@ -25,6 +25,11 @@ cc_defaults {
             host_ldlibs: ["-lrt", "-lpthread"],
         },
     },
+    tidy_checks: [
+        "-google-global-names-in-headers",
+        "-google-build-using-namespace",
+        "-google-explicit-constructor",
+    ],
 }
 
 cc_library_host_static {
diff --git a/dep.cc b/dep.cc
index 502ec47..4bdf9ab 100644
--- a/dep.cc
+++ b/dep.cc
@@ -534,7 +534,7 @@ class DepBuilder {
     if (found == suffix_rules_.end())
       return rule_merger;
 
-    for (shared_ptr<Rule> irule : found->second) {
+    for (const shared_ptr<Rule> &irule : found->second) {
       CHECK(irule->inputs.size() == 1);
       Symbol input = ReplaceSuffix(output, irule->inputs[0]);
       if (!Exists(input))
diff --git a/rule.cc b/rule.cc
index 68ec7f5..6942fb5 100644
--- a/rule.cc
+++ b/rule.cc
@@ -54,7 +54,7 @@ Rule::Rule()
 }
 
 void ParseRule(Loc& loc, StringPiece line, char term,
-               function<string()> after_term_fn,
+               const function<string()> &after_term_fn,
                Rule** out_rule, RuleVarAssignment* rule_var) {
   size_t index = line.find(':');
   if (index == string::npos) {
diff --git a/rule.h b/rule.h
index 4d72bb7..84412c1 100644
--- a/rule.h
+++ b/rule.h
@@ -65,7 +65,7 @@ struct RuleVarAssignment {
 // |term| is '='), |after_term_fn| will be called to obtain the right
 // hand side.
 void ParseRule(Loc& loc, StringPiece line, char term,
-               function<string()> after_term_fn,
+               const function<string()> &after_term_fn,
                Rule** rule, RuleVarAssignment* rule_var);
 
 #endif  // RULE_H_
diff --git a/strutil.cc b/strutil.cc
index 1b99dff..b094198 100644
--- a/strutil.cc
+++ b/strutil.cc
@@ -500,7 +500,7 @@ string ConcatDir(StringPiece b, StringPiece n) {
   return r;
 }
 
-string EchoEscape(const string str) {
+string EchoEscape(const string &str) {
   const char *in = str.c_str();
   string buf;
   for (; *in; in++) {
diff --git a/strutil.h b/strutil.h
index 12e46a5..d61160d 100644
--- a/strutil.h
+++ b/strutil.h
@@ -140,7 +140,7 @@ string SortWordsInString(StringPiece s);
 
 string ConcatDir(StringPiece b, StringPiece n);
 
-string EchoEscape(const string str);
+string EchoEscape(const string &str);
 
 void EscapeShell(string* s);