Add some noexcepts

This is to assert that callback functions should never throw (since
the context in which they're called may not be able to handle the
exception).

src/libstore/binary-cache-store.cc

@@ -55,7 +55,7 @@ void BinaryCacheStore::init()
 }
 
 void BinaryCacheStore::getFile(const std::string & path,
-    Callback<std::shared_ptr<std::string>> callback)
+    Callback<std::shared_ptr<std::string>> callback) noexcept
 {
     try {
         callback(getFile(path));
@@ -240,7 +240,7 @@ void BinaryCacheStore::narFromPath(const Path & storePath, Sink & sink)
 }
 
 void BinaryCacheStore::queryPathInfoUncached(const Path & storePath,
-    Callback<std::shared_ptr<ValidPathInfo>> callback)
+    Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept
 {
     auto uri = getUri();
     auto act = std::make_shared<Activity>(*logger, lvlTalkative, actQueryPathInfo,

src/libstore/binary-cache-store.hh

@@ -47,7 +47,7 @@ public:
     /* Fetch the specified file and call the specified callback with
        the result. A subclass may implement this asynchronously. */
     virtual void getFile(const std::string & path,
-        Callback<std::shared_ptr<std::string>> callback);
+        Callback<std::shared_ptr<std::string>> callback) noexcept;
 
     std::shared_ptr<std::string> getFile(const std::string & path);
 
@@ -73,7 +73,7 @@ public:
     bool isValidPathUncached(const Path & path) override;
 
     void queryPathInfoUncached(const Path & path,
-        Callback<std::shared_ptr<ValidPathInfo>> callback) override;
+        Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept override;
 
     Path queryPathFromHashPart(const string & hashPart) override
     { unsupported("queryPathFromHashPart"); }

src/libstore/http-binary-cache-store.cc

@@ -131,7 +131,7 @@ protected:
     }
 
     void getFile(const std::string & path,
-        Callback<std::shared_ptr<std::string>> callback) override
+        Callback<std::shared_ptr<std::string>> callback) noexcept override
     {
         checkEnabled();
 

src/libstore/legacy-ssh-store.cc

@@ -88,7 +88,7 @@ struct LegacySSHStore : public Store
     }
 
     void queryPathInfoUncached(const Path & path,
-        Callback<std::shared_ptr<ValidPathInfo>> callback) override
+        Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept override
     {
         try {
             auto conn(connections->get());

src/libstore/local-store.cc

@@ -629,7 +629,7 @@ uint64_t LocalStore::addValidPath(State & state,
 
 
 void LocalStore::queryPathInfoUncached(const Path & path,
-    Callback<std::shared_ptr<ValidPathInfo>> callback)
+    Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept
 {
     try {
         auto info = std::make_shared<ValidPathInfo>();

src/libstore/local-store.hh

@@ -127,7 +127,7 @@ public:
     PathSet queryAllValidPaths() override;
 
     void queryPathInfoUncached(const Path & path,
-        Callback<std::shared_ptr<ValidPathInfo>> callback) override;
+        Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept override;
 
     void queryReferrers(const Path & path, PathSet & referrers) override;
 

src/libstore/remote-store.cc

@@ -349,7 +349,7 @@ void RemoteStore::querySubstitutablePathInfos(const PathSet & paths,
 
 
 void RemoteStore::queryPathInfoUncached(const Path & path,
-    Callback<std::shared_ptr<ValidPathInfo>> callback)
+    Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept
 {
     try {
         std::shared_ptr<ValidPathInfo> info;

src/libstore/remote-store.hh

@@ -41,7 +41,7 @@ public:
     PathSet queryAllValidPaths() override;
 
     void queryPathInfoUncached(const Path & path,
-        Callback<std::shared_ptr<ValidPathInfo>> callback) override;
+        Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept override;
 
     void queryReferrers(const Path & path, PathSet & referrers) override;
 

src/libstore/store-api.cc

@@ -329,13 +329,14 @@ ref<const ValidPathInfo> Store::queryPathInfo(const Path & storePath)
 
 
 void Store::queryPathInfo(const Path & storePath,
-    Callback<ref<ValidPathInfo>> callback)
+    Callback<ref<ValidPathInfo>> callback) noexcept
 {
-    assertStorePath(storePath);
-
-    auto hashPart = storePathToHash(storePath);
+    std::string hashPart;
 
     try {
+        assertStorePath(storePath);
+
+        hashPart = storePathToHash(storePath);
 
         {
             auto res = state.lock()->pathInfoCache.get(hashPart);

src/libstore/store-api.hh

@@ -360,12 +360,12 @@ public:
 
     /* Asynchronous version of queryPathInfo(). */
     void queryPathInfo(const Path & path,
-        Callback<ref<ValidPathInfo>> callback);
+        Callback<ref<ValidPathInfo>> callback) noexcept;
 
 protected:
 
     virtual void queryPathInfoUncached(const Path & path,
-        Callback<std::shared_ptr<ValidPathInfo>> callback) = 0;
+        Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept = 0;
 
 public:
 

src/libutil/util.hh

@@ -460,7 +460,7 @@ public:
         if (prev) done.test_and_set();
     }
 
-    void operator()(T && t)
+    void operator()(T && t) noexcept
     {
         auto prev = done.test_and_set();
         assert(!prev);
@@ -469,7 +469,7 @@ public:
         fun(promise.get_future());
     }
 
-    void rethrow(const std::exception_ptr & exc = std::current_exception())
+    void rethrow(const std::exception_ptr & exc = std::current_exception()) noexcept
     {
         auto prev = done.test_and_set();
         assert(!prev);