From 68fa4011c80aa72ff905b025dbe2a4917d54935e Mon Sep 17 00:00:00 2001
From: Joel Rosdahl <joel@rosdahl.net>
Date: Thu, 30 Jul 2020 20:57:21 +0200
Subject: [PATCH] Remove last usage of legacy str_startswith macro

---
 src/Util.cpp           |  8 ++++++++
 src/Util.hpp           |  3 ++-
 src/ccache.cpp         | 14 ++++++++++----
 unittest/test_Util.cpp | 17 +++++++++++++++++
 4 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/src/Util.cpp b/src/Util.cpp
index 8678b1c62..0476bc224 100644
--- a/src/Util.cpp
+++ b/src/Util.cpp
@@ -1137,6 +1137,14 @@ split_into_strings(string_view input, const char* separators)
   return split_at<std::string>(input, separators);
 }
 
+bool
+starts_with(const char* string, nonstd::string_view prefix)
+{
+  // Optimized version of starts_with(string_view, string_view): avoid computing
+  // the length of the string argument.
+  return strncmp(string, prefix.data(), prefix.length()) == 0;
+}
+
 bool
 starts_with(string_view string, string_view prefix)
 {
diff --git a/src/Util.hpp b/src/Util.hpp
index 0141f3fae..149d709ff 100644
--- a/src/Util.hpp
+++ b/src/Util.hpp
@@ -356,7 +356,8 @@ std::vector<nonstd::string_view> split_into_views(nonstd::string_view input,
 std::vector<std::string> split_into_strings(nonstd::string_view input,
                                             const char* separators);
 
-// Return true if prefix is a prefix of string.
+// Return true if `prefix` is a prefix of `string`.
+bool starts_with(const char* string, nonstd::string_view prefix);
 bool starts_with(nonstd::string_view string, nonstd::string_view prefix);
 
 // Returns a copy of string with the specified ANSI CSI sequences removed.
diff --git a/src/ccache.cpp b/src/ccache.cpp
index 2ecc1f10a..3e8a2341f 100644
--- a/src/ccache.cpp
+++ b/src/ccache.cpp
@@ -425,6 +425,13 @@ process_preprocessed_file(Context& ctx,
   // There must be at least 7 characters (# 1 "x") left to potentially find an
   // include file path.
   while (q < end - 7) {
+    static const string_view pragma_gcc_pch_preprocess =
+      "pragma GCC pch_preprocess ";
+    static const string_view hash_31_command_line_newline =
+      "# 31 \"<command-line>\"\n";
+    static const string_view hash_32_command_line_2_newline =
+      "# 32 \"<command-line>\" 2\n";
+
     // Check if we look at a line containing the file name of an included file.
     // At least the following formats exist (where N is a positive integer):
     //
@@ -449,15 +456,14 @@ process_preprocessed_file(Context& ctx,
         // GCC:
         && ((q[1] == ' ' && q[2] >= '0' && q[2] <= '9')
             // GCC precompiled header:
-            || (q[1] == 'p'
-                && str_startswith(&q[2], "ragma GCC pch_preprocess "))
+            || Util::starts_with(&q[1], pragma_gcc_pch_preprocess)
             // HP/AIX:
             || (q[1] == 'l' && q[2] == 'i' && q[3] == 'n' && q[4] == 'e'
                 && q[5] == ' '))
         && (q == data.data() || q[-1] == '\n')) {
       // Workarounds for preprocessor linemarker bugs in GCC version 6.
       if (q[2] == '3') {
-        if (str_startswith(q, "# 31 \"<command-line>\"\n")) {
+        if (Util::starts_with(q, hash_31_command_line_newline)) {
           // Bogus extra line with #31, after the regular #1: Ignore the whole
           // line, and continue parsing.
           hash.hash(p, q - p);
@@ -467,7 +473,7 @@ process_preprocessed_file(Context& ctx,
           q++;
           p = q;
           continue;
-        } else if (str_startswith(q, "# 32 \"<command-line>\" 2\n")) {
+        } else if (Util::starts_with(q, hash_32_command_line_2_newline)) {
           // Bogus wrong line with #32, instead of regular #1: Replace the line
           // number with the usual one.
           hash.hash(p, q - p);
diff --git a/unittest/test_Util.cpp b/unittest/test_Util.cpp
index fb76f43b7..34f2c5d9d 100644
--- a/unittest/test_Util.cpp
+++ b/unittest/test_Util.cpp
@@ -764,6 +764,7 @@ TEST_CASE("Util::split_into_strings")
 
 TEST_CASE("Util::starts_with")
 {
+  // starts_with(const char*, string_view)
   CHECK(Util::starts_with("", ""));
   CHECK(Util::starts_with("x", ""));
   CHECK(Util::starts_with("x", "x"));
@@ -778,6 +779,22 @@ TEST_CASE("Util::starts_with")
   CHECK_FALSE(Util::starts_with("", "x"));
   CHECK_FALSE(Util::starts_with("x", "y"));
   CHECK_FALSE(Util::starts_with("x", "xy"));
+
+  // starts_with(string_view, string_view)
+  CHECK(Util::starts_with(std::string(""), ""));
+  CHECK(Util::starts_with(std::string("x"), ""));
+  CHECK(Util::starts_with(std::string("x"), "x"));
+  CHECK(Util::starts_with(std::string("xy"), ""));
+  CHECK(Util::starts_with(std::string("xy"), "x"));
+  CHECK(Util::starts_with(std::string("xy"), "xy"));
+  CHECK(Util::starts_with(std::string("xyz"), ""));
+  CHECK(Util::starts_with(std::string("xyz"), "x"));
+  CHECK(Util::starts_with(std::string("xyz"), "xy"));
+  CHECK(Util::starts_with(std::string("xyz"), "xyz"));
+
+  CHECK_FALSE(Util::starts_with(std::string(""), "x"));
+  CHECK_FALSE(Util::starts_with(std::string("x"), "y"));
+  CHECK_FALSE(Util::starts_with(std::string("x"), "xy"));
 }
 
 TEST_CASE("Util::strip_whitespace")
-- 
2.47.3